最新刊期
卷 ， 期 6 ， 2008
- 摘要：Recent studies of our group on polymer electrolytes for improving the long-term stability of dye-sentitized solar cells (DSSC) are summarized.We designed and synthesized a series of novel network gel polymer electrolytes having soft polyorganosiloxane main chains with grafted polyether as inner plastisizer or at the same time with quaternized ammonium side groups.We also synthesized PEO-based gel polymer electrolytes and PAN-based gel polymer electrolytes containing polyorgano siloxane quaternized iodine salt.These electrolytes were successfully employed in dye-sensitized solar cells.The ionic conductivity,electrochemical stability and mechanical processibility of these electrolytes meet the requirement of practical applications.Through optimization of the electrolyte components the photoelectrical conversion efficiency can be improved further.A novel system of in situ solidifiable polymer electrolytes was developed.The quaterization reaction of liquid latent chemical crosslinked precursors was used to prepare polymer electrolytes.This method can realize the in situ solidification of polymer electrolytes and facilitate the industrialization in a large scale.Chemical crosslinked precursors with low viscosity can easily penetrate into the electrode,which can reduce the contact resistance dramatically between electrolyte and electrode and favor the improvement of photoelectrical properties of solid state DSSC.Several types of dendritic oligo-polymers and co-polymers containing pyridine groups and copolymers containing imidazole groups as latent chemical crosslinked precursors were designed and synthesized,and they reacted with multi-halogen compounds to prepare all solid state polymer electrolytes.Also,the gel polymer electrolytes and quasi solid state polymer electrolytes were prepared in cooperation with liquid electrolytes and ionic liquid electrolytes.The photoelectrical conversion efficiency of dyesensitized solar cells constructed by gel polymer electrolytes and quasi solid state polymer electrolytes basically maintain the level of corresponding solar cells constructed by liquid electrolyte and ionic liquid electrolyte.The optimum values are close to 8% and 4.5%,respectively.The poly(ether methacrylate) grafting ionic liquid groups at the end of the polymer chain was designed and synthesized.DSSC using quasi solid state eletrolyte with such polymer and multicomposed ionic liquid electrolyte can reach the photoelectrical conversion efficiency of 6.10% and possess good thermal stability.
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发布时间：2021-03-19
Feature Articles
- 摘要：Two coating matrix materials, polyurethane and silicone rubber were used for investigating the relationship between absorption and molecular structure of polymers under hydraulic pressure. The polyurethane was synthesized with toluene diisocyanate and polyethylene glycol as main raw materials, and the silicone rubber was prepared with vinyl polydimethyl siloxane and hydrogen-containingsilicone fluid. The molecular structure of polymers was analyzed by using Fourier transform infrared spectroscopy. The sound absorption performance was measured by the standing wave tube method. The mechanical performance of coating films was characterized by tensile and shear moduli measurements, and their volume change under hydraulic pressure was simulated by using a file ANSYS 8.0. The different polymer presented different sound absorption performance under ordinary and hydraulic pressure. As frequency ranged from 3 to 30 kHz under ordinary pressure, the average absorption coefficient of silicone rubber-based coatings was 92.6%, and that of polyurethane-based coatings was 68.5%. The sound absorption performance of coatings changed noticeably with hydraulic pressure increased. The sound absorption performance of silicone rubber with flexible molecule chain structure decreased rapidly when the hydraulic pressure increased. The average absorption coefficient changed from 26.9% under 0.5 MPa down to 13% under 3 MPa. The sound absorption ability of polyurethane with rigid molecule chain structure increased when the hydraulic pressure increased. The average absorption coefficient changed from 75.2% under 0.5 MPa to 87.6% under 3 MPa. The results of finite element analysis showed that the volume compressibility of silicone rubber-based coatings increased from 0.55% to 3.29%, and that of polyurethane-based coatings changed from 0.03% to 0.20% when the hydraulic pressure increased from 0.5 MPa to 3 MPa. The polymer of polyurethane-based coatings was a polyether-type polyurethane with a large number of intermolecular hydrogen bonds and carbonate polar groups from TDI and hydroxyl groups. The cohesive power of the carbonate groups was very large, the total power of interaction of the rigid molecule chains with large numbers of carbonate groups was powerful, which engendered network-like structure among linear chains. The free volume of polyurethane with rigid molecule chains changed slightly as the volume compressibility was less under hydraulic pressure. The flexible molecule chains of silicone rubber were easy to slide under hydraulic pressure, which resulted in rapid decrease of free volume, and the molecular motion was blocked. The sound absorption performance was affected by the size free volume and the movement of polymer molecules. These results indicate the importance of molecular structure and free volume adjusting in preparing excellent anechoic coatings under high hydraulic pressure.
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发布时间：2021-03-19 - 摘要：Poly(vinyldiene fluoride) (PVDF) asymmetrical membranes using three solvents N,N-dimethylforamide(DMF),N,N-dimethylacetamide(DMAc), and dimethylsulfoxide(DMSO) were prepared by phase inversion process.The thermodynamic properties of the casting solutions and the kinetic diffusion during membrane-forming processes were investigated via cloud point determination and light transmittance measurements. It was found that the thermodynamic stability of the casting solutions was enhanced gradually from DMSO/PVDF/water,DMF/PVDF/water to DMAc/PVDF/water, the delayed demixing due to the decrease of kinetic diffusion rates was easier to occur as the solvents were changed from DMF,DMAc to DMSO. The characterization of membranes showed that membranes containing a macrovoid structure were fabricated with higher porosity and lower crystallinity when DMSO and DMAc were used as solvent,but the honeycomb-structure membranes with higher crystallinity and lower porosity were prepared from DMF solvent, which indicated that the three membranes morphologies and properties were not controlled by the thermodynamic property or kinetic process uniformly. As a result,based on the theory of “the predominance on the growth of preformed nucleus" and the macrovoid development, the influences of the three solvents on the phase separation behavior of PVDF casting solutions,PVDF aggregate structure and membrane structure were discussed by the membrane formation mechanism of skin-sublayer two step precipitation. The results showed that for the three membrane-forming systems using DMF,DMAc and DMSO as solvent respectively, the delayed solid-liquid demixing took place in the skin layer under the control of the thermodynamics of casting solutions, and the dense skin layer formed with spherical particles.The delayed time was controlled by the kinetic diffusion. Mutual diffusion coefficient of solvent and non-solvent（Dm） increased gradually in the order of DMSO,DMAc,DMF,therefore,the delayed time decreased following the sequence of DMSO,DMAc, DMF. The phase transformation behaviors of the sublayers of the three membrane-forming systems were dominated by the liquid-liquid demixing controlled by the kinetic diffusion processes. For the systems with DMSO as solvent, the instantaneous liquid-liquid demixing happened in the sublayer, and crystallization had little effect on the kinetic diffusion. It was found in the light transmission that the demixing time was short, and curve variation was steep. Correspondingly, the membrane formed with a fingerlike macrovoid structure and a small amount of crystal spherulite in the sublayer,thus the membrane displayed the lower crystallinity and the higher membrane thickness,higher porosities and higher gas fluxes.For the systems with DMAc as solvent,the instantaneous liquid-liquid demixing happened in the sublayer. Compared to the DMSO system,crystallization had a great influence on the kinetic diffusion, leading to the longer demixing time and the flat curve variation in the light transmission drawing.Accordingly,the membrane was fabricated with an amount of crystal spherulite and the concurrent structure of macrovoid and spongy-like pores in the sublayer, and the membrane displayed the high crystallinity and the low membrane thickness, porosities and gas fluxes.For the system with DMF as solvent, compared to the DMSO and DMAc systems,the delayed liquid-liquid demixing initiated in the sublayer, and the crystallization had a greatest effect on the kinetic precipitation process, resulting in the longer demixing time and the flatter curve variation in the light transmission drawing.Finally, the membrane with a honeycomb-structure sublayer was prepared with the higher crystallinity and the smaller thickness,porosities and gas fluxes.
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发布时间：2021-03-19 - 摘要：A physical gel is a three-dimensional network of polymer chains cross-linked by physical junctions, and it can arise either as the result of a phase transition or through some specific molecular association or as a result of entanglements. Due to the complexity of the inner structure and gelation mechanism, it is difficult to obtain purposefully polymer physical gel materials with specific constitution and properties. Thus, the controllable preparation and application of polymer physical gels are a long-term work.As a numerical simulation method in macro-scale the finite element method has been used to the study of chemical gelation,but rarely to physical gelation presently. The reasons may be: compared with chemical gels the gelation process of physical gels is more complex resulting from the bigger complexity of the system composition and physical interactions. Several kinds of interactions and steps may be involved in one physical gelation process. And under different conditions the gelation mechanisms are frequently different. By now the understanding of the gelation mechanisms of many kinds of physical gels is far from being intensive; the phenomenological gelation kinetics models are usually nonlinear; the theory describing the relation between the microscopic and mesoscopic structure and the macroscopic properties is still immature. For all the factors mentioned above the numerical simulation of physical gelation process in macro-scale comes to be a difficult work. In order to optimize raw material formulation and physical gelation conditions, and then obtain polymer physical gels according to requirements, the spatial distribution and time evolution characteristics of the temperature field during the gelation process were studied via the finite element method. On the basis of the temperature field calculated, the complex shear modulus field of gel system was numerically simulated according to a first-order gelation kinetic equation, and the effects of raw material concentration, sample size and cooling modes on the physical gelation were discussed.Rennet casein gel is a kind of particle gel,whose formation is controlled by physical forces including steric-hydration force and van der Waals force,and whose structure and properties are influenced by many parameters including emulsifying salts,pH,thermal and shear history.The formation process of the gel network can be divided into three steps, molecules-particles-flocs-network. Casein flocs are fractal objects that can be partially filled by the constructing units (particles).The fractal dimension of the flocs and the size of the particles are two important parameters determining the gel microscopic structure and rheological properties. Experimental results show that cooling modes will influence the rheological properties of the gel through influencing the size of the particles. The formation of rennet casein gels is a first-order kinetics process.Three examples were studied. The raw material concentrations of example 1 and example 2 are both 18%,but the sample size of the former is five times as that of the latter; the raw material concentration of example 3 is 25%,and the sample size is same with example 1. The gel zone is divided into 136 unites and 163 nodes; the prototype zone is divided into 28 unites and 40 nodes; four representative nodes were selected in the gel zone, and were emphatically studied. The initial system temperature is set at 80℃,and cooling modes include (1) environmental temperature declines from 80℃ to 5℃,and cooling rates are respectively 0.5 K/min,0.25 K/min,0.1 K/min,0.05 K/min,0.025 K/min; (2) environmental temperature maintains 5℃.The simulated results show that (1) the rate of temperature decrease near the surface is larger than that near the center, the gelation occurs on the surface first; as the infinite complex shear modulus is determined by the cooling rate of the pre-gelation phase, the value of the complex shear modulus of the interior exceeds that of the exterior finally. The asymmetric distribution of temperature field results in the asymmetric distribution of mechanical property field of the gel. And with the increase of environmental cooling rate and sample size the asymmetry becomes more obvious.
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发布时间：2021-03-19 - 摘要：Four kinds of sterically hindered groups-based hyperbranched polyfluorene copolymers containing different branching units such as benzene or triphenylamine were designed and synthesized. All the monomers such as 2,7-dibromo-9,9-dioctylfluorene,2,7-dibromospiro(fluorine-9,9′-xanthene), 9,9-dioctylfluorene-2,7-bis(4,4,5,5-tetramethyl-1,3,2-dioxaborolane) and 9,9-dioctylfluorene-2-boronic acid were prepared according to the literature procedures.Suzuki polycondensation (SPC) with the branching units and linear units was conducted in biphasic system (toluene/aqueous Na2CO3) with Pd(PPh3)4 as a catalyst precursor. The reaction mixture containing monomers was kept stirring at 72℃ under nitrogen for 60 h at the polymerization stage. Then,the end-capped group was added to the reaction mixture together with additional Pd(PPh3) 4 in order to reduce the heavy atom effect which quenched fluorescence. The reaction was continued for further 12 h. After cooling to room temperature, some amount of thiourea was added, and then the mixture was vigorously stirred for another 3 h. The mixture was filtrated to remove the catalyst residues and extracted with toluene. After removal most of the solvent,the crude polymer in certain amount of toluene was added dropwise to methanol and the formed precipitate was recovered by filtration. The solid was washed with methanol, water and again with methanol, then followed by Soxhlet extraction with acetone for 48 h to remove oligomer. The yellow powder was collected and dried under vacuum. All the resulting hyperbranched copolymers are soluble in common organic solvents, such as tetrahydrofuran, chloroform and toluene. The structures of the hyperbranched polymers were fully characterized by NMR, GPC, elementary analysis and thermogravimetric analysis. The degrees of branching of the polymers were calculated through the integration of the characteristic signals of the branching units and linear units from the high-resolution NMR spectroscopy. The GPC experimental results showed that the number-average molecular weights of the polymers were from 11200 to 17200The thermal degradation temperatures (weight loss 5%) of the polymers were nearly at 400℃.Cyclic voltammetry (CV) was used to assess the electrochemical behavior of the polymers. The polymers show a reversible oxidation/reduction wave which can be assigned to the oxidation/reduction potential of copolymer main chain from the onset. The HOMO level of the polymer containing triphenylamine is lower than that containing benzene, which indicated less difficulty in hole injection.The photophysical characteristics of the polymers were investigated in solution and in solid films.Solid films on quartz plates used for UV-Vis, fluorescence were prepared by spin-coating with 10-3 mol/L tetrahydrofuran solution. The absorption maxima of the polymers are blue-shifted within 10 nm compared to that in solution. In addition, the PL maxima remain unchanged or are only slightly red-shifted. Their thermal stability was investigated from the change of fluorescent spectra in solid films after annealing at elevated temperature in air. There was no obvious change in the PL spectra, and no additional green-blue band emission was observed even after the film was annealed at 200℃ in air. Apparently, with the introduction of spirofluorene/large aromatic units to the hyperbranched structure, the red-shifted phenomena and the undesirable low-energy long wavelength emission band are reduced remarkably. All results indicated that the tendency to form aggregate/excimers in the solid state was efficiently suppressed, and the spectral stability of the polymers was greatly improved.
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发布时间：2021-03-19 - 摘要：The goal of present investigation is to produce high biomass content biopolyol, which has the potential of replacing the expensive polyether polyol in manufacturing of polyurethane foams, through a thermochemical liquefaction process by using bamboo residues combined with corn starch as raw material. Single factor experimental design was adopted to test the effect of the composition of liquefaction reagent, the different liquid ratio and the proportion of bamboo to starch on the physical and chemical properties of the resulting liquefaction products. Polyurethane foam was prepared by using this liquefaction products instead of polyether polyol. Finally,the physical mechanical properties and biodegradability of the resulting polyurethane foam were determined according to the simplified ASTM D5338.98 test method. The experimental results showed that the best resulting biopolyol was obtained by using 50 wt% of ethylene carbonate+50 wt% of ethylene glycol as complex liquefaction solvent, adding 3 wt% of fuming sulfuric acid to liquefaction solvent as catalyst, under the reaction temperature of (150±5)℃ (oil bath) and atmosphere pressure, and the reaction time lasted for 150 min with constant agitation within present experimental design. Only less than 30% of the bamboo residues can be well dissolved in the complex solvent due to the tendency of secondary condensation of the liquefied components.In order to reduce the production cost of the biopolyol by increasing its biomass content,15 wt%～25 wt% of bamboo residue combined with 125 wt%～135 wt% of corn starch over the liquefaction solvent was liquefied stepwise. The viscosity of the liquefaction mixture resulting from the combined liquefaction of 25 wt% bamboo residue and 125 wt% corn starch is as high as 8.85 Pa．s,which is not suitable for polyurethane foam preparation, and the polymer segment content in the liquefaction product of the pure bamboo residues was so low that the resulting polyurethane foam collapsed badly. When combined liquefaction mixture of 20 wt% of bamboo residue and 130 wt% of corn starch was blend with 4,4′-diphenylmethane diisocyanate (MDI) and the other additives with the molar ratio of (—NCO/—OH) equal to 1.1,polyurethane foams with acceptable mechanical properties: apparent density of 33.6 kg/m3,compressive strength of 118 kPa and elastic modulus of 6.91 MPa were obtained. The biodegradability determined was 12.63%, expressed by weight loss in one year round.
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发布时间：2021-03-19 - 摘要：Glass transition temperature (Tg) is an important intrinsic parameter of polymers,which greatly affects their properties and application. Tg of a polymer could be changed through copolymerization.It is well known that Tg of a copolymer usually deviates from the additivity of that of the homopolymers.Tg of a copolymer was affected not only by the composition but also by the sequence distribution of the copolymer.Many researchers have proposed various equations to describe the copolymer Tg composition relationship based on free volume theory as well as thermodynamic theory of glass transition.Among them,Johnston and Barton considered the diad effect,and better fitting result between the theory predicted and experimental data was obtained.Whereas they failed when the Tg composition curve is asymmetric or even S-shaped.When triad sequence effect was taken into consideration,the fitting was greatly improved.Unfortunately,there are 6 intractable parameters in the equation which greatly holdback its application.Ham and Uematsu proposed their methods to reduce the number of intractable parameters to 1,which increased the facility of the triad sequence equation.Whereas the manners they proposed were unreasonable.It is found that all the equations proposed by now were based on the additivity of contributions of different monomers or sequences.In this paper,we propose an equation based on the additivity of contributions of different bonds concerning the substitution on the adjacent C atoms.For the case of a headtotail binary copolymer composed of mono-substituted vinyl monomers,the bonds were classified into 8 kinds when the substitutions on C1,C2 and C3 were concerned.Based on the thermodynamic theory of glass transition,the equation is described as below under the assumption of steady-state concentration. Tg=nAAATgA+nBBBTgB+2(nABA-nAAB)Tg［AB］+3nAABTg［AAB］+3nBBATg［BBA］Where nijk represents the mole fraction of triad sequence ijk, Tg［x］is Tg of periodic copolymer poly［x］.nijk could be obtained experimentally or calculated from the monomer feed compositions and reactivity ratios.The equation could be applied to investigate the relation between copolymer Tgs and compositions conveniently because that it contains no mere fitting parameter.If the periodic copolymers poly［AAB］ and poly［BBA］ cannot be acquired,there are only two intractable parameters in the equation.Even if the alternating copolymer poly［AB］ also cannot be acquired,there are only three adjustable parameters,far less than the original six in the Ham equation.More over, Tgs of them could be predicted by using the equation and Tg data of random copolymers for this case.The new equation was applied to MMA-St and E-VAc random copolymers,and excellent fitting was obtained.Whereas large deviations pronounced when only diad sequence effect was taken into consideration.Especially for the case of E-VAc copolymers,the predicted Tgs show opposite derivation compared with the experimental results.Tgs of corresponding periodic copolymers were also evaluated.This equation may be extended to describe multi-copolymers or block,graft copolymers only if no phase separation appears in their bulk.Also the fact of Tg changed with tacticity,such as PMMA,may be explained by using this equation.
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发布时间：2021-03-19 - 摘要：The influence of copolymer composition on the viscoelastic relaxation and the morphology of styrene-butadiene- styrene triblock copolymers (SBS) were investigated by using dynamic rheological measurements and transmission electron microscope (TEM).Through the TEM observation,it is found that the three kinds of SBS with various styrene contents present lamellar structures and the domain size of styrene (PS) phase decreases slightly,however the size of butadiene (PB) phase increases with the decrease of styrene contents.It has been accepted that the period of microdomains of block copolymer is at the same order with the size of the polymer chain coil in molten state,i.e.Rg∝N1/2.The N1/2 of PS block and PB block in each SBS were calculated cursorily,which was coincided with the TEM observation.But the exact size of each phase could not be confirmed only by means of the TEM micrographs.Three relaxation peaks in the plot of loss factor (tanδ) and temperature (T) at different frequencies(ω) were observed,which should owe to the relaxation of various motorial unit of SBS.The glass transition temperature(Tg or T2) of PS phase and the orderdisorder transition (ODT) temperature (T3) for various SBS were obtained from the plot of tanδ T.The results exhibit that T2 reduces slightly with the styrene contents decrease.The decrease of T2 is mainly caused by the reducing of the molecular weight of styrene blocks of SBS.Comparing with T2, T3 descends rather remarkably,which is considered to be concerned with PB block.In addition,it revealed that the ODT peak could not be observed if ω was too high during dynamic measurements.Only when ω was lower than 0.1 rad/s,a notable ODT peak could be gained. Two plateaus in the G ′(or G″) -T-ω three dimension graph and two humps in the tanδ - ω -three dimension graph were observed.The hump “b” at high temperatures and low ω region is considered to be related to the ODT behavior.An interesting thing is that SBS with low styrene contents shows a huge hump “b"compared with the SBS with high styrene contents in spite of almost identical polymer molecular weight.High quantity of tanδ in dynamic measurements means drastic internal friction and will lead to large energy dissipation.Usually,tanδ isinversely proportional to the diffusion coefficient (D) of a reptating chain. D is inversely proportional to N2.Therefore, N2 of PS block,PB block and the whole SBS chain were calculated roughly.Due to the small molecular weight of butadiene monomer,the SBS with low styrene content actually possesses longer chain length and exhibits larger N2 compared with the SBS with high styrene content.Consequently,long chain gives rise to large inner friction during ODT and huge tanδ peak on account of the viscoelastic nature of polymer.In summary,although the temperature of ODT is mainly decided by the styrene contents,however,the energy dissipation during the ODT transition mostly comes from the inner friction of PB block as well as the whole SBS chain.
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发布时间：2021-03-19 - 摘要：A cationic polyacrylamide was synthesized by polymerization of acrylamide and 2- (methacryloyloxy)-ethyltrimethylammonium chloride (AM/MADQUAT)in solution or by inverse microemulsion polymerization using (NH4) 2S2O8/NaHSO3 as redox initiator.The sequence distribution and composition distribution were calculated from monomer reactivity ratios of different polymerization methods.The resuls show that charge distribution is more uniform for the copolymer prepared in inverse microemulsion,and copolymer composition distribution is close to unity and maintains approximately at feed ratio.Furthermore,influence of the structure of cationic polyacrylamides on kaolinite flocs size,reduction of zeta potential and flocs compressive yield stress has been investigated at pH 7.The results show that the kaolinite flocs size is strongly dependent upon copolymer microstructure; with greater flocs size being observed for copolymer prepared in inverse microemulsion than for that in solution.Copolymer microstructure has a marked effect on the zeta potential,whose decrease in magnitude was much greater in the presence of copolymer prepared in inverse microemulsion than that in solution.Greater compressive yield stress was achieved for the strong flocs produced by copolymer prepared in inverse microemulsion.The difference in flocs compressive yield stress may be attributed to the flocs structure.Therefore,in this paper,a strong correlation between the cationic polyacrylamide structure and flocculation property for kaolinite suspension was established.
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发布时间：2021-03-19 - 摘要：Metallophthalocyanine has attracted considerable attention as oxidation catalyst because its structure similar to the active center of cytochrome P-450,and it can promote many reactions through oxidase-like, catalase-like, as well as peroxidase-like mechanism, whereas it has the following problems:low solubility, high aggregation tendency,difficulty in catalyst recovery and recycling,which restrict its further application as catalyst.Poly(N-isopropylacrylamide) (PNIPAAm) is a typical thermosensitive polymer, and it can be homogeneous below its lower critical solution temperature (LCST) and completely precipitated above LCST, which makes it become an attractive polymer support for catalyst. A novel reactive and aqueous soluble metallophthalocyanine derivative, cobalt tetra(2,4-dichloro-1,3,5-triazine)aminophthalocyanine (Co-TDTAPc),was synthesized by the modification of cobalt aminophthalocyanine with 2,4,6-trichloro-1,3,5-triazine and immobilized on PNIPAAm by covalent bond to obtain a thermosensitive polymer catalyst, PNIPAAm-g-Co-TDTAPc. The polymer catalyst was characterized by UV-Vis spectrometer in ethanol and THF, and the results showed that PNIPAAm-g-Co-TDTAPc had characteristic absorption peaks of cobalt phthalocyanine (B band: 280～330 nm; Q band: 620～700 nm) in both ethanol and THF, while PNIPAAm had no absorption in these area, which proved that the Co-TDTAPc had been successfully grafted on PNIPAAm.The thermal stability of the polymers were also tested by heating from room temperature to 600℃ at a rate of 20 K/min in a nitrogen environment with flow rate of 100 mL/min.The results indicated that the beginning decomposition temperature of PNIPAAm-g-Co-TDTAPc was 407℃,which confirmed that the polymer catalyst had high thermal stability.The solubility of small molecular cobalt phthalocyanine, PNIPAAm and PNIPAAm-g-Co-TDTAPc was investigated in different solvents. The results showed that PNIPAAm-g-Co-TDTAPc could dissolve in water and most organic solvents,while the small molecule cobalt phthaloyanine only dissolve in DMSO and DMF,which proved that the solubility of cobalt phthalocyanine was improved significantly after immobilization on PNIPAAm. The thermosensitive property of PNIPAAm-g-Co-TDTAPc was investigated by cloud point measurements, and the results showed that PNIPAAm-g-Co-TDTAPc exhibited excellent thermosensitive property in aqueous solutions, and its LCST was 34.5℃.The LCST of PNIPAAm-g-Co-TDTAPc in the mixture of water and organic solvents (ethanol and DMF) was also studied, and the experimental results showed that the LCST of PNIPAAm-g-Co-TDTAPc first decreased when the volume fraction of ethanol in mixed solvents increased below 27.5% and then sharply increased above 59.5% until the thermosensitivity of PNIPAAm-g-Co-TDTAPc disappeared. The experimental results in DMF/water mixed solvents were similar to those in water/ethanol. Furthermore, the catalytic activity of PNIPAAm-g-Co-TDTAPc on 2-mercaptoethanol was investigated by the consumption of oxygen at different temperature and pH 11.The results indicated that PNIPAAm-g-Co-TDTAPc had a high catalytic oxidation activity on 2-mercaptoethanol,and the reaction rate was first increased with the temperature increasing and then rapidly decreased when temperature was over LCST due to the precipitation of this catalyst from the solution. In conclusion, a novel high efficient polymer catalyst was prepared, which has both good solubility and excellent thermosensitive properties. Based on the above properties, it can be served as a homogeneous catalyst and separated just by heating, having potential applications in the fields of organic synthesis and degradation of organic pollutants.
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发布时间：2021-03-19 - 摘要：The efficient synthesis of poly(isobutylene-b-α-methylstyrene) (PIB-b-PαMeSt) copolymer has been accomplished by living cationic polymerization using sequential monomer additions. Living PIB was first prepared by the 2-chloro-2,4,4-trimethylpentane (TMPCl)/TiCl4/DtBP/C6H12∶MeCl=50∶50V/V/-80℃ polymerization system. Subsequently, the living PIB chain end was converted to the corresponding diphenylalkyl end by capping with 1,1-di-p-tolylethylene (DTE).Ti(OiPr)4 was added to reduce the Lewis acidity, followed by the addition of α-MeSt. When Ti(OiPr)4 was introduced into the polymerization system, the complexes of Ti2C 8-x(OiPr)x were formed rapidly. By changing the stoichiometry, the Lewis acidity of TiCl4 can be moderated in a wide range. This was corroborated by our visual observation that upon addition of Ti(OiPr)4 the orange color of the diphenyl carbenium ion turned into the yellow-green color. This indicated that highly reactive species convert into less reactive species. The PIB-b-PαMeSt copolymers were characterized by 1H-NMR spectroscopy and triple detection SEC: refractive index (RI),multi-angle laser light scattering (MALLS) and ultraviolet (UV) detector. The effects of the polymerization time for α-MeSt (t2) on conversion of monomer, dn/dc value, molecular weight and molecular weight distribution as well as the effect of Ti(OiPr)4 concentrations on the polymerization rate were investigated. The results showed that the dn/dc values of block copolymers increased with increasing poly α MeSt compositions. And molecular weight distributions of the resulting polymers stayed relatively narrow,less than 1.2 (MWD≤1.2).LS,RI and UV traces of the resulting PIB-b-PαMeSt copolymer had the same eluting time without any tailing which demonstrated the blocking efficiency is close to 100%.The kinetics of the cationic polymerization of α-MeSt in the presence of Ti(OiPr)4 were determined by the gravimetric monitoring of the polymer yield as a function of the reaction time.The monomer conversion gradually increased with increasing polymerization time,and the conversion decreased with increasing ［Ti(OiPr)4］/［TiC4］ ratio.Interestingly,there was a precipitous drop in conversion at ［Ti(OiPr)4］/［TiCl4］ ratio 1,with the 1.1 ［Ti(OiPr)4］/［TiCl4］ ratio ca. 5% conversion was obtained in 1 h.On the basis of these observations,it was concluded that Lewis acidity of TiCl4 decreased with increasing the ［Ti(OiPr)4］ to ［TiCl4］ ratio. When the ［Ti(OiPr)4］ to ［TiCl4］ ratio was more than 1.1,a slight excess of Ti(OiPr)4 deactivated TiCl4, and the active species lost.Linear plots of ln(［M］0/［M］) versus time passed through the origin demonstrated the expected first-order dependence on the monomer concentration, which proved that the concentration of growing centers remained constant.The result combined with the linear Mn-conversion plots confirmed that the polymerization was living.The kappP values obtained from the slope of the in(［M］0/［M］) versus time linear plots also showed that the rate of the polymerization decreased with increasing ［Ti(OiPr)4］/［TiCl4］ ratio.The complexes of Ti2Cl8-x(OiPr)x interacted with the growing chain end to reduce its“cationicity" and thus to decrease the polymerization rate,suppress chain transfer and termination reactions and narrow MWD.Differential scanning calorimetry (DSC) of the diblock copolymers showed two glass transitions demonstrating microphases separation.
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发布时间：2021-03-19 - 摘要：Three kinds of nickelbased complexes bearing o-hydroxyaryl N-heterocyclic carbenes ［C,O］ bidentate ligands were prepared via facile synthesis method. The polymerizations of norbornene were carried out using these complexes activated with methylalminoxane (MAO). The polynorbornenes obtained are soluble at room temperature in the solvents such as cyclohexane, chlorobenzene and so on. The influence of the catalyst structure on the catalytic activity,molecular weight and molecular weight distribution of the polynorbornene was investigated.The steric and electronic effects of nickel-based complexes bearing o-hydroxyaryl N-heterocyclic carbenes ［C,O］ bidentate ligands made the resultant polymers possess high molecular weight and narrow molecular weight distribution. Under the conditions such as the reaction temperature of 0℃,the reaction time of 10 min, molar ratio of aluminum to nickel of 2000 and molar ratio of norbornene to nickel of 75000,the complexes 1,2 and 3 activated with MAO show relatively high catalytic activity as 7.6×106 g PNBE/(molNi.h),13.4×10.6 g PNBE/(molNi.h) and 8.8×106 g PNBE/(molNi.h), respectively.The weight-average molecular weights of polymers attained are varied from 20.0×105 to 2.0×105, and molecular weight distributions ranged from 3.3 to 1.5.The complexe 2 was investigated in detail for the influence on the catalytic activity, molecular weight and molecular weight distribution as well.The catalytic activity was decreased from 8.1×106 g PNBE/(molNi.h) to 4.6×106 g PNBE/(molNi.h) when the polymerization temperature was varied from 0℃ to 90℃,which revealed that the catalyst is stable.The weight-average molecular weights of polynorbornenes were decreased obviously from 2.1×106 to 2.9×105 with the temperature increase from 0℃ to 90℃ while the molecular weight distributions were varied from 2.3 to 1.8 at the same temperature range. Norbornenes were polymerized rapidly when the molar ratio of aluminum to nickel was from 1000 to 3500.However,the molecular weight and molecular weight distribution were changed hardly which indicated that chain transfer reaction to MAO did not occur. Thermo-gravimetric analysis signified that all of the polymers were stable at about 400℃ under nitrogen. Attempt to determine the glass transition temperature of polynobornene from DSC was failed, and DSC studies did not give an endothermic signal upon heating to the decomposition temperature. The polynobornenes were characterized by GPC, 13C-NMR, FTIR,TG,DSC and WAXD. All of the resultant polymers showed similar FTIR and 13C-NMR spectra.The FTIR spectrum revealed no traces of double bonds, ensuring the occurrence of vinyl-type polymerization rather than ring-opening metathesis. 13C-NMR spectrum also further confirmed that the polymerization occurred via viny1-addition type polymerization (i.e. a 2,3-linked polymer); no ring-opened product was observed.Partial information on the conformation for the polynobornenes obtained by all the nickelbased complexes was obtained by means of wide-angle X-ray diffraction (WAXD).According to WAXD spectra,no traces of Bragg reflection were appeared. The polynobornenes, therefore,are non-crystalline, but similarly the polymers had short-range order and with high packing density.
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发布时间：2021-03-19 - 摘要：A kind of new functional polymeric microspheres with strong adsorption ability for creatinine was prepared, and the adsorption mechanism was studied in depth. First of all, the crosslinked copolymer microspheres of 2-hydroxyethyl methacrylate (HEMA) and N-vinylpyrrolidone (NVP) with an average diameter of 180 μm were prepared by suspension copolymerization and denoted as HEMA/NVP, which has biocompatibility. In the suspension copolymerization system, N,N′-methylene biscrylamide (MBA) was used as crosslinking agent, α,α′-azoisobisbutyronitrile (AIBN) was used as initiator, and Span-60 (Sorbitan monooleate) was used as suspension stabilizer. Subsequently, the microspheres HEMA/NVP were chemically modified with 3,5-dinitrobenzoyl chloride (DNBC), and the functional microspheres DNBZ-HEMA/NVP, on which a number of 3,5-dinitrobenzoate (DNBZ) groups were bonded, were obtained. In the modification reaction, triethylamine was used as the agent to capture acid, and reaction could be carried out favourably. The chemical structure and composition of the functional microspheres were characterized with FTIR and chemical analytical method. The adsorption characteristics of DNBZ-HEMA/NVP for creatinine were studied, and the effects of various factors on the adsorption properties of the functional microspheres were investigated. Static adsorption experiments show that the functional microspheres DNBZ-HEMA/NVP have strong adsorption property for creatinine due to the chemical reaction analogous to Jaffe′ reaction between 3,5-dinitrobenzoate on the surface of the microspheres and creatinine. In the aqueous solution, creatinine has two kinds of tautomers, the keto form and the enol form. The tautomer with enol form is easy to loss a proton and produces a negative oxyanion. The negative oxyanions are attracted by the nitrogen atoms with positive electricity on the nitro groups of DNBZ. Finally, a complex reaction takes place and a complex of 1∶1σ is formed between DNBZ of the microspheres and the creatinine molecule. Obviously, the adsorption of the functional microsphere DNBZ-HEMA/NVP for creatinine is attributed to chemical adsorption, furthermore, it is a chemical adsorption driven by electrostatic interaction. The adsorption capacity of DNBZ-HEMA/NVP is enhanced 20 times as compared with that of the unmodified microsphere HEMA/NVP, and the saturated adsorption amount reaches 21 mg/g. Both pH value and salinity influence the adsorption capacity greatly. As pH value of the medium is lower, creatinine exists mainly as keto form, and there are few negative oxyanions, so there is weak electrostatic interaction between the microsphere DNBZ-HEMA/NVP and the creatinine molecule resulting in the poor adsorption ability of the microsphere DNBZ-HEMA/NVP for creatinine and lower adsorption capacity. With the increase of pH value, the equilibrium between the two tautomers of creatinine moves to enol form, and more negative oxyanions will be produced. So the electrostatic interaction is strengthened, resulting in the stronger adsorption ability of the microsphere DNBZ-HEMA/NVP for creatinine and higher adsorption capacity. However, the too high pH value is also disadvantageous to the electrostatic interaction. The experimental results show that as pH=8.5, there is the strongest electrostatic interaction between the microsphere DNBZ-HEMA/NVP and the creatinine molecule, resulting in a maximum adsorption capacity. The ionic strength weakens the lectrostatic interaction, so greater salinity leads to decreasing the adsorption ability of the microsphere DNBZ-HEMA/NVP for creatinine.
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发布时间：2021-03-19 - 摘要：High refractive index organic/inorganic hybrid films have attracted considerable attention in both fundamental and applied research as hard coatings for organic resins.Among these hybrid materials,TiO2 is a typical candidate for hybrid components due to its high refractive index and hardness. In this article, a series of titania containing organic/inorganic hybrid films with high refractive index and performance were prepared by co-hydrolysis of silane coupling agent (3-glycidyloxypropyl) trimethoxysilane (KH-560) and titanium butoxide ［Ti(OBu)4］ through sol-gel method without using any stabilizer.Our method improved the optical and mechanical properties of the resultant hybrid coatings.The microstructure,optical,mechanical and thermal properties of the hybrid films were characterized by using different methods. FTIR indicates that the different components have been successfully combined to hybrids by covalent bonds.TGA indicates these hybrid films have good thermal durability.AFM and TEM indicate that the films have smooth surface, and the titania nano-phases (3 nm) were well dispersed in all the films without aggregations even in the film with high titania content.UV-Vis transmission spectra indicate that the hybrid films have high transparency of above 90% in the range of visible light,which is in accordance with AFM and TEM results.In addition,the refractive index of the hybrid films could be adjusted linearly from 1.5 to 1.7 by altering the titania content.The pencil hardness of the films is 4～5 H both before and after aging, and all the films have good adhesion performance to substrate materials.The hybrid films have potential applications in filters,optical waveguide,lenses and antireflection films.
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发布时间：2021-03-19 - 摘要：The analysis of the cure induced phase separation time/temperature dependence of thermoplastics (TP) modified thermosetting (TS) systems is necessary in the cure routine design process so as to optimize the final material mechanical properties. We found the cure induced phase separation time/temperature can well be described with the Arrhenius equation; the phase separation activation energy Ea(ps) generated from Arrhenius equation is not affected by the TP content, TP molecular weight,cure rate or phase separation detection means, and the chemical environments is presumed to play a vital role on Ea(ps).How the chemical environment will affect the miscibility between TP and TS species and further the phase separation activation energy Ea(ps),there is no theoretical or experimental work on such problems. In this paper, we make a detail analysis on the question how the chemical environments changes along the TP or TS chemical structure, and how the Ea(ps) is related to the chemical environments. As part of our serious work, our main focus here is on some TP/TS systems which show upper critical solution temperature (UCST) type phase behavior. The component chemical structures of thermoplastics, thermosets, crosslink agent and stoichiometric ratio etc. were changed in certain way,the corresponding cure induced phase separation activation energy were determined in a wide time-temperature window. The TP and TS species employed here are poly(ether imide), epoxy, cyanate ester, diamine and anhydride. The study is carried out by means of transmission optical microscopy and differential scanning calorimetry. The results indicate that the phase separation activation energy Ea(ps) varied with the structures of thermoplastics,thermosetting monomers and crosslink agent,and also changed with the stoichiometric ratio. Ea(ps) decreases with the increase of EEW (epoxy equivalent weight) of DGEBA monomers. The structure of thermoplastic PEI also shows a remarkable effect on Ea(ps),the systems with PEI bearing large stereo obstacle groups favoring miscibility of the TP and TS present higher Ea(ps). At the same time Ea(ps) increases with the content of crosslink agent of DDM and MTHPA,while decrease with the content of DDS. The change of Ea(ps) with the chemical structure of the component can be explained in view of the interaction energy density theory which based on the Hildebrand-Scatchard regular solution theory. By calculation of the interaction activation energy density with the solubility parameter, it was found that the factors unfavoring miscibility between TP and TS species will decrease the value of Ea(ps),while those factors favoring miscibility of the systems will increase the value of Ea(ps), some systems with very small value of interaction energy density parameter will not show phase separation throughout the cure reaction. The phase separation diagram of thermoplastics with thermosetting oligomers can verify the interaction energy density approach in understanding the change of Ea(ps) with chemical structure of the components.
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发布时间：2021-03-19 - 摘要：An amphiphilic star block copolymer (star-PCL-b-PEG) based on dendritic poly(ether-amide)(DPEA) was prepared through ring opening polymerization of εcaprolactone (CL) with a DPEA-OH dendrimer as an initiator,then coupling with isocyanate terminated linear polyethylene glycol(PEG-NCO).The molecular structure was verified by FT-IR, 1H-NMR and GPC.The polymer could form micellelike nanoparticles due to its amphiphilic characteristics.The aggregates of star-PCL-b-PEG in aqueous media were fabricated by dropping deionized water into block copolymer solutions in common solvents.The micellar characteristics of star-PCL-b-PEG in water were similar to those of “crew-cut" aggregates. The star-PCL-b-PEG block copolymer was investigated by fluorescence spectroscopy,dynamic light scattering(DLS) and transmission electron microscopy(TEM).The critical micelle concentration (CMC) was determined by a fluorescence technique to be 1.623 mg/L.The hydrodynamic radius of micelles was measured to be 86.2 nm or 224.6 nm at different concentrations by DLS，and the polydispersity index(PDI) was estimated to be 0.115 and 0.197,respectively,showing that the particle size was relatively widely distributed at the higher concentration.As the concentration of copolymer increased,the more hydrophobic PCL segments easily aggregated with each other due to the hydrophobic interaction.Therefore,the polymer particles were formed from a lot of molecules. The morphology of star-PCL-b-PEG “crewcut" aggregates was studied directly by TEM, and various morphologies of crew-cut micelle-like aggregates were observed under various conditions by changing the nature of common solvents,the initial copolymer concentration and the water content. The multiple morphologies, including spheres,robs and vesicles were obtained.It was found that spheres and robs were obtained from the star-PCL-b-PEG solutions with THF as the common solvent, while vesicles were obtained from the copolymer solutions with DMF as the common solvent.
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发布时间：2021-03-19 - 摘要：Three novel monomers were synthesized and confirmed by FT-IR and 1H-NMR. N,N′-(4,4′-diphenyl-methane)bistrimellitimide diacid chloride (DIDC-M) was synthesized by acidylated the 4,4′-bis(N-Trimellitimide)-diphenylmethane,which obtained from trimellitic anhydride with 4,4′-diaminodiphenylmethane (DDM).2,2′,6,6′-Tetremethyl-4,4′-diphenoxy diphenylketone(o-Me2-DPOBP) and 2,2′,6,6′-tetremethyl-4,4′-diphenoxy-triphenyldiketone (o-Me2-DPOTPDK) were prepared by aromatic nucleophilic substitution reaction by 2,6-dimethylphenol with 4,4′-difluorodiphenylketone and 4,4′-difluorotriphenyldiketone respectively at the presence of sodium hydroxide,using DMSO as solvent at 200℃.Two novel poly(aryl ether ketone imide) copolymers containing bis(o-methyl) moieties were prepared by low temperature solution polycondensation of DIDC-M with o-Me2-DPOBP or o-Me2-DPOTPDK,in 1,2-dichloroethane (DCE) and at the presence of AlCl3 and N-methyl-2-pyrrolidone (NMP) as catalyst.The structure of copolymers (Pa,Pb) obtained were characterized by FTIR and 1H-NMR.Differential scanning calorimetry(DSC) analysis indicated that the copolymers showed high glass transition temperature (Tg) 240℃ and 237℃,respectively.The single Tg’s in the DSC cures suggested that no microphase separation occurred in the block copolymer.The copolymer also showed a high thermal stability with 5% weight-loss temperatures in excess of 464℃ in nitrogen,while 10% weight-loss temperature over 513℃,according to thermogravimetric analysis (TG).Wide-angle X-ray diffraction (WAXD) studies revealed that Pa and Pb were amorphous,which agreed with the results of DSC,and as a result of introducing the rigid imido structure or non-planar methyl pendent to polymer backbone,the regularity of macromolecular chain destroyed.The soluble behaviours of the copolymers were tested qualitatively at room temperature in common organic solvents.It showed that the copolymers have good solubility in the following solvents, N,N-dimethylformamide (DMF),N,N-dimethylacetamide (DMAc), NMP, dichloromethane,tetrechloroethane and chloroform. Flexible and colorless films were easily obtained by solution casting with DMAc as solvent.Tensile strength, elongation at break and Young’s module of Pa were 80.0 MPa,6.95%,and 2.0 GPa, respectively,and for Pb were 51.8 MPa,4.6%,and 1.8 GPa,respectively.So introducing methyl pendent groups in the polymer main chain and copolymerization with novel monomers are efficient methods to synthesis high performance advanced materials. Furthermore,the copolymers contain methyl pendant group as a potential functional group,which can be converted into aldehyde or carboxylic acid,so it provides an original way to prepare functional PI/PEK copolymer’s.
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发布时间：2021-03-19
Research Article
- 摘要：In order to improve the properties of SiC ceramic fibers polyzirconocarbosilane (PZCS),the precursor of Si—Zr—C—O ceramic fibers, was synthesized by the reaction of zirconium acetylacetonate (Zr(AcAc)4) at 420℃ with polysilacarbosilane (PSCS),which was prepared by the thermolysis and condensation of polydimethylsilane (PDMS).By the use of liquid PSCS,Zr could be distributed uniformly,and the sublimation of Zr(AcAc)4 could also be avoided.The empirical formula of PZCS was SiC1.94HxO0.066Zr0.0104,the number-averaged molecular weight is in the range of 1300～2500.When the reaction of PSCS with Zr(AcAc)4 proceeded,an enormous decrease in the number of Si—H bonds in PSCS was observed.The reaction mechanism was found to be that the increase of the molecular weight of PZCS was related to the cross-linking reaction of Si—H bonds with Zr(AcAc)4,which led to the generation of Si—O—Zr.There exists SiC4 and SiC3H structure in PZCS.The ceramic yield of PZCS was 82.4%.We got the Si—Zr—C—O ceramic fibers using PZCS,whose chemical formula was SiC1.24HxO0.56Zr0.0129.The average tensile strength was 2.6 GPa,the average diameter was 11 μm.Si—Zr—C—O fibers have good hightemperatureresistant performance.Processing at 1450℃ and 1600℃,the tensile strength retention rate was 72% and 36% respectively.Si—Zr—C—O fibers also have good oxidation-resistance properties.After processing 20 h at 1000℃ in the air,the tensile strength retention rate was 71.2%,after processing 100 h,the tensile strength retention rate was 50%.
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发布时间：2021-03-19 - 摘要：A novel approach to chelating aurum (Au) by modified polypropylene (PP) was developed. Photo-induced grafting polymerization of acrylic acid (AA) on PP was carried out first, followed by anionic ring-opening polymerization of caprolactam on the above modified film to introduce PA6 chains onto the PP films.By this method,functional groups containing N and O were introduced on PP films. Because these functional groups and chloroauric acid formed the ion-association complex in acid solution, the prepared PP film was used to chelate Au. The obtained films after each treatment step were characterized with attenuated total reflectance (ATR)IR spectroscopy, scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) techniques.After chelating Au,the concentration of Au in the solution decreased from 1 mg/mL to 2.58 μg/mL. The results showed that the films prepared possessed good effect on chelating Au. This study suggested a new approach of chelating Au by modified PP which may have potential applications in reclaiming noble metals from smelt waste water.
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发布时间：2021-03-19 - 摘要：The copolymerization of norbornene (NB) with methyl acrylate (MA) in the presence of iron (Ⅲ) acetylacetonate ［Fe(acac)3］ associated with a triisobutylaluminum ［Al(i-Bu)3］ catalyst system was investigated.The polymerization was carried out under dry nitrogen in toluene in a glass flask equipped with a rubber septum.For preparing the catalyst system Fe(acac)3 was first dissolved in the reaction solvent, and Al(i-Bu)3 was then added. The monomers were first dissolved in the reaction solvent, and the catalyst was introduced to initiate the polymerization. After a given reaction time, the polymerization mixture was poured into a large amount of methanol containing a few percent of hydrochloric acid to precipitate the polymer. The liquid phase was filtered, and the recovered polymer was dried in vacuo. The characteristics of copolymerization of norbornene and methyl acrylate by Fe(acac)3- Al(i-Bu)3 were studied. T he copolymers were characterized by FTIR,13C-NMR,GPC and elementary analysis. Copolymers with NB content of 12.3 mol%,19.5 mol% and 26.0 mol%,respectively were prepared. The molecular weight of the copolymers was in the range of 0.52×10.5～1.05×10.5,and its distribution index Mw/Mn was in the range of 2.25～2.67. They both decreased with increasing the molar ratio of NB/MA. The copolymerization can be performed in the solvents such as aromatic hydrocarbons. The third composition could exert influence on the copolymerization. The yield of copolymers with a third composition like carbon tetrachloride or 1,4-dioxane and triphenylphosphine was higher than that of copolymers without the third composition. However, the addition of 1,10-phenanthroline or 8-hydroxy quinoline and α,α′-dipyridine decreased the yield. The copolymerization could be obtained at room temperatures, however, increasing reaction temperature caused an increase of the copolymer yield. The yield of copolymer was also changed with the change of Al/Fe molar ratio,and the suitable Al/Fe molar ratio was 25. The copolymer can form porous membrane on cover glass automatically with pore size of 7～15 μm during evaporation of THF from the copolymer solution at room temperature.
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发布时间：2021-03-19
Research Bulletin
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