最新刊期
卷 ， 期 10 ， 2008
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PREPARATION AND MISCRIBILITY STUDIES OF POLY(L-LACTIC ACID)/POLY(ASPARTIC ACID-co-LACTIC ACID)BLENDS
摘要：Blends of PLLA and PAL were prepared by solution-cast method using co-boiling reagents including chloroform and ethanol (93/7,V/V),and the co-boiling temperature was about 60℃,which could avoid the phase splitting of PLLA and PAL caused by different evaporate speed of the two solvents or polymer asynchronous precipitation.Thus,PLLA/PAL blends were obtained with uniform dispersion.The thermal properties and morphologies of the blends were studied,and the miscibility of PLLA and PAL was evaluated by DSC and POM.Each PLLA/PAL blend has a single Tg,and each testedTg is closed to the calculated one according to Fox theory.Thus,the blends have homogeneous amorphous phase,and PAL and amorphous region of PLLA are miscible.In the blends,PLLA’s Tm was reduced by adding into PAL,and the melting blends were thermodynamically stable systems.Amorphous PAL showed obvious effect on the thermal properties and crystallization behaviours of PLLA in the blends,which indicated PLLA and PAL were compatible.PLLA in the blends exhibited faulty spherulites,lower melting points and lower crystallinity.The growth of PLLA spherulites was varied from homogeneous coring to heterogeneous coring in the presence of PAL.POM micrographs showed that PAL was among the lamellar crystals of PLLA spherulites,and changed the PLLA crystal shape to faulty spherulites.PAL had the retardarce action on the crystallization speed of PLLA melt,and caused PLLA spherulites to become imperfect.Because of the chain entwisting and hydrogen bond forming,the interactions between PLLA and PAL chains are strong.Thus,PLLA and PAL are miscible and form the blends with miscible structures.When PAL content was less than 20%,the tensile strength and break elongation were higher than those of pure PLLA,and the blend of 10% PAL content showed the best tensile properties.- 26
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发布时间：2021-03-19 - 摘要：Poly(N,N-diethylacrylamide) (PDEA) is a temperature sensitive polymer,whose aqueous solution separates into two phases when the temperature excess the lower critical solution temperature (LCST),accompanying with the collapse of the chains.The purpose of this work was to distinguish the different explanations of the energy change during transition and to investigate the microscopic details of the PDEA-water interaction related to single-chain conformational changes occurring across the LCST.The molecular dynamics (MD) was used to simulate the aqueous solutions of thermoresponsive PDEA molecules with 50 units at 300 K and 310 K for the compact and extended chain conformations,and the number of hydrogen bonds (HB) in the solution was analyzed in more detail.The MD simulations were performed by using the Tinker program with the force field OPLS.The simulation system consisted of 6103 TIP3P water molecules surrounding one PDEA molecule.In order to maintain simulations within the canonical ensemble (NVT),the Berendsen thermostat was used.The integration step was set to be 1 fs,and coordinates were saved every 0.3 ps.The total simulation time including the equilibration and production run,in which statistical data were gathered,was 2000 ps,where the last 300 ps of each simulation was utilized as the production run period.After the simulation,the trajectory files can be analyzed as required.Analyses of trajectories show that the water molecules mainly contact with the nonpolar groups of PDEA.The average number of HB per water molecule varies with the distance of water to polymer in the PDEA aqueous solution.The water molecules form more hydrogen bonds and are in the more ordered structure in the first shell and the second shell around the polymer than those in the bulk water.When the polymer chain transfers from the extended conformation to the compact one,the number of water molecules in the first shell,especially the number of water molecules surrounding the nonpolar groups of PDEA,reduces accompanying with the decrease of the HB number in the solution.As a result,both the enthalpy and entropy of the solution increase.It supports the assumption that the energy change mainly comes from the alternation of the number of hydrogen bonds between water molecules in the first-shell.The selfdiffusion coefficients of polymer molecules and water molecules were also been discussed.The value of self-diffusion coefficient for water molecules surrounding the PDEA is smaller than that in the bulk water,and the value of self-diffusion coefficient for PDEA increases as the polymer chain is compacted.
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发布时间：2021-03-19 - 摘要：Two types of initiators,watersoluble(potassium persulphate,KPS) and oilsoluble(2,2′-azobisisobutylonitrile,AIBN) initiators,were applied to initiate the copolymerization of γ-methacryloxypropyltrimethoxysilane (MPS) and styrene (St) in miniemulsion mode.The influences of the nature of initiators on the kinetics including the hydrolysis of methoxysilyl groups and free radical copolymerization,the stability of latex particles and the microstructure of copolymer were investigated.The overall conversion was measured by gravimetry; the methanol content and individual monomer conversion during the process of reaction were followed by gas chromatogram; the size of minidroplets and latex particles were measured by DLS; the microstructure of copolymer was characterized by FTIR and 29Si solid state NMR,respectively.The interfaces of mini-droplets or latex particles were the main loci of hydrolysis reactions attested by the independence of hydrolysis rate of MPS on the nature of initiator which could determine the distribution of radicals between aqueous and oil phases.The hydrolysis rate increased with the increase of the MPS/St ratio because of the increase of the amount of MPS at the interface,but the final hydrolysis degree was independent on the MPS/St ratio for both systems initiated by AIBN and KPS as a result of the simultaneous increase of the amount of MPS at the interfaces and in the interior of droplets or latex particles.Compared to the system initiated by KPS,the higher final hydrolysis degree appeared in the system initiated by AIBN could be attributed to the lower reaction rate and longer reaction time.The kinetic behaviors of copolymerization of MPS and St and homopolymerization of St initiated by KPS showed in the completely different way,but in the similar way for the system initiated by the AIBN.This phenomenon could be ascribed to the different water solubility of monomers and the different origin of radicals of KPS and AIBN.The introduction of MPS accelerated the copolymerization rate especially in the initial stage due to its higher propagation constant and reactivity ratio than that of St.Besides the participation in the free radical copolymerization,MPS molecules underwent the hydrolysis and then condensation reactions concurrently.Consequently,the formation of the hydrogen bonding among the resultants of hydrolysis,Si—OH,increased the rigidity of the interface and retarded the polymerization rate.In contrast to the system initiated by KPS,the latex particles of system initiated by AIBN were more stable,and in the system with 1:4 ratio of MPS to St initiated by AIBN,the ratio of Np andNd was 0.97,but was only 0.55 in the system with the same ratio initiated by KPS.The results of FTIR and solid-state 29SiNMR showed that un-condensed silicone species dominated in the final product in the system with 1∶1 ratio of MPS to St initiated by KPS,and MPS molecules were incorporated in the copolymer via free radical (co)polymerization.We reported that a small part of Si—OH condensed in the system initiated by AIBN before.This could be attributed to the fast incorporation of Si—OH into the polymer chains which confined the mobility of Si—OH and reduced the possibility of condensation reaction as a result of the fast copolymerization rate in the system initiated by KPS.
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发布时间：2021-03-19 - 摘要：Poly(L-lactide-co-ε-caprolactone) P(LLA-co-CL) copolymers with various L-lactide/ε-caprolactone(L-LA/ε-CL) mole ratios were prepared by the ring opening copolymerization of L-LA andε-CL using nontoxic magnesium octoate as a catalyst in bulk.The time-conversion curves of L-LA and ε-CL copolymerization were recorded by1HNMR.The results showed significantly more rapid polymerization of LLA relative to ε-CL.The carbonyl carbon signals in 13C-NMR are most sensitive to the sequence distributions of the lactidyl and caproyl units and used for calculating their average block length (LLLe and LCe).Two modes of transesterification occurred during the copolymerization process and played an important role in the redistribution of comonomer sequences.With polymerization progress,LLLe decreased sharply andLCe increased at first and then decreased gradually,as a result,the run number (R) increased gradually and the extent of randomness enhanced.The CLC sequence formed by the second mode of transesterification was observed at the end of reaction.Then,the reactivity ratios of L-LA and ε-CL were measured to berLA=23 and rCL=0.22,respectively,using the FinemanRoss method.The results(rLA1 and rCL 1) imply that Llactide monomer added preferentially into the copolymer chain end in the first step of the reaction,resulting in the formation of long blocks of lactidyl unit in the polymer chain.The copolymer composition has a profound influence on the values ofLLLe and LCe.Both LLLe and LCe increased as the relative proportions of their respective monomers increased.The transesterification coefficient of the second mode of lactidyl units(TⅡ［CLC］) increased as the feed mole fraction of ε-CL increased.In terms of the overall feed compositions,the LLLr values calculated from the reactivity ratio exceeded the LLLe values determined from the product; however,the LCr values were identical or shorter than the LCe values.Therefore,the repeat unit sequence distribution of the copolymers was varied more or less toward a random sequence distribution by variation in the comonomer feed ratio and reaction time.The thermal properties and crystallization of the copolymers were investigated by DSC and XRD.The results showed that a close relationship between copolymer crystallinity and the length of the copolymer sequences.All copolymers of L-LA and ε-CL exhibited a single Tgsdetermined from the second heating scan.The experimental Tgswere in agreement with the calculated Tgsvalues from Fox equation.It can be concluded that the copolymers are random,or comprise a mixture of compatible block copolymers.
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发布时间：2021-03-19 - 摘要：A surface active macromonomer of nonylphenol polyoxyethylene ether maleate (OPMA) was prepared with nonylphenol polyoxyethylene ether (OP-10) and maleic anhydride at 95～100℃.Copolymer surfactants of acrylamide (AM) and OPMA were synthesized in aqueous solutions with potassium persulfate (K2S2O8) and sodium bisulfite (NaHSO3) as initiators.The effects of the amount of initiator,OPMA mole fraction in total monomer,total monomer concentration and reaction temperature on intrinsic viscosity and the degree of anion (DA) of copolymers were investigated.The structure and composition of the copolymers were characterized by FTIR spectroscopy,UV spectroscopy,fluorescence emission spectroscopy and conductometric titration.Surface tension and interface tension between kerosene and copolymer aqueous solutions were measured by an optical contact angle measuring device.The experiment results indicated that the polymer of PAM incorporated by OPMA segments exhibited good thickening ability and surface activity due to the strong surface active nonylphenol polyoxyethylene ether groups.The results also showed that the intrinsic viscosity of copolymers reached a maximum value of 764.31 mL/g and DA of copolymer 5.6% when the reaction took 6 h under 35℃,0.06 wt% initiator concentration,0.02 OPMA mole fraction in total monomer and 16 wt% total monomer concentration.The surface tension and interface tension between kerosene and 1.5 g/L copolymer aqueous solution were 53.94 mN/m and 5.41 mN/m,respectively when DA of copolymers was between 2% and 4%.In a word,the intrinsic viscosity and DA of copolymers were strongly influenced by the reaction conditions and the surface activity of copolymers first decreased and then increased with increasing its DA.These copolymers with good thickening ability and surface activity could be used in enhanced oil recovery.
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发布时间：2021-03-19 - 摘要：Poly(arylene imino ether ketone) containing isopropylidene group (pr-PIEK) was synthesized by the condensation polymerization of 1,4-bis-(4-bromobenzoyl)benzene and 2,2-bis［4-(4-aminophenoxy)-phenyl］-propane via Palladiumcatalyzed aryl amination reaction with high molecular weight,Mn=5.15×104,Mw=1.26×105.The catalyst was tris(dibenzylideneacetone)dipalladium,and the catalyst ligand was BINAP.The monomers,1,4-bis-(4-bromobenzoyl)benzene was synthesized by Friedel Crafts benzoylation reaction,and 2,2-bis［4-(4-aminophenoxy)phenyl］propane was obtained via two steps.The structure of pr-PIEK was characterized by means of FT-IR,1H-NMR spectroscopy and elemental analysis,and the testing results showed a good agreement with the proposed structure.XRD,DSC and TG measurements show that pr-PIEK possess amorphous nature,good thermal stability with high decomposition temperatures (TD＞450℃),mechanical properties (tensile intensity=72.76 MPa,tensile modulus=1013.63 MPa,rupture tensibility=10.32%) and good solubility,pr-PIEK can be dissolved in common organic solvent CHCl3 at room temperature and dissolved in acetone at 50℃.
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发布时间：2021-03-19 - 摘要：Three conjugated copolymers containing different length of oligo(p-phenylene ethynylene) moieties (OPE) connecting at the bay position of N,N′-dioctylperylene-3,4:9,10-tetracarboxylic acid bisimide were designed and synthesized.The three OPE monomers were prepared according to a stepwise synthesis method.This method involves two sets of reaction conditions:desilylation and Pd/Cu-catalyzed coupling.In every two steps,2,5-dihexyloxy-4-(trimethylsilyl)ethynyl］iodobenzene was coupled with the diethynyl compounds which were desilylated from the di(trimethylsilyl)ethynyl compounds.Through this approach,undesired oligomerization was avoided and OPE monomer,trimer,pentamer were readily prepared in high purity.The bromination of perylene bisanhydride was carried out under reaction condition with a more than two-fold of bromine in 98% sulfuric acid.After imidization by n-octylamine with acetic acid as catalyst in NMP,the resultant compound was soluble in dichloromethane,which facilitated its purification.The coupling polymerization was performed by a standard Sonagashira reaction between the acetylene-terminated OPE monomers and perylene monomer,leading to the final three alternative copolymers (P1,P2,P3).After polymerization reaction has been finished,all polymers dissolved in chloroform and then reprecipitated in methanol for three times,followed by Soxhlet extraction with acetone for 48 h to remove residual catalyst and monomers.The structures of the three polymers were characterized by IR,Elementary analysis and GPC.P1 has limited solubility in common solvents such as THF,dichloromethane,toluene,etc,due to the high rigidity of the backbone as well as the high content of perylene.But the solubility of P2 and P3 was improved dramatically.The photophysical characteristics of the polymers were investigated by UV-Vis and PL spectra in solution.In UV-Vis,the absorptions of perylene in polymers show a large red-shift (nearly 170 nm) compared to that of the perylene monomer,indicating a strong interaction between electron donor and acceptor on the ground state.Together with a non-interfered conjugated backbone,all polymers absorb from 350 to 900 nm which makes them promising in photovoltaic applications.In PL experiments,when exciting the perylene part,a complete fluorescent quenching was observed in all three polymers,which can be attributed to the electron transfer process between the electron donor and acceptor induced by excitation of the electron acceptor segment to a charge separated state.When exciting the OPE unit in each polymer,only the emission from the OPE chromorphore was observed in all three polymers.Cyclic voltammetry (CV) was used to assess the electrochemical behavior of the polymers.All three polymers show a reversible reduction wave,an irreversible wave in the more negative field and an irreversible oxidation wave.The first reversible reduction wave comes from the n-doping of perylene unit in polymers.From P1 to P3,the onset potential of first reduction wave decreases,which is in accordance with the p-doping degree increasing in each polymer.At the oxidation side,the onset potential of oxidation goes to the opposite way that is increasing from P1 to P3.By changing the amount of electron donating or accepting content in the polymers,the electronic properties of the corresponding polymers can be manipulated,which can serve as a guide for new material design in the kind and facilitating the photovoltaic device fabrication.It is hoped that these new polymers would be a promising candidate used for polymeric solar cells.
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发布时间：2021-03-19 - 摘要：Regenerated silk fibroin solution and silica sol were mixed to produce the silk fibroin/silica composite materials.In order to probe if there is interaction between silk protein and silica,and further more,whether the interaction can improve the mechanical properties of composite materials,the structure and properties of the silk fibroin/silica composite material were studied by dynamic mechanical analysis (DMA) together with scanning electron microscopy (SEM) and Raman spectroscopy.The SEM results revealed the good compatibility between silk fibroin and silica in the composite.Nano-sized silica particles dispersed evenly in the continuous matrices of silk fibroin.Raman spectra of the composite materials indicated that the silk fibroin was dominated by β-sheet conformation.Comparing to the pure silk fibroin material,the composites showed better dynamic mechanical properties in the range of 15℃ to 55℃.When the content of silica reached 10%,the composite material appeared absolutely no dissipation in the temperature range around 40℃.Due to both the hydrogen bond and electrostatic interaction between SiO2 and silk fibroin,the silica particles’ interfusion among the chains of protein had a motiveimpeding influence on the protein chains.This influence together with the stable β-sheet conformation of silk fibroin matrices led the avoidance of modulus dissipation of the material.
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发布时间：2021-03-19 - 摘要：Silica/phenol resin hybrid material was prepared by a sol-gel process.Resole,tetraethoxysilare (TEOS),ethanol and water were mixed to form the precursor,the ratio being resole∶TEOS∶ethanol∶water = 4.1 g∶1.5 g∶20 mL∶2 mL.The precursor was hydrolysed for 24 h to obtain a hybrid material (organic/inorganic weight ratio 9∶1).Resole and the precursor was cured at 120℃,2 h concurrently,then,part of the hybrid material was postcured at 160℃,1 h.The three samples (phenol resole,hybrid material and post-cured hybrid material) were analysed by FTIR and evaluated in view of application as organic coatings.Because phenol resin is liable to change its color in service,the hybrid material is only applied as undercoat.The wavenumber shift of O—H stretch vibration,the ratio of peak width at half hight Δ1/2(O—H)/Δ1/2(C=C) and absorbance ratios were used to characterize the structure changes of the hibrid material.Under the same curing conditions (120℃,2 h), the O—H peak of the hybrid material shifts 49 cm-1 downward from that of resole,Hbond of the hybrid material (half hight 4.25) is stronger than that of resole (half hight 7.76),and there is more hydroxyl concentration in the hybrid material.As an undercoat,the hybrid material can have enough functional groups to react with those of the topcoat in order that the multiple coatings can cure without interface between undercoat and topcoat.Post cure (160℃,1 h) can greatly reduce the hydroxyl concentration of the hybrid material.Phenol resole has a weak absorbance peak at 1070 cm-1 (A1070/A1612=0.81),the hybrid materials (A1067/A1612=1.87; postcured A1069/A1612=2.99) have two very strong absorbance peaks in the range of 1100～1065 cm-1,therefore,the hybrid materials have more ether bonds than resole, and post-cure can form more ether bonds.The absorbance ratio ［A］754/［A］1612 that expresses the substitution reaction of o-positions of the phenol rings increases from 4.25 of resole to 7.76 of the hybrid material,which means the substitution reaction of o-positions in the hybrid material is much more remarkabe than that in resole.The ［A］818/［A］1612 that expresses the substitution reaction of p-positions increases from 0.32 of the hybrid material to 0.51 of postcured hybrid material,but ［A］754/［A］1612 increases unremarkably,which means the substitution reaction of p-positions in the hybrid material during postcure is predominant, and the substitution reaction of o-positions is negligible.The ratio A1646/A1612 of phenol resin is 0.53, and that of the post-cured hybrid material is 0.54,which means the postcured hybrid material gets the same oxidation degree as the phenol resin.The post-cured hybrid material does not have free phenols, consequently,the post-cured hybrid material is more environment-friendly than resole.
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发布时间：2021-03-19 - 摘要：A new type of nucleating agent (NA),compound nucleating agent made of ultra-fine rubber particles and organic phosphate,was applied to modify polypropylene (PP) resin.It is found that the new NA is a high efficiency nucleating agent.A small amount of organic phosphate NA can increase the crystallization rate and crystallization temperature of PP obviously. For example，a PP with crystallization temperature of 118.5℃ may have a crystallization temperature raised up to 125.6℃ while it is modified with 0.1% of this new NA containing only 0.02% organic phosphate NA.It is impossible to reach so high crystallization temperature if we use so small amount of pure organic phosphate NA.The morphology study showed that ultra-fine rubber particles acted as carriers of organic phosphate NA.The organic phosphate NA in compound NA could disperse better with the rubber particle dispersion in the PP matrix.Good dispersion of organic phosphate NA resulted in the high nucleating efficiency of new NA;therefore,PP modified with this new NA had high crystallization rate,high crystallization temperature and good mechanical properties while only a small amount of organic phosphate NA was used.
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发布时间：2021-03-19 - 摘要：A bulk heterojunction photovoltaic cell in which an isomeric mixture of fullerene derivatives,PC［70］BM is used as an electron acceptor in combination with poly(2-methoxy-5(2′-ethylhexyloxy)-1,4-phenylene vinylene) (MEH-PPV) as an electron donor has been reported.PC［70］BM is the higher fullerene analogue of PC［60］BM,and displays improved light absorption in the visible region.It is found out when this material is used instead of PC［60］BM in a photovoltaic cell with MEHPPV as donor,a value of 6.07 mA/cm2 current density for the PC［70］BM∶MEHPPV devices means an increase of over 40% with respect to an optimized PC［60］BM∶MEHPPV cell.The opencircuit voltage Voc of 0.85 V and a fill factor (FF) of 0.53 for the PC［70］BM∶MDMO-PPV devices resulted in an overall power-conversion efficiency of 3.42%,measured under AM1.5G,solar simulater (80 mW/cm2).The influence of different solvents used for spincasting of active layer on device performance was studied.The results showed that 1,2-dichlorobenzene was a best solvent for PC［70］BM/MEH-PPV system.The mechanism of the solvent influence on the device performance was analyzed by light and dark I-Vcurve,AFM,and reasonable explanations were given.Morphology studies on the blend films indicated that excellent miscibility between polymer and PC［70］BM favored exciton separation.Because the exciton diffusion length in organic materials is typically small,the intimate mixture favors exciton separation and therefore higher photocurrent.
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发布时间：2021-03-19 - 摘要：A novel fluorene-phenylene (FP) based cross-conjugated copolymer with donor-acceptor (D-A) architecture was synthesized by palladium-catalyzed Suzuki coupling reaction.In sample P1,the dibutylamino was introduced into the side chain,used as electron donor and ion receptor; the 2,1,3-benzothiadiazole was incorporated into the backbone and served as electron acceptor.For comparison, sample P2 without 2,1,3-benzothiadiazole moieties was also prepared.The chemical structure of P1 and P2 was confirmed by 1H-NMR,IR,elemental analysis and GPC.Cyclic voltammetry (CV) was used to assess the electrochemical behavior of the polymers.The HOMO levels of the P1 and P2 estimated from CV were -4.87 eV and -4.86 eV, respectively; the LUMO levels of P1 and P2 were -2.47 eV and -2.09 eV, respectively,that were consistent with the energy levels calculated by B3LYP/6.31G method.The results indicated that the manipulation of the energy levels of the HOMO and LUMO can also be achieved by the incorporation of donor-acceptor (D-A) moieties within cross-conjugated polymer systems.The presence of strong intramolecular charge transfer (ICT) in P1 was supported by the frontier orbital distribution calculated by AM1 method.Due to the ICT interactions,both the fluorescence emission of P1 and P2 exhibited strong solvatochromic effect，the fluorescence intensity of P1 decreased greatly with the increase the solvent’s polarity.The optical sensing properties of P1 and P2 in dichloromethane were investigated upon addition with Cu2+,Zn2+ and H+, respectively.P1 and P2 exhibited completely dissimilar optical response to cation,which can be ascribed to much stronger ICT effect in P1 Interestingly,by adding Cu2+,Zn2+ or H+ into P1 solution,the fluorescence intensity was amplified,which was descried as a “turn-on" effect.The dramatic result was attributed to a strong modulation of ICT interactions by complexation with cation.However,upon coordination with a small amount of Cu2+,the emission of P2 (470 nm) was quenched and redshifted to 512 nm; when the concentration of Cu2+was increased,the emission of P2 was blueshifted to 435 nm.These preliminary results showed that the FP based cross-conjugated polymers with D-A structure can be served as potential sensory materials with “turnon" property.
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发布时间：2021-03-19
Research Article
- 摘要：A novel biomimetic amphiphilic polymer,cholesterol-end-capped-poly(2-methacryloyloxyethyl phosphorylcholine) (CPMPC),was used as surfactant to achieve water soluble and biocompatible carbon nanotubes (CNTs).Crude CNTs were facilely dispersed in aqueous media by ultrasonication with the help of CPMPC,with cholesterol-end-capped PEG (CPEG) and lecithin as controls.The ability of the novel biomimetic amphiphile to solubilize and stabilize the CNTs was investigated by UV spectra.The solubility of CNTs in 1 mg/mL CPMPC and CPEG aqueous solutions was found to be 1.705 mg/mL and 1.468 mg/mL,respectively.The solubility of CNTs,in 0.8 mg/mL lecithin was,however,only 0.326 mg/mL.Furthermore,CPMPC coated CNTs precipitated quite slowly compared with CPEG coated CNTs,which indicated better stabilizing ability of CPMPC.Cell culture was used to evaluate the biocompatibility of the amphiphiles stabilized CNTs using MTT assay and cell morphology observation.While CPEG coated CNTs showed obviously detrimental effect on the growth of HUVEC304 cells,CPMPC coated CNTs did not exhibit obvious toxicity.The biocompatible CPMPC coated CNTs represent an excellent nano-object for potential biomedical applications.
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发布时间：2021-03-19 - 摘要：A hybrid double-hydrophilic block copolymer (DHBC) of PEG-b-PEI-SO3H with sulfonic groups was synthesized and investigated as a modifying additive for CaCO3 crystallization.The DHBC was well characterized by FTIR.Primary investigations indicated that this hybrid double hydrophilic block copolymer (DHBC) possessed strong modifying ability for both polymorphism and morphologies of inorganic crystals due to the especial structure with sulfonic groups.The crystal morphologies were investigated by SEM and TEM.The SEM and TEM results indicated that pure hollow round ring calcite was obtained after 1 day,while mussel-like and sphericallike calcium carbonates were produced after 3 or 5 days.When the reaction time was 7 days,almost pure spherical particles were obtained.The crystal phases were fully characterized with FTIR,XRD.The XRD results indicated that the calcium carbonate obtained after 1 day was calcite,and not only calcite but also vaterite was formed after 3 or 5 days,pure vaterite was produced after 7 days.These results were accordant with the FTIR measurement.When the reaction time was 1 day,the peaks at 875 cm-1 and 712 cm-1 indicated the calcium carbonate obtained was calcite.With prolonging of reaction time from 1 day to 3 or 5 days,the peaks at 875 cm-1,745 cm-1 and 712 cm-1 identified the calcite as well as vaterite crystals.While the 875 cm-1 and 745 cm-1 peaks appeared after 7 days, but the peak at 712 cm-1disappeared,which showed that the pure vaterite was produced.
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发布时间：2021-03-19 - 摘要：A series of high molecular weight alternative and random poly(aryl ether ketone ketone) copolymers were prepared by low-temperature solution poly-condensation,with 1,4-bis(4-phenoxybenzoyl)benzene (p-EKKE),1,3bis(4-phenoxybenzoyl)benzene (m-EKKE),diphenyl ether (DPE) and terephthaloyl chloride (TPC) or isophthaloyl chloride (IPC), respectively.The inherent viscosities (ηnh) of resulting copolymers were in the range of 0.63～1.08 dL/g.The chemical structure of p-EKKE,m-EKKE and PEKKs were confirmed by FT-IR.The thermal properties of copolymers were obtained by DSC and TG. The DSC results indicated that the melt temperature (Tm) and the glass transition temperature (Tg) decreased with increasing the amount of meta-phenylene substituted in the main chain. The TG results showed that the copolymers had excellent thermooxidative stability,being stable above 530℃,which was affected slightly by the amount of meta-phenylene substituted in the main chain.The alternative copolymer b-PEKK has better order and higher crystallinity than random copolymers.WAXD showed that copolymer p-PEKK and its model compound had the same crystallization diffraction spectra corresponding to a rhombic system.While the morphology of the copolymer i-PEKK and the corresponding model compound showed needle crystals,which belonged to an anorthic system.i-PEKK was difficult to crystallize again in the course of melting,and it was in an amorphous state.
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发布时间：2021-03-19 - 摘要：To obtain well-defined structures of a β-cyclodextrin based monomer and its hyperbranched polymer,an AB2 type monomer carrying Si—H and —CHCH2 groups was first synthesized via modification of C-2 and C-6 hydroxyl groups in β-cyclodextrin,respectively.And then,the watersoluble hyperbranched polymer was prepared via hydrosilylation using N,N-dimethylformamide as the solvent and H2PtCl6 as the catalyst at 100℃.The molecular structures for both monomer and polymer were characterized by 1H-NMR,13C-NMR,MALDI-TOF MS and elemental analysis.It was found that the actual molecular structures for both monomer and polymer were identical with the designed structures,and there also existed α-hydrosilylation and β-hydrosilylation during polymerization,as a result,the hyperbranched polymer possesses a large amount of functional vinyl bonds around its end chains.The polymer synthesized is soluble in tetrahydrofuran slightly and insoluble in nonpolar solvents such as hexane.The molecular weight,molecular weight distribution and intrinsic viscosity of the polymer were measured as 36690,1.887 and 15.8 mL/g,respectively by using size exclusion chromatography/multi-angle laser light scattering (SEC/MALLS) instrument.Due to two different cavities which are from β-cyclodextrin and the hyperbranched polymer,a possible novel spuramolecular system which may capsulize two more different molecules in a single polymer can be constructed.
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发布时间：2021-03-19
Research Bulletin
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