ABA triblock copolymers with two crystallizable blocks

Triblock copolymers of the ABA type were synthesized in which the A block is poly(ethylene oxide) (PEO), having molecular weight of 1000 or 2000, and the B block is poly(dimethylsiloxane) (PDMS), having molecular weight of about 8000 or 10,000. When the triblock copolymer was cooled from the melt, the PEO block crystallized at around room temperature. Upon further cooling to liquid nitrogen temperature and reheating, the crystallization of the PDMS middle block took place at around ?90°C. The melting temperatures and degrees of crystallinity of the PEO blocks in the copolymers were depressed from their respective pure state values. On the other hand, the melting points of the PDMS middle blocks in the copolymers were the same as the pure state values; furthermore, the degrees of crystallinity were unexpectedly much higher. © 1993 John Wiley & Sons, Inc.     

Synthesis and characterization of polyoxazoline-polysulfone triblock copolymers

Amphiphilic triblock poly(2-ethyl-2-oxazoline-b-sulfone-b-2-ethyl-2-oxazoline) (PEOX-b-PSF-b-PEOX) and poly(2-ethyl-2-oxazoline-co-ethyleneimine-b-sulfone-b-2-ethyl-2-oxazoline-co-ethyleneimine) (PEOXcoPEI-b-PSF-b-PEOXcoPEI) copolymers were synthesized for potential use as water purification membranes. Poly(arylene ether sulfone) (polysulfone) oligomers of controlled molecular weight were prepared by nucleophilic step polymerization of 4,4′-dichlorodiphenyl sulfone with a molar excess of bisphenol-A. The phenolate endgroups were then reacted with ethylene carbonate to afford telechelic aliphatic hydroxyethyl groups. These were tosylated to produce macroinitiators for ring-opening cationic polymerization of 2-ethyl-2-oxazoline. Subsequently, the pendent amides on the hydrophilic PEOX blocks were also hydrolyzed to generate positively charged PEOXcoPEI-b-PSF-b-PEOXcoPEI copolymers. Compositions with high polysulfone compositions relative to the hydrophilic blocks were of particular interest because they maintained good mechanical integrity in water. Water uptake at room temperature increased up to 18 wt% for copolymers with 22 wt% of the hydrophilic components. Solid-state thermal properties suggested some phase mixing of the components in the PEOX-b-PSF-b-PEOX copolymers but better phase separation of the blocks in the partially hydrolyzed PEOXcoPEO-b-PSF-b-PEOXcoPEI materials.     

Synthesis and characterization of nylon-polyisobutylenenylon triblock copolymers

Nylon-6-polyisobutylene-nylon-6 triblock copolymers have been synthesized by converting telechelic polyisobutylene diols to , -diisocyanate polyisobutylenes and using these macroactivators, in conjunction with strong base, to induce the subsequent anionic polymerization of -caprolactam. Pure block copolymer was obtained by suitable sequential extraction. Products were characterized by composition, molecular weight and DSC.     

氯化顺丁橡胶的合成及基本性能

在300t/a氯化顺丁橡胶装置上利用顺丁橡胶和氯化剂合成出氯化顺(CBR）以及不同反应时间，碱胶比和碱浓度对氯化反应的影响，研究了CBR胶液的流变特性和CBR的基本性能。     

Synthesis of water-soluble ABC triblock copolymers containing polypeptide segments

This article describes a facile approach for the synthesis of water-soluble ABC triblock copolymers through a combination of atom transfer radical polymerization (ATRP) and click reactions. The bromine-terminated MPEO–PtBA–Br precursor was first prepared by ATRP, and converted into the azido-terminated precursor MPEO–PtBA–N₃ by a simple nucleophilic substitution. Then, MPEO–PtBA–PzLLys triblock copolymers were synthesized via the click reaction of MPEO–PtBA–N₃ and the propargyl-terminated poly(N^ε-carbobenzoxy-l-lysine)s (PzLLys). The water-soluble MPEO–PAA–PLLys ABC triblock copolymers were obtained from the hydrolysis process. The structures of these block copolymers were characterized by NMR, IR and GPC.     

以稀土催化剂合成顺式-1,4-聚丁二烯-反式-1,4-聚丁二烯嵌段共聚物及其表征

以稀土催化剂合成顺式-1,4-聚丁二烯-反式-1,4-聚丁二烯嵌段共聚物及其表征郑文洁1,2,王凤1,2,张贺新1,张春雨1,白晨曦1,胡雁鸣1,张学全1(1.中国科学院长春应用化学研究所,合成橡胶重点实验室,长春130022;2.中国科学院大学,北京100039)利用异丙氧基钕/二异丁基氢化铝/二氯二甲基硅烷的活性聚合特征,首先合成窄分子量分布、顺式-1,4-结构为主的聚丁二烯,然后在聚合体系中加入正丁基镁和丁二烯单体,通过改变催化剂的立体选择性,制备了含有顺式-1,4-聚丁二烯与反式-1,4-聚丁二烯的两嵌段共聚物,并通过凝胶渗透色谱、核磁共振碳谱和差示扫描量热法对产物进行了表征。结果表明,嵌段共聚物的反式-1,4-结构摩尔分数较第1阶段聚合物明显提高(从29.4%增加到46.4%),且该聚合物具有顺式-1,4-聚丁二烯的玻璃化转变温度(-104.4℃)和反式-1,4-聚丁二烯的熔点(38.3℃和47.2℃)。     

Synthesis and characterization of stereotriblock polybutadiene containing crystallizable high trans-1,4-polybutadiene block by barium salt of di(ethylene glycol) ethylether/triisobutylaluminium/dilithium

A series of high trans-1,4-low-cis-1,4-high trans-1,4-stereotriblock polybutadienes (HTPB-b-LCPB-b-HTPBs) were synthesized through a sequential anionic polymerization of butadiene (Bd) initiated by barium salt of di(ethylene glycol) ethylether/triisobutylaluminium/dilithium (BaDEGEE/TIBA/DLi). The polymers consisted of elastic low-cis-1,4-polybutadiene (LCPB) chemically bonded with crystallizable high trans-1,4-polybutadiene (HTPB). The block ratios (HTPB:LCPB:HTPB) were designed at 25:50:25 (molar ratio) and finally determined by SEC. The microstructures and sequences of the specimens were investigated by FTIR and NMR. The resultant HTPB-b-LCPB-b-HTPBs consisted of LCPB block with 52.5% trans-1,4 content and HTPB block with 55.9–85.8% trans-1,4 content. According to differential scanning calorimetry (DSC), HTPB-b-LCPB-b-HTPB showed a significant cold crystallization which was discussed in terms of entanglement concept. The cold crystallization temperature (T_cc) decreased whereas the melting temperature (T_m) increased with the increasing trans-1,4 content of HTPB block.     

Synthesis and properties of triblock copolymers containing PDMS via AGET ATRP

The bromo-terminated macroinitiator was prepared by direct addition reaction of difunctional poly(dimethylsiloxane) (PDMS) containing methyl methacrylate end groups with hydrobromic acid in acetic acid under mild conditions, and well-defined triblock copolymers of poly(methyl methacrylate-b-dimethylsiloxane-b-methyl methacrylate) (MMA-b-DMS-b-MMA) were synthesized via activators generated by election transfer atom transfer radical polymerization (AGET ATRP). The gel permeation chromatography data obtained verified the polymerization and showed the well controlling of the reaction. FTIR and ¹H NMR measured the structure of the macroinitiator and copolymers. The contact angle measurement indicated that the water contact angles decreased gradually with the increasing of PMMA block content. The self-assembly behaviors of the triblock polymer were studied by transmission electron micrograph, scanning electron microscopy, and dynamic light scattering measurement. The results indicated that the polymers could self-assemble into various complex morphologies in different solvents and the morphologies depended on the properties of solvents. The possible molecular packing models for self-assembly behaviors of the ABA triblock polymers were proposed.     

以三亚甲基碳酸酯和丙交酯为单体的三嵌段共聚物的合成和表征

以1,6-己二醇为引发剂,辛酸亚锡为催化剂,通过开环聚合制备了PLLA-b-PTMC-b-PLLA和PDLA-b-PTMC-b-PDLA两种三嵌段共聚物,采用核磁共振和红外光谱谱图对产物进行了验证表征,并使用DSC和TGA对共聚物的热力学性能进行了测试。结果表明,通过控制单体与引发剂的比例可以分别获得不同分子量和分子量分布的三嵌段聚合物。在DSC曲线上,PLA-b-PTMC-b-PLA三嵌段共聚物表现出两个玻璃化温度,熔融峰的高度与PLA部分的含量呈正相关,而当PTMC含量占绝大部分时,该熔融峰变得不明显。     

Strain-induced crystallization of cis-1,4-polybutadiene containing dispersed 1,2-polybutadiene crystalline particles

Some grades of cis-1,4-polybutadiene contain dispersed crystalline particles made up of a block copolymer having amorphous cis-1,4- and crystalline 1,2 blocks. The particles are known to enhance the strain-induced crystallization of cis-1,4 matrix rubber. The deformational behavior was examined by dynamic shear measurements at small deformation and tensile stress–strain measurements at large deformation. In the shear measurements (linear behavior), the temperature dependence of the shift factor in the time-temperature superposition has been evaluated. The higher temperature dependence was observed for the lower crystalline particle content and higher degree of branching of the matrix rubber. The presence of the crystalline particles resulted in the viscosity enhancement like that expected from the dispersed particles. In the tensile measurements (non-linear behavior), the rubbers showed strain softening. The higher degree of strain softening was observed for the higher amount of the crystalline particles and lower degree of branching. The strain softening is a result of the crystalline particles facilitating the elongation. Because these particles posses the branches which are cis-1,4 chains of the block copolymer, the branches are lubricating the system during the stretching. The length of the branches must be short enough so as to produce no significant entanglement constraint. This observation is in accord with the previous one that a relatively long branch gives strain hardening, whereas a relatively short branch gives strain softening. The strain softening was found to enhance the strain-induced crystallization. This conclusion is opposite to what one might expect from the entanglement constraints by the long branches, forcing the orientation of the chains, and thus enhancing the strain-induced crystallization. © 1996 John Wiley & Sons, Inc.     

Synthesis and characterization of new biodegradable comb‐dendritic triblock copolymers

A series of well‐defined dumbbell‐shaped triblock copolymers consisting of linear poly(ethylene glycol) (PEG) and comb‐like poly(ε‐caprolactone) (PCL) with varied PCL arm lengths have been synthesized via the sequential preparation of different generation terminal dendronized PEG and ring‐opening polymerization of ε‐caprolactone. The copolymers were characterized using Fourier transform infrared, ¹H NMR and ¹³C NMR spectroscopy and gel permeation chromatography. Differential scanning calorimetry was performed to measure the glass transition temperature, melting point and degree of crystallinity and the PEG segment and PCL segment crystallization temperatures. The crystallization of the copolymers was also studied using X‐ray diffraction. The dumbbell‐shaped copolymers were further used to construct microspheres using a double emulsion method. Scanning electron microscopy and dynamic light scattering results showed the size of the microspheres was about 2 to 4 µm and the size distribution was quite narrow. Copyright © 2012 Society of Chemical Industry     

Toughened polystyrene containing high cis-1,4-polybutadiene rubber

High cis -1,4 -polybutadiene has been used to prepare toughened polystyrene in an attempt to improve its low temperature impact properties. A range of physical and mechanical properties was obtained by keeping the amount of rubber and the polymerization conditions constant, and varying the rate of agitation in a purpose -built reactor system. Although a good balance of tensile and impact properties is obtained at room temperature, the rubber partially crystallizes when the polyblends are cooled to below ?40°C. This should decrease the efficiency of rubber particles to create and terminate crazes. However, it is significant that the developed crystallinity decreases with the rubber phase volume, and is suppressed almost completely at about 21% rubber phase volume (RPV). The factors influencing the RPV are discussed, and a study of the phase inversion with three different types of rubber shows that its duration depends on the viscosity of the styrene/rubber system.     

Semifluorinated ABA triblock copolymers: Synthesis,characterization, and amphiphilic properties

In this study a series of novel semifluorinated ABA triblock copolymers with different fluorinated segment lengths and different fluorocarbon side‐chain structures were synthesized via atom transfer radical polymerization (ATRP) and macroinitiator techniques. The macroinitiator, telechelic bromine terminated polystyrene, was obtained from bulk ATRP of styrene with α,α′‐dibromo‐p‐xylene as the initiator and cuprous bromide/α,α′‐bispyridine complex as the catalyst. The polymerization reactions of 2‐[(perfluorononenyl)oxy] ethyl methacrylate and ethylene glycol monomethacrylate monoperfluorooctanoate were initiated by the macroinitiator in the presence of additional catalyst. The characterization of the block copolymers was performed by gel permeation chromatography, ¹H‐NMR spectroscopy, and differential scanning calorimetry. The surface activities of the block copolymers in toluene were investigated with the Wilhelmy plate method. The solid surface energy of the block copolymers was determined by measurement of the contact angles. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2625–2633, 2002     

Synthesis and characterization of poly(ester amide)s containing crystallizable amide segments

High molecular weight segmented poly(ester amide)s were prepared by melt polycondensation of 1,4-butanediol, dimethyl adipate and a preformed bisamide-diol based on 1,4-diaminobutane and ε-caprolactone. By varying the ratio of the bisamide-diol and 1,4-butanediol, a series of polymers was obtained with a hard segment content between 10 and 85 mol%. FT-IR and WAXD analysis revealed that the poly(ester amide)s crystallize in an α-type phase similar to the α-phase of even-even nylons. These polymers all have a micro-phase separated structure with an amide-rich hard phase and an ester-rich flexible soft phase. The polymers have a low and a high melt transition, corresponding with the melting of crystals comprising single ester amide sequences and two or more ester amide sequences, respectively. The low melt transition is between 58 and 70 °C and is independent of polymer composition. By increasing the hard segment content from 10 to 85 mol% the high melt transition increased from 83 to 140 °C while the glass transition temperature increased from −45 to −5 °C. Likewise, the elastic modulus increased from 70 to 524 MPa, the stress at break increased from 8 to 28 MPa while the strain at break decreased from 820 to 370%. Thermal and mechanical properties can thus be tuned for specific applications by varying the hard segment content in these segmented polymers.     

环氧化顺丁橡胶与NaHSO3反应制备磺化顺丁橡胶离聚体

研究了环氧化顺丁橡胶溶液在以四乙基溴化铵为相转移催化剂、N,N-二甲基苯胺为开环催化剂的条件下,与NaHSO3的水溶液反应制备磺化顺丁橡胶离聚体.结果表明:该离聚体的磺化度可达到1.77 mmol/g;随着离聚体离子含量的增加,吸水率增加,吸油率降低,离聚体稀溶液的黏度增加,表明了离子基团的存在.     

Synthesis of biodegradable and biocompatible ABC triblock copolymers

A facile approach is offered to synthesize well‐defined amphiphilic ABC triblock copolymers composed of poly(ethylene glycol) monomethyl ether (MPEO) as A block, poly(L ‐lysine) (PLLys) as B block, and poly(ε‐caprolactone) (PCL) as C block by a combination of ring‐opening polymerization (ROP) and click reactions. The propargyl‐terminated poly(Z‐L ‐lysine)‐block‐poly(ε‐caprolactone) (MPEO‐PzLLys‐PCL) diblock copolymers were synthesized via the ring‐opening polymerization of N^ε‐carbobenzoxy‐L ‐lysine N‐carboxyanhydride (Z‐L ‐Lys NCA) in DMF at room temperature using propargyl amine as an initiator and the resulting amino‐terminated poly(Z‐L ‐lysine) then used in situ as a macroinitiator for the polymerization of ε‐caprolactone in the presence of stannous octoate as a catalyst. The triblock copolymers poly(ethylene glycol) monomethyl ether –block‐poly(Z‐L ‐lysine)‐block‐poly(ε‐caprolactone) (MPEO‐PzLLys‐PCL) were synthesized via the click reaction of the propargyl‐terminated PzLLys‐PCL and azido‐terminated poly(ethylene glycol) monomethyl ether (PEO‐N₃) in the presence of CuBr and 1,1,4,7,7‐pentamethyldiethylenetriamine (PMDETA) catalyst system. After the removal of Z groups of L ‐lysine units, amphiphilic and biocompatible ABC triblock copolymers MPEO‐PLLys‐PCL were obtained. The structural characteristics of these ABC triblock copolymers and corresponding precursors were characterized by NMR, IR, and GPC. These results showed the click reaction was highly effective. Therefore, a facile approach is offered to synthesize amphiphilic and biocompatible ABC triblock copolymers consisting of polyether, polypeptide and polyester. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Synthesis and characterization of novel biodegradable triblock copolymers from L-Lactide,glycolide, and PPG

Copolymers with a PPG center block and two arms of random glycolide/lactide copolymers have been synthesized and characterized. Compared to random glycolide/lactide copolymers, these new polymers have high toughness and low elastic modulus.¹ H-NMR spectral lines of glycolide CH₂ protons of the copolymers are essentially identical. These materials show no crystallization transition in DSC thermograms and their melting points with respect to PLLA appeared at lower temperatures, indicating the pivotal role of the PPG center block in the copolymer. Degradation in aqueous media (pH = 6.9, 70°C) with stirring, subjected the two end blocks to hydrolytic degradation. The glycolyl ester bond cleavage was faster than for the lactyl ester bond. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 633–637, 1999     

Synthesis and characterization of diblock,triblock, and multiblock copolymers containing poly(3‐hydroxy butyrate) units

A poly[(R,S)‐3‐hydroxybutyrate] macroinitiator (PHB‐MI) was obtained through the condensation reaction of poly[(R,S)‐3‐hydroxybutyrate] (PHB) oligomers containing dihydroxyl end functionalities with 4,4′‐azobis(4‐cyanopentanoyl chloride). The PHB‐MI obtained in this way had hydroxyl groups at two end of the polymer chain and an internal azo group. The synthesis of ABA‐type PHB‐b‐PMMA block copolymers [where A is poly(methyl methacrylate) (PMMA) and B is PHB] via PHB‐MI was accomplished in two steps. First, multiblock active copolymers with azo groups (PMMA‐PHB‐MI) were prepared through the redox free‐radical polymerization of methyl methacrylate (MMA) with a PHB‐MI/Ce(IV) redox system in aqueous nitric acid at 40°C. Second, PMMA‐PHB‐MI was used in the thermal polymerization of MMA at 60°C to obtain PHB‐b‐PMMA. When styrene (S) was used instead of MMA in the second step, ABCBA‐type PMMA‐b‐PHB‐b‐PS multiblock copolymers [where C is polystyrene (PS)] were obtained. In addition, the direct thermal polymerization of the monomers (MMA or S) via PHB‐MI provided AB‐type diblocks copolymers with MMA and BCB‐type triblock copolymers with S. The macroinitiators and block copolymers were characterized with ultraviolet–visible spectroscopy, nuclear magnetic resonance spectroscopy, gel permeation chromatography, cryoscopic measurements, and thermogravimetric analysis. The increases in the intrinsic viscosity and fractional precipitation confirmed that a block copolymer had been obtained. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 1789–1796, 2004     

Synthesis and characterization of dendritic-linear-dendritic triblock copolymers based on poly(amidoamine) and polystyrene

Dendritic-linear-dendritic triblock copolymers composed of linear polystyrene (PSt) and poly(amidoamine) dendrons have been successfully synthesized. Two bromines-terminated PSt with M_n = 13,000 was prepared by atom transfer radical polymerization (ATRP) using α,α′-dibromo-p-xylene as initiator. Then the terminal bromines at both ends of PSt chains were replaced by one imine group of piperazine (PZ), and further Michael addition reaction of terminal PZ with excess 1,3,5-triacryloylhexahydro-1,3,5-triazine (TT) produced the first generation (G₁) of the triblock copolymer. Continuous growth of dendrons from G1.5 to G4 at the both ends of PSt chains was carried out by the iterative Michael addition reactions with excess PZ and following TT. The ABA triblock copolymers composed of the G₁-G₄ dendrons and the linear PSt were obtained. Structures of the triblock polymers were characterized by GPC and ¹H NMR spectra. Thermal phase transitions of the polymers were studied by DSC measurements, and all of the copolymers displayed a glass transition temperature.