最新刊期
卷 ， 期 6 ， 2010
- 摘要：A novel enzyme responsive amphiphilic copolymer was synthesized.The copolymer was composed of hydrophobic polylactide (PLA) and hydrophilic αmethoxy-poly(ethyl glycol) (MPEG) block.The two blocks were conjugated through 5,5′-azodisalylic acid (OLZ) (MPEG-OLZ-b-PLA).The chemical structure of the copolymer was verified by FTIR,NMR and GPC.The NMR characterization demonstrated that the copolymers could be synthesized by esterification and purified by precipitation and dialysis.The micellization behavior of the copolymer in aqueous media was studied with transmission electron microscopy (TEM) and dynamic light scattering (DLS).The results showed that MPEG-OLZ-b-PLA self-assembled into spherical micelles with diameter at about 30 nm.The critical micelle concentration (CMC) of the copolymer was 2.69×10-3 g/L.The enzyme-degradation experiment demonstrated that the MPEG-OLZ-b-PLA micelles could be specifically degraded in rat cecum contents.And the degradation curve had two time platform with no change in azo content.The first platform phase resulted from the induction period of the enzyme so that desirable concentration of the enzyme could be achieved for initialing the degradation of the copolymers.The second could be attributed to the slow dynamic process for azoreductase to migrate into the micelles.Such degradation behavior of the copolymers suggested of potential usefulness to colon-site specific delivery.
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发布时间：2021-03-19
Rapid Communications
- 摘要：Five novel poly(aryl ether ketone ketone ether ketone ketone) with carboxylic ester side groups (PEKKEKK-E)s were synthesized from poly(aryl ether ketone ketone ether ketone ketone) having pendent carboxyl groups (PEKKEKK-A) and alcohols,in the presence of 1,2-dichoroethane and thionyl chloride as acylchlorination reagent,pyridine as a catalyst.While PEKKEKK-A was prepared from trimellitic anhydride chloride (TMAC) and 1,4-bis(4-phenoxybenzoyl)benzene(p-EKKE) by low temperature solution polycondensation.PEKKEKKEs were characterized by FTIR,1H-NMR,WAXD,TGA,DSC,the solubility and mechanical properties of the polymers were investigated.Results show that the glass transition of the polymers is in the range of 175℃ to 237℃.The structure of the polymers is amorphous as expected.The esterified polymers have better solubility than the corresponding polymer.Flexible and colorless films were easily obtained by solution casting taking DMAc as solvent.It shows that the polymers have good mechanical properties.Tensile strength,elongation at break and Young’s module of polymers are in the range of 74.7 MPa to 85.4 MPa,6.34% to 15.43%,and 1.74 GPa to 3.08 GPa,respectively.
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发布时间：2021-03-19 - 摘要：The interfacial structure between SU-8 photoresist and Ni substrate was constructed by using molecular dynamics (MD) simulation software Materials Studio.The influence of postbaking temperature on the interfacial binding property was studied.According to postbaking temperature adopted by experimental process,cross-linking reaction of SU-8 photoresist was performed at different postbaking temperatures within 338～368 K.Several circles of energy minimization (MM) and MD simulation were applied to the interfacial structure.The binding energy was calculated after the interfacial system getting equalization.It can be seen that with increasing the postbaking temperature the binding energy of the interface between SU-8 photoresist and Ni substrate becomes larger.The value of the binding energy achieved maximum at 368 K.So it can draw the conclusion that the binding property is best at this temperature.By analysing the energy of the molecular system,it can be found that the key influencing factor for the interfacial adhesion is van der Waals force between interface molecules.Pair correlation function (PCF) between atoms of the interfacial structure was analysed.Two strong peaks were found in the range of 0.31 nm to 0.6 nm which belonged to the range of van der Waals force.
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发布时间：2021-03-19 - 摘要：A series of phosphorus and silica-containing hybrids (DPS) with different molecular weight was synthesized by hydrolysis condensation of intermediate products and various amounts of water.The intermediate was formed by the reaction between 3-glycidyloxypropyltrimethaxysilane (KH-560) and diethyl phosphate (DEP) in different weight ratios.The structure of DPS was determined by Fourier transform infrared (FTIR),nuclear magnetic spectrum (NMR) and element analysis,while molecular weight and distribution of DPS were measured by gel permeation chromatography (GPC).Then,a cured epoxy resin containing phosphorus and silica-containing hybrid was prepared by the in situ curing of the bisphenon A type epoxy resin and 4,4′-diaminodiphenylmethane with the phosphorus and silica-containing hybrid.The flame retardation was investigated by the limited oxygen index (LOI),and the thermal properties of the cured epoxy resin were characterized by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA).Studies on the characteristics of cured epoxy resin containing a phosphorus-and silica-containing hybrid showed that the flame retardant and the thermal properties were enhanced.The flame resistance was indicated by the limited oxygen index in the ranges of 23～29,which was higher than that of the pure epoxy resin (22).The glass translation temperature for E54-Si-3H-20 sample was 204℃ and the temperature of 5% weight loss was about 20℃ higher than that of the pure epoxy resins.Compared to the pure epoxy resin,not only the flame resistance of the cured epoxy resin containing phosphorus,silica-containing hybrid was enhanced,but also the thermal properties were improved.
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发布时间：2021-03-19 -
COORDINATION POLYMERIZATION OF 1,3-BUTADIENE WITH Ni(naph)2/A1R3/BF3·OEt2/DMEA/OctOH CATALYST SYSTEM
摘要：The coordination polymerization of 1,3-butadiene was conducted with Ni(naph)2/A1R3/BF3·OEt2 catalyst system in the presence of N,N-dimethyl ethanolamine (DMEA) and octanol (OctOH) in hexane at 50℃.The effects of molar ratios of DMEA/Ni,B/Ni and Al/Ni on monomer conversion,intrinsic viscosity (［η］),molecular weight,molecular weight distribution and microstructure of polybutadiene (PB) were investigated.The kinetic study was also conducted for this polymerization at different temperatures ranging from 20℃ to 50℃.The results showed that DMEA and OctOH played very important roles in modifying molecular weight,molecular weight distribution and microstructure.By comparison,the molecular weight of polybutadiene products could be greatly increased,molecular weight distribution narrowed and cis1,4 content of Bd units in polymer chain increased to 97.8% and 1,2-content decreased to 1.3% by introducing adequate amounts of DMEA and OctOH,leading to more crystalline and less gel content.Furthermore,the intrinsic viscosity (［η］) of polymer products could also be modulated by changing the molar ratios of B/Ni and Al/Ni in the range of 2.0 ~ 4.0 dL/g.The polymerization was in first order with respect to monomer concentration at different polymerization temperatures.The apparent activation energy for propagation was determined to be 43.7 kJ·mol-1.- 18
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发布时间：2021-03-19 - 摘要：Aim to explore the polymer crystallization during the cooling stage,a multiscale model in which macroscopic temperature and microscopic crystal morphology are related with each other is built up.On the one hand,the variation of macroscopic temperature can bring in changes of nucleation number and growth rate of crystal,and thus results in changes of microscopic crystal morphology.On the other hand,the latent heat released by crystallization can cause significant rise of temperature with the evolution of the crystallization.According to this multiscale model,the algorithm of coupling finite volume method with pixel method is proposed.The finite volume method is used on the coarse grid to calculate the macroscopic temperature and the pixel method is employed on the fine grid to capture the morphology of crystallization.A 2\|D polymer melt with its boundaries experiencing the constant cooling rate operation is studied and the temperatures,relative crystallinity as well as the evolution of crystal morphology are given.In addition,the roles of cooling rate and initial temperature are also discussed.The results indicate that cooling rate is a significant factor for the temperature,relative crystallinity as well as the morphology.In the case of higher cooling rate,the plateau of temperature turns on earlier and lasts shorter,and so does the relative crystallinity; the temperature which begins with the crystallization does not change,however,the range of temperature becomes wider; due to this wider temperature change,nucleation number becomes more,thus result in the smaller average crystal size.The initial temperature only affect the time of showing up of temperature plateau and crystallization,and is almost independent on the lasted time.
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发布时间：2021-03-19 - 摘要：Three different poly(vinyl chloride) (PVC) formulations were submitted to photo ageing.The influence of the different thermal stabilizers was evaluated by means of ultraviolet-visible (UV-Vis) spectra,fourier transform infrared (FTIR) spectra and differential scanning calorimetry (DSC).The gel content formed in exposed samples was estimated gravimetrically,and the color and mechanical properties changes of PVC during photoageing were studied.It was found that microstructures of three PVC/thermal stabilizer blends changed in the same tendency.As UV irradiation time increases,the conjugated polyene sequence,carbonyl group and the gel content increase,respectively.And the molecular weight decreases.Meanwhile,the yellowness index,the elongation at break and impact strength of the PVC sheets gradually decrease with increasing UV irradiation time.The main photochemical reactions include photo-dehydrochlorination,photooxidation,degradation and crosslinking.The degree and the kinetics of dehydrochlorination,oxidative,degradation and crosslinking during photoageing were different in three PVC/thermal stabilizer blends.Sn was the most efficient on restraining dehydrochlorination.Pb was the most stable in the reaction of oxidative degradation and crosslinking.As a result PVC/Sn blends showed higher color stability,and the retained percentage of impact strength and elongation at break of PVC/Pb blends were the highest among of the three blends.
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发布时间：2021-03-19 - 摘要：Poly［(hexafluoroisopropyloxy)2-x(trifluoroethoxy)x］phosphazene with different substituent ratios was synthesized.The final substituted polyphosphazene products were purified through the THFbenzene precipitation to remove impurity. 31P-NMR was used to assure the purification.The structure of this polymer was characterized by 1H\|NMR,FTIR,XRD,GPC and DSC.Gas permeability coefficients of N2,O2,CH4,CO2,He,H2 in these polymers at 20℃ were measured by the permeate gas pressure method.The trifloroethoxy group showed more competitive substitution than hexafluoroisopropyloxy under same nucleophilic substituted reaction condition.The x-value of three different poly［(hexafluoroisopropyloxy)2-x(trifluoroethoxy)x］phosphazene products were 1.64,1.72 and 1.81 respectively.The glass transition temperature of these polymers were -20.21℃,-42.83℃ and -43.41℃,and the weight\|average molecular weight were 5.07×105,1.49×105and 2.69×105,respectively.These polymers showed higher gas permeability.Its permeability coefficient of N2,CO2 and He were 20 barrer,124 barrer and 85 barrer respectively,and the selectivity coefficient of CO2/CH4 and He/CH4 were 11.5 and 4.8,which showed great potentiality to be applied in natural gas industry.In addition,the selectivity coefficient of H2/N2 was 5.8,the permeability coefficient of H2was 43 barrer,which also showed special potentiality in ammonia synthesis industry.
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发布时间：2021-03-19 - 摘要：Polyethylene glycol (PEG) with flexible chains was blended with cationexchange membrane carboxymethyl cellulose (CMC) and anion-exchange membrane chitosan (CS) in order to enhance the compatibility and mechanical properties. Then CMC and CS were modified by Copper multicarboxylphthalocyanine (CuPc) and acetyl ferrocene respectively. CuPcmCMC/mCS bipolar membranes were prepared by a pasting method. The metallophthalocyanine derivatives were combined with the molecular chains in the membranes to form the net structure. The structure stability of the interlayers and the dimensional stability were increased. The results of swelling degree and TGA show that the properties of CuPc-mCMC/mCS bipolar membranes are improved after modification. The CuPc-mCMC/mCS bipolar membranes show good thermal stability until 150℃, which is available to be used in the organic electrosynthesis. Both of the membrane impedance and the working voltage of CuPc-mCMC/mCS bipolar membranes are small. The working voltage is as low as 3.0 V during the curreuring density at around 45 mA/cm2. The —COOH groups in the metallophthalocyanine derivatives as the ion transmission media accelerate the transfer rate of ions, and the CuPcmCMC/mCS bipolar membrane exhibits a higher ion penetrability after modification.
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发布时间：2021-03-19 - 摘要：A highly selective molecularly imprinted polymer (MIP) was prepared by a simple molecular imprinting technique with a sol-gel process. Erythromycin was used as template, 3-aminopropyltrimethoxysilane (APTMS) as functional monomer and tetraethylorthosilicate (TEOS) as reticulating agent. Infrared spectroscopy, scanning electron microscopy, thermogravimetric and surface area analyses were used to characterize the composite structure and morphology in detail. The results showed that the specific surface area of MIP was 266.2 m2/g. These imprinted polymer particles had perfect spherical shape with average size of 600 nm and exhibited especially selective recognition for erythromycin. Equilibrium binding experiment showed that the separation factor was 2.20 when erythromycin was separated by using MIP. The elution condition was optimized, and the optimal condition was methane: acetic acid (75∶25, V/V) as eluent, and the optimal elution volume was 15 mL. The recovery of erythromycin was 103.1% by using 15 mL mixture of methane: acetic acid (75∶25, V/V) as eluent. Packed in solid phase extraction column, the polymer was used to extract erythromycin from erythromycin enteric\|coated tablets. The results indicated that the polymer can separation and enrich erythromycin from erythromycin enteric\|coated tablets successfully with the recovery of 104.5%.
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发布时间：2021-03-19 - 摘要：Based on the microbond test, the method of sample preparation was improved, and its procedure was described in detail. The effect of interfacial parameters, such as the slope k(N/m) and intercept b(N) of the function Fmax(le), k′(N/m2) and b′(N/μm) of the function τIF(le), on the micromechanics of micro\|composites was discussed. The experimental results showed that typical maximal force (Fmax) demonstrated excellently linear relationship with embedded length (le) in range of 55 and 75 μm when the stretching rate was 4 mm/min. However, the interfacial shear strength (τIF) showed hyperbolic relationship with the le, and eventually tended to a limited value (k′) along with increase of le. At the same time, the interfacial parameters, slope k (from 0.0033 to 00095 N/m) and intercept b (from -0.54 to -0.14 N), were discussed respectively to reveal how these parameters affected the dispersion of theoretical curves. The bigger the value of k was, the faster the typical maximal force (Fmax) and the theoretical curve of the interfacial shear strength (τIF) increased. Meanwhile, the bigger the value of b was, the bigger the value of typical maximal force (Fmax) and interfacial shear strength (τ IF) were. Finally, the effect of specimen geometry on the dispersion of experimental data was also discussed. The defects of different specimens actually caused stress concentration in the interface, which increased the dispersion of experimental curves.关键词：Microbond test;Micromechanics;Interface;Micro\
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发布时间：2021-03-19 - 摘要：In order to synthesize cyanic RAFT agents for RAFT polymerization of methyl methacrylate (MMA),an improved aqueous phase method was developed to prepare di(thiocarbazolyl) disulfide (DTCD) with carbazole as main material and potassium ferrocyanide as oxidant.Compared with the traditional oilphase method,the expected high purity DTCD was obtained in the form of crystal that was precipitated and separated from the aqueous solution.Then,2-cyanoprop-2-yl N-carbazolylcarbodithioate (CYCBD) and 4-cyanovalericacid Ncarbazolylcarbodithioate (CVCBD) were synthesized based on a substitution reaction between DTCD and azobisisbutyronitrile (AIBN) or azobis(cyanovaleric acid) (ACVA).The activities of CYCBD and CVCBD as RAFT agents for the polymerizations of MMA were determined,and the results showed that both of the RAFT agents were of significant activity in the RAFT polymerization of MMA and molecular weight distribution of fluoresence\|labelled poly(methyl methanylate) CPMMA prepared by CYCBD or CVCBD is less than 1.2. The fluorescence characteristics of CYCBD and CVCBD as well as CPMMA prepared by CYCBD or CVCBD were also studied.The results showed that all of them exhibited significant fluorescence in tetrahydrofuran (THF) solution.Moreover,CPMMA prepared by CYCBD or CVCBD possesses obvious fluorescence emission at a wavelength of 358 nm,and there is a good linear relationship between fluorescence intensity and concentration of CPMMA when the concentration of CPMMA in the range of 01～20 μmol/L.In a word,CYCBD and CVCBD as RAFT agents possess good control ability and can be used to synthesize fluorescencelabelled polymers with well-defined structure.
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发布时间：2021-03-19 - 摘要：Sodium lignosulfonate(SL),recovered from spent pulping liquor,has been used as a polyanion to build up multilayer films through an electrostatic sequential adsorption process by using poly(diallyldimethylammonium chloride)(PDAC) as the polycation,and the effect of pH value on the electrostatic layer-by-layer self-assembly has also been studied in this work.The electrostatic sequential adsorption process was monitored by UV-Vis spectrosxopy,and the morphology of the SL/PDAC multilayers was observed by AFM.Results show that during the sequential adsorption process,the UV-Vis absorbance of the SL/PDAC multilayers increases linearly,indicating that the thickness of multilayes increases in a layer-by-layer manner.The solution pH has a significant influence on the thickness and morphology of the SL/PDAC multilayers.In the studied pH value range,the lower is the solution pH,the higher is the UV-Vis absorbance and the larger is the roughness of the multilayer films.This phenomenon is caused by the specific molecular structure of lignosulfonate,and its conformation characteristics in solutions with different pH values.The sodium lignosulfonate exhibits different ionization degrees in the solutions with different pH values,because it includes not only sulfuric groups,but also carboxylic and phenolic groups.Although sulfuric groups can ionize at any pH value,but the ionization degrees of carboxylic and phenolic groups in the solutions increase with increasing pH values.The higher absorbance and the larger roughness of the layer-by-layer films can be attributed to the low ionization degree and the shrinkage conformation of sodium lignosulfonate in the solution with the low pH value.This work is helpful for understanding the adsorption characteristics of SL at a molecular level,and further expanding functionalities of SL through manipulation of the adsorption capacity by changing solution pH values.
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发布时间：2021-03-19 - 摘要：Thermoresponsive and optically active polymer poly(N-acryloyl-L-valine N′-methylamide)(PAVMA-CCH) bearing amino acidamide moieties in the side chain was synthesized via reversible addition\|fragmentation chain transfer (RAFT) polymerization using 2\|dodecylsulfanylthiocarbonylsulfanyl-2-methyl\|propionic acid propargyl alcohol ester (DMPE) with alkyne group in the end as the chain transfer agent (CTA).Diblock copolymer MPEG-b-PAVMA was then prepared from “click” coupling reaction between PAVMA-CCH and polyethylene glycol monomethylether capped by azide group (MPEG115\|N3) in conjunction with CuSO4/ascorbate sodium as catalytic system.The chemical structures and molecular characters were evaluated by 1H-NMR and size exclusion chromatography (SEC),respectively.The number of repeating unit for MPEG and PAVMA was 115 and 55,respectively,which was calculated from 1H-NMR analysis.The lower critical solution temperatures (LCSTs) for PAVMA and MPEG-b-PAVMA in water were 6.5℃ and 19.5℃,respectively,which were measured by transmittance tests on a UV-Vis spectrophotometer equipped with a temperature controller system.Specific optical rotation results showed that optical activity of the prepared PAVMA-C≡CH homopolymer and corresponding MPEG-b-PAVMA copolymer decreased comparing with that of monomer (AVMA) due to the variation of micro\|conformation during polymerization.Circular dichroism (CD) spectra for the aqueous solution of resulted polymers at 5℃ exhibit a weak Cotton effect peak at about 220 nm and a strong negative Cotton effect peak at around 197 nm,indicating random coil conformation for polymer chains in solution.
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发布时间：2021-03-19 -
ELECTROCHEMICAL OXIDATION CROSS-LINKING REACTION OF POLY(FLUORENYLACRYLATE) AND ITS CHARACTERIZATION
摘要：High quality freestanding polyfluorene network films were synthesized successfully in CH2Cl2 containing additional 40%(by volume) boron trifluoride diethyl etherate (BFEE) by direct anodic oxidation of its precursor polymer,a polyacrylate functionalized with fluorene,which was first obtained through radical polymerization of fluorenyl acrylate.The possibility of inter and intramolecular oxidation cross\|linking resulted in a crosslinked conjugated network microstructure.UV-Visible and FTIR spectra were used to study the structures of the polymers,respectively.According to the UV-Visible spectra of FM,poly(fluorenyl acrylate) (PFM) and cross-linked poly(fluorenyl acrylate) (CPFM),the spectra of CPFM showed red-shifted absorption at 352 nm compared to those of FM and PFM,indicating higher conjugation length of the backbone of the polymer.In the FTIR spectrum of CPFM,three peaks at 800,754 and 720 cm-1 suggested that CPFM was 1,2,4trisubstituted.Furthermore,the maximum emission peak of PFM appeared at 346 nm while that of CPFM in solid state appeared at 415 nm,implying the blue-light emitting property of CPFM.Polyfluorene network films obtained from this medium showed good thermal stability.Scanning electron microscopic results indicated that network CPFM films composed of ordered nanostructures were obtained electrochemically in this paper.- 22
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发布时间：2021-03-19 - 摘要：The process of photopolymerization of polyethylene glycol diacrylate in supercritical carbon dioxide system was explored.Supercritical carbon dioxide was obtained in a high pressure chamber by adding carbon dioxide into the chamber and adjusting the temperature and pressure befittingly.Then carbon dioxide,and solution of reactive monomer and photo initiator were sprayed simultaneously into the high pressure chamber to form mist of the reactants interacting with carbon dioxide,and the further uniform dispersion system of reactant in supercritical carbon dioxide could be got by anti solvent effect.The results showed that the photopolymerization of active monomer in supercritical carbon dioxide performed successfully under irradiation of UV light resource as prospected and crosslinked polymer microparticles were produced.Furthermore,the relationship of the kind of solvent,the quantity of the reactants with the distribution properties of the microparticle size was investigated.It could be seen that the distribution of the microparticle size broadened with the decreasing of the solubility of the reactants in supercritical carbon dioxide which was caused by the larger polarity of the solvent and the poor solubility of the solvent in supercritical carbon dioxide.The results also showed that the distribution of the microparticle size increased with the increasing of quantity of the reactants.
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发布时间：2021-03-19 - 摘要：The graft polymerization of acrylonitrile on crosslinked polyvinyl alcohol (CPVA) microspheres was performed by using cerium ammonium sulfate as initiator,and grafted microspheres CPVA-g-PAN were prepared.Subsequently,the grafted PAN was converted into poly(amidoxime) (PAO) via amidoximation reaction with hydroxylamine hydrochloride as reagent,resulting in the functional microspheres CPVA-g-PAO.The chemical structure and physicochemistry characters of CPVA-g-PAO microspheres were adequately characterized by infrared spectrum (FTIR),scanning electron microscope (SEM) and determining zeta potential.The effects of main factors on the amidoximation transform reaction of the grafted PAN were studied with emphasis,and the adsorption property of the functional microspheres CPVA-g-PAO for some biomolecules was examined preliminarily with uric acid as a model biomolecule.The experimental results show that in the a midoximation transform reaction of nitrile groups,medium pH and reaction temperature are two main factors.For this system,the adequate pH value and temperature are 6～7 and 70℃.Under the fitting conditions,the conversion ratio of the nitrile group of the grafted PAN reaches 72% for 4 h.In a wider pH range,the zeta potential of the microspheres CPVA-g-PAO is a greater positive value.They exhibit strong adsorption ability for uric acid,a toxic endogenrsis molecule,and the adsorption capacity can get up to 95 mg/g.
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发布时间：2021-03-19 -
STEREOSPECIFIC ANIONIC POLYMERIZATION OF STYRENE IN THE PRESENCE OF BARIUM DODECYL BENZENE SULFONATE
摘要：The anionic polymerization of styrene has been studied using dodecyl benzene sulfonic acid barium salt(SDBB)/tetrahydrofuran as ligands,nBuLi as initiator in cyclohexane.The results showed the remarkable effect of SDBB on polymerization. With increasing ［SDBB］/［Li］, the polymerization rate and monomer conversion decreased, and the gel formed gradually. The polymerization was completely retarded at ［SDBB］/［Li］ ≥ 0.8 at 60℃.The stereospecific polystyrene was obtained at 60℃,and its weight content of methyl ethyl ketone (MEK) insoluble fraction reached about 80%.The 13CNMR spectra indicated that its microstructure sequence was isotacticrich polystyrene.The contents of mm triad and mmmm pentad were equal to 57% and 45%,respectively.The Tg of 100℃ and melting temperature at 211℃ were observed in DSC curves.The isotactic content of MEK soluble fraction was also higher than that of PS obtained by conventional anionic polymerization.The GPC results displayed an obvious difference between the theoretical molecular weight and experimental molecular weight.It also indicated a much broader polydispersity of the experimental sample.- 21
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发布时间：2021-03-19 - 摘要：A new series of diblock polystyrenebpoly(Dlactide) (PSbPDLA) were successfully synthesized with narrow molecular weight distribution and a PDLA block weight fraction fw of 0～0.61. By means of temperaturemodulated differential scanning calorimeter (TMDSC),DSC and polarized optical microscopy,thermal and crystallization kinetics of these diblock copolymers have been studied along with the semi-crystalline PDLA homopolymer.It was found that the increase in rigid amorphous polystyrene block led to remarked confinement effect on melting point,degree of crystallinity and crystallization kinetics for the semi-crystalline PDLA blocks.The cold crystallization temperature and crystal equilibrium melting temperature for the PDLA block chains were revealed to be 14℃ and 38℃ lower than those of PDLA homopolymers,respectively.It was also noted that the crystallization behavior and apparent crystal growth rate were observed to vary at a temperature near the glass transition temperature of PS block chains.In addition,POM results indicated the diblock PS-b-PDLA organized spherulites,and apparent crystal growth rates not only depended on isothermal crystallization temperature,but the PDLA blocks weight fraction.Taking the effect of crystallization of PDLA blocks into consideration,these evidences may be helpful for controlled fabrication of 3D mesoscopic structures by self-assembling diblock PS-b-PDLA.
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发布时间：2021-03-19 - 摘要：The updating process of interface plays an important role in the polymer reactive blending process,including the changes of interfacial area and phase morphology,and the material transportation.In this article,by using a typical thermodynamic incompatible blending system,polyolefin elastomer/polystyrene,the influence of different morphology (sea\|island structure and co-continuous structure) on the polymer reactive blending processes was investigated by means of rheology and morphology analyses.Rheological analysis suggests the additional contribution of formed block copolymer in the reactive blends,as well as the variation of relaxation process of droplets in sea\|island blend.The conversion in a typical blend is analyzed based on the change of interfacial relaxation time and droplet size by using the mean field theory.It is then suggested that phase morphology has a significant influence on the polymer reactive blending processes.Interfacial reactions happen more easily in blends with co\|continuous morphology due to their weak stability,while in the blends with the sea\|island morphology,the interface reaction process depends on the ease of interface deformation,and the blends system with small viscosity ratio favors interfacial reactions.
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发布时间：2021-03-19 - 摘要：A negatively charged PSt seed latex was first synthesized via batch emulsifierfree emulsion polymerization,and the PSt particles were then dispersed into the medium of ethanol and water,and γaminopropyltriethoxysilane (KH550) was added to modify the particle surface at 25℃ to prepare the positively charged and silylated PSt particles.Finally,the coreshell PSt/SiO2 composite microspheres were obtained by dropwise adding tetraethoxysilane (TEOS) into the above system under alkaline condition.Influences of KH550 amount on zeta potential of PSt seed latex,and influences of reaction time and EtOH/H2O ratio on the morphology of PSt/SiO2 composite microspheres were investigated.Results showed that zeta potential of PSt seed latex increased with increasing the KH550 amount,and reached its optimum value of 38 mV from -345 mV when the amount of KH550 was increased to 1/3 of PSt seed weight.In the preparation of coreshell PSt/SiO2 composite microspheres,the encapsulation ratio of SiO2 onto the modified PSt particles increased with the increasing reaction time,and maximum value of 979% achieved when the reaction time prolonged to 24 h;With the decrease of EtOH/H2O,the number of SiO2 nanoparticles absorbed onto the composite microspheres decreased,and the uniform coreshell PSt/SiO2 composite microspheres with the shell thickness about 35 nm were obtained in the medium with EtOH/H2O weight ratio of 60/285
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发布时间：2021-03-19 - 摘要：A side chain liquid crystalline (LC) polyacetylene with long spacers,namely,poly(11-{［(4′-heptoxy-4-biphenylyl)carbonyl］oxy}-1-undecyne) (PA9,7),with high trans configuration was synthesized and the phase structures and transition behaviors were studied using differential scanning calorimetry (DSC),one-and two-dimensional (1D and 2D) wideangle Xray diffraction (WAXD)and polarized light microscopy (PLM).The molecular packing was simulated by Materials Studio (Accelrys) and the energy was minimized using Smart Minimizer incorporated in the Discover Molecular Simulation Program.The long spacer of PA-9,7 decouples the side chain mesogen and the rigid polyacetylene backbone and results in the formation of smectic phases,but not the frustrated highly ordered smectic phase of its cousin with short spacer.DSC and 1D WAXD results showed that the sample possesses two LC phases.Based on structural results obtained from 2D WAXD experiments on oriented sample,the phase structures of PA9,7 were determined to be smectic B phase (SmB) below 70℃,smectic A phase (SmA) in the temperature ranges 70 ~ 118℃,and isotropic phase (Iso) higher than 118℃.For the SmB phase,the side chains can pack into the pseudo-long range order with hexagonal symmetry within the smectic layers.The LC phase transition of PA-9,7 follows the sequence of SmB-SmAIso.
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发布时间：2021-03-19 - 摘要：The introduction of phosphorus can effectively improve the flame retardancy,thermal stability,biocompatibility and other properties of polymers.The novel styrene derivant (MED) with phosphaphenanthrene sidegroup was first synthesized by means of twostep esterification of 2-(6-oxide-6H-dibenz1,2oxaphos-phorin-6-yl)- 1,4-dihydroxyphenylenes (ODOPB) as the center unit with 4-pentyloxybenzoic acid and 4ethenylbenzoic acid,respectively.The free-radical polymerization of MED initiated by AIBN was carried out for 12 h in THF solution.The yield of product (PED) is over 80%.Comparing with that of MED,the 1HNMR spectrum of PED demonstrated that the polymerization of MED is realized successfully.Due to the strong π-π stacking and polar interaction between phosphaphenanthrene-containing pendent groups,as well as the rigid mainchain of polystyrene,PED can easily form aggregation state in polar solvents,such as DMF and THF,as a result the molecular weights of PED are beyond the detection range of GPC.At the same time,the TGA results reveal the excellent thermal stability of MED and PED because the temperatures are 339℃ for MED and 345℃ for PED at the 5% weight loss,respectively.For the induction of mainchain on the ordered arrangement and the strong interaction between the side-groups,the intramolecular rotation of phosphaphenanthrene groups in PED is more difficult than that in MED.So that,the non-radiative deactivation is decreased and the fluorescence intensity of PED in the pure THF solution is remarkably enhanced.With the addition of water or n-hexane,the fluorescence intensity of PED is induced to decrease because of the disordered aggregation between chains.When the water content was over 70%,the complexes based on the hydrogen bond bridge among a water molecule and two phosphaphenanthrene groups enhanced the intramolecular rotation restriction of some phosphaphenanthrene groups.Therefore,new shoulder peak at 450 nm is shown and the PL intensity increases.Clearly,the light emission of PED is induced by aggregating formation; in other word,PED is aggregation-|induced emission(AIE)-active.When n-hexane as precipitant instead of water,the above-mentioned phenomenon is not shown in the absence of the formation of hydrogen-bonded complex structure.The fluorescence intensity continuously reduced with increasing of the content of n-hexane in the THF/n-hexane mixtures.The results allow us to design new materials with higher performance for chemo- and bio-detection applications.
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发布时间：2021-03-19 - 摘要：Colloidal spheres composed of two amphiphilic azo polymers were fabricated and characterized.The colloidal spheres were prepared from BP-AZ-CA and BP-AZ-NT through gradual hydrophobic aggregation in THF H2O solutions induced by increase in the water content.The relationship between the scattering light intensity and water content of the system was studied.The results show that during the aggregating progress,the more hydrophobic BP-AZ-NT tends to aggregate first,so the critical water content(CWC) of the system is determined by the more hydrophobic component.Because of the less hydrophobic molecules apt to aggregate later,so the outside layer of the colloidal spheres contains less hydrophobic BP-AZ-CA molecules.Upon irradiation of a linearly polarized Ar+ laser beam （488 nm，100 mW/cm2）,the hybrid colloidal spheres were elongated along the polarization of the laser beam.The results show that for the twocomponent colloidal spheres containing both BP-AZ-CA and BP-AZ-NT,the elongation rate of the colloidal spheres at first stage is similar to the colloidal spheres composed of BP-AZ-CA,but the final deformation degree is slightly smaller than that of BP-AZ-CA colloids.
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发布时间：2021-03-19
Research Article
- 摘要：A series of chalcone-containing copolymers with the solvent and temperature dual responsive fluorescence were synthesized by the radical copolymerization of N-isopropylacrylamide(NIPAM) and 4-methacryloyloxy4′-dimethylaminochalcone(DMAC) in THF solution using AIBN as initiator,and their structures were confirmed by FTIR,1H\|NMR and UV-Vis spectroscopy.The chalcone content in the copolymer was determined by UV-Vis absorbance method.The thermosensitivity of chalconecontaining copolymers and their solvent and temperature dual responsive fluorescence were investigated.The results show that the as-synthesized chalconecontaining copolymers are a kind of thermosensitive polymers with a lower critical solution temperature (LCST) and the LCST of the copolymer decreases with the increase of the chalcone content in the copolymer.With the increase of the solvent polarity,both the maximum absorption wavelength and the fluorescence emitting wavelength of the chalconecontaining copolymers red\|shifts,and the intensity of fluorescence first increases,then decreases,which exhibits solvent polarity sensitive fluorescence properties.Comparing the fluorescence of the copolymer aqueous solution at different temperatures,it is found that at high temperature the fluorescence of the copolymer has been enhanced,which endows the chalcone-containing copolymers with the reversible temperature “on/off” fluorescence properties.
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发布时间：2021-03-19 - 摘要：Lowpressure glow discharge of air plasma was used to increase the wettability of wood/PE composites in order to improve their adhesion properties.The changes in surface properties of the composites treated under plasma were studied by contact angle measurements,Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) analysis.Contact angle were measured at different exposure times for a series of test liquids,and the results showed that the contact angle decreased after being plasma treated under different exposure time,which meant that the surface wettability of the composites was improved significantly.The FTIR analysis results showed that polar groups such as hydroxyl,carbonyl and carboxyl were formed on the surface of the composites treated under plasma.And the generation of these polar groups was benefit of improving the wettability and adhesion capability of wood/PE composites.XPS analysis results indicated that the content of oxygen element in the composition of surface element for wood/PE composites increased after plasma treating,and it reached a balance in a short time,meanwhile a lot of carboxyl groups were formed.
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发布时间：2021-03-19 - 摘要：A poly(lactic acid)\|based block copolymer was synthesized in order to increase the cell ahesion of poly(lactic acid).Lys(Z)NCA was first synthesized from Nε-carbobenzyloxy-L-lysine and triphosgene in THF.Diblock copolymers aminoended poly(Nε-carbobonzyloxy-L-lysine)-b-poly(lactic acid) were synthesized in DMF in the condition that amino-ended PLA was used as initiator.Amphiphilic triblock copolymers poly(L-lactic acid)-b-poly(Nεcarbobonzyloxy-L-lysine)-b-poly(ethylene glycol) were synthesized in CHCl3 in the condition that amino-ended poly(lactic acid)-b-poly(Nε-carbobenzyloxy-L-lysine) was acylationed by carboxyl-terminal poly(ethylene glyco1).The block copolymers were characterized via IR(infrared spectroscopy),1H-NMR(nuclear magnetic resonance),GPC(gel permeation chromatography) and TEM(transmission electron micrographs).The results revealed that triblock copolymers with controlled Mn and narrow molecular weight distribution (Mw/Mn =1.07) were synthesized,the acylation reaction yield was more than 70%.Poly(ethylene glyco1) and Nε-carbobenzyloxy-L-lysine were introduced into the main chain of poly(lactic acid),and a kind of ideal bioabsorbable polymer materials were obtained.
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发布时间：2021-03-19 - 摘要：Poly(N-isopropylacrylamide) microgel with functional benzo-18-crown-6 group was synthesized by modifying a parent poly(Nisopropylacrylamidecoacrylic acid) microgel with 4′-aminobenzo18-crown-6 under EDC catalysis.The introduction of the functional groups was confirmed by IR and NMR.The resultant microgel is still thermosensitive,but the volume phase transition temperature shifts from 30℃ to 42℃.The swelling degree of the microgels increases too,indicating the 4′-acrylamidobenzo-18-crown-6 monomer acts as an hydrophilic one.The effects of Na+ and Pb 2+ on the microgel size were studied by dynamic light scattering.When ionic strength is not controlled,the microgel size decreases with increasing ［NaCl］,but first decreases followed by increasing with increasing ［Pb(NO3)2］.When ionic strength is kept constant,increasing ［Na+］ has little effect on microgel size.In contrast,microgel size expands significantly with increasing ［Pb2+ ］.In this case,the effect of ionic strength was avoided.Because of its high affinity to 18-crown-6,the binding of Pb2+ with crown ether further increases its hydrophilicity,so the microgels swell to a larger extent.However the binding constant between Na+ and 18-crown-6 is small,therefore it induces little swelling of the microgel particles.The light scattering results also show a narrow size distribution of the microgels.The monodisperse,lead-sensitive microgel may find application for the fabrication of new lead sensors.
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发布时间：2021-03-19 - 摘要：The hydrophobic association hydrogels (HA gels) were synthesized through micellar copolymerization of acrylic acid (AA) and a small amount of octadecyl methacrylate (OMA) in solution containing sodium dodecyl sulphate (SDS).The associated micelles consisting of surfactants and hydrophobes acted as physical cross-linking points in the network structure of HA gels.The mechanical properties of HA gels were measured by one-way tensile experiments,and the results confirmed the high toughness of asobtained hydrogels.The mechanical properties were associated with the effective network chain density and the effective cross-linking point contents.With increasing the content of hydrophilic or hydrophobic monomer in the HA gels,the strength of HA gels all increased while the elongation at break all decreased.Furthermore,the swelling behavior of HA gels in aqueous solutions at different pH values was also investigated.It was found that the HA gels possessed unusual swelling behavior.The swelling process could be divided into three stages:namely,the gel erosion stage,swelling equilibrium stage and gel disruption stage.At strong acidity,the swelling of gel was restrained,and the gel disruption stage did not appear.At strong alkaline condition,the swelling of gels was accelerated so that the swelling equilibrium stage was overpassed.Last,the salt effect restrained the swelling of HA gels,however,in SDS aqueous solutions,the SDS would drag the hydrophobically modified polymers into solution,then new association network was formed,and thus the solution was thickened.The hydrophobic association hydrogels (HA gels) were synthesized through micellar copolymerization of acrylic acid (AA) and a small amount of octadecyl methacrylate (OMA) in solution containing sodium dodecyl sulphate (SDS).The associated micelles consisting of surfactants and hydrophobes acted as physical cross-linking points in the network structure of HA gels.The mechanical properties of HA gels were measured by one-way tensile experiments,and the results confirmed the high toughness of asobtained hydrogels.The mechanical properties were associated with the effective network chain density and the effective cross-linking point contents.With increasing the content of hydrophilic or hydrophobic monomer in the HA gels,the strength of HA gels all increased while the elongation at break all decreased.Furthermore,the swelling behavior of HA gels in aqueous solutions at different pH values was also investigated.It was found that the HA gels possessed unusual swelling behavior.The swelling process could be divided into three stages:namely,the gel erosion stage,swelling equilibrium stage and gel disruption stage.At strong acidity,the swelling of gel was restrained,and the gel disruption stage did not appear.At strong alkaline condition,the swelling of gels was accelerated so that the swelling equilibrium stage was overpassed.Last,the salt effect restrained the swelling of HA gels,however,in SDS aqueous solutions,the SDS would drag the hydrophobically modified polymers into solution,then new association network was formed,and thus the solution was thickened.
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发布时间：2021-03-19 - 摘要：A polystyrenebased polymeric diazonium salt (PS-DAS) was used to demonstrate that its ultrathin films could be prepared through a sequential growth manner.The films were prepared by dipping the substrates in the PSDAS solution,washing with deionized water,and drying repeatedly.The growing process of untrathin films was monitored by UV-Vis spectroscopy and ellipsometry.The surface morphology and wettability of the films were characterized by AFM and water contact angle measurements.Results showed that PS-DAS could form thin films through uniformly layer-by-layered growth manner by a repeated dipping-coating- drying process.The UV-Vis and ellipsometry results showed that the amount of PS-DAS adsorbed in each dipping cycle was almost the same.In the dipping-washing-drying cycles,the drying step after each deposition was critical for growth of the PS-DAS ultrathin film.After heating treatment,cross-linking occurred in the thin films.The water contact angle changed from 77° to 90.7° after heating,which indicated the decomposition of the diazonium functional groups.The solvent resistance of the PSDAS ultrathin films was also greatly enhanced by cross-linking.The observations are helpful for understanding the unique self-assembling properties of polymeric diazonium salt which could be used to prepare ultrathin films.
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发布时间：2021-03-19
Research Bulletin
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