Two‐sided comb poly(amic ester)–poly(propylene oxide) graft copolymers as porous polyimide precursors

New step‐growth graft block copolymers were synthesized. These two‐sided comb copolymers consisted of a poly(amic ester) (PAE) backbone and pendant poly(propylene oxide) (PPO) grafts. The copolymers were made via a macromonomer approach, in which the 4,6‐bischlorocarbonyl isophthalic acid bis[poly(propylene oxide)] ester macromonomer was synthesized through the reaction of hydroxyl‐terminated PPO oligomers with pyromellitic dianhydride and oxalyl chloride. This macromonomer was subsequently used in step‐growth polymerization with comonomers 4,6‐bischlorocarbonyl isophthalic acid diethyl ester, 2,5‐bischlorocarbonyl terephthalic acid diethyl ester, and 2,2‐bis[4‐ (4‐aminophenoxy)phenyl] hexafluoropropane, and this yielded PPO‐co‐PAE graft copolymers. Accordingly, we report the synthesis and characterization of the PPO oligomer, the PPO macromonomer, and their corresponding PPO‐co‐PAE graft copolymers. Graft copolymers with PPO concentrations of 3–26 wt % were synthesized. These polymers were thermally cured to produce polyimide/PPO composites. The thermolysis of these polyimide/PPO composites yielded porous polyimide films with porosities ranging of 4–22.5%. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2266–2275, 2005     

SYNTHESIS AND CHARACTERIZATION OF AMPHIPHILIC GRAFT COPOLYMER CONTAINING MICROPHASE SEPARATED AND LONG POLY(ETHYLENE OXIDE) SIDE CHAIN STRUCTURES**

Acryloyl terminated Poly (ethyleneoxide)macromonomers (PEO-A) with different PEO chain lengths have been prepared by deactivation of PEO alkoxide with acryloyl chloride. A new kind of amphiphilic polystyrene-g-poly (ethylene oxide)graft copolymer containing both microphase separated and PEO side chain structures has been synthesized from radical copolymerization of PEO-A macromonomer with styrene. After careful purification by a newly-developed method called "selective dissolution', the well-defined structure of the purified copolymers was confirmed by IR, ~1H-NMR and GPC. Various experimental parameters controlling the copolymerization were studied in detail. The results indicated that the feed ratio of styrene to macromonomer(S/M) was the most important determining factor for the composition of the copolymers. A detailed "comb- model" was proposed to describe the molecular structure of the graft copolymers. Finally, this amphiphilic graft copolymers may readily form microphase separated structures as clearly indicated by transmission electron microscopy.     

原子转移自由基聚合制备聚(丙二醇-g-苯乙烯)

以氯甲基化苯氧基聚丙二醇 (CMPOPPG)为大分子引发剂 ,由CuCl/bpy催化的苯乙烯原子转移自由基聚合反应合成了聚 (丙二醇 g 苯乙烯 ) .CMPOPPG经环氧丙烷 (PO)与缩水甘油苯基醚 (GPE)的开环聚合和氯甲基化反应制得 .接枝聚合反应具有可控性 .用1H NMR和微库仑分析法对接枝共聚物进行了表征 .结果表明 ,支链分子量可控 ,接枝率可达 8.6.     

Synthesis and Functionalization of Isotactic Poly(propylene) Containing Pendant Styrene Groups

Summary: Copolymerization of propylene and 1,4‐divinylbenzene was successfully performed by a MgCl₂‐supported TiCl₄ catalyst, yielding isotactic poly(propylene) (i‐PP) polymers containing a few pendant styrene groups. With a metalation reaction with butyllithium and a hydrochlorination reaction with dry hydrogen chloride, the pendant styrene groups were quantitatively transformed into benzyllithium and 1‐chloroethylbenzene groups, respectively, which allowed the synthesis of i‐PP‐based graft copolymers by living anionic and atom transfer radical (ATRP) polymerization mechanisms.

The incorporation of styrene pendant groups into isotactic poly(propylene) using a Zeigler–Natta catalyst gave functionalized polymers able to undergo living anionic and atom transfer radical (ATRP) polymerizations.     

β-蒎烯嵌段、接枝共聚物的合成

分别使用苯乙烯 HCl加成物 (a)和 2 氯乙基乙烯基醚 HCl加成物 (b)作为引发剂 ,TiCl4 Ti(OiPr) 4(3∶1mol mol)为活化剂 ,在nBu4NCl存在下 ,- 40℃、CH2 Cl2 中 ,通过顺序活性阳离子聚合 ,合成了 β 蒎烯与苯乙烯、对甲基苯乙烯的嵌段共聚物 .又用带丙烯酰氧功能基的引发剂c [CH3CH (OCH2 CH2 X )Cl,X =OCOC(CH3)CH2 ]引发 β 蒎烯活性阳离子聚合 ,合成了 β 蒎烯大分子单体 .该大分子单体在AIBN引发下与甲基丙烯酸甲酯进行自由基共聚 ,获得主链为聚甲基丙烯酸甲酯、侧链为聚 β 蒎烯的接枝共聚物     

含氟两亲接枝共聚物的制备及其与牛血清蛋白作用的研究

用端基反应法合成了对乙烯基苄基的聚乙二醇大分子单体,将该大分子单体与甲基丙烯酸六氟丁酯共聚,合成了一种含氟两亲接枝共聚物.利用1H-NMR1、9F-NMR、GPC对大分子单体和两亲接枝共聚物进行了表征.表面张力法测定了两亲接枝共聚物的临界胶束浓度,发现随着共聚物中含氟链段含量的增加,其临界胶束浓度降低.采用荧光光谱研究了含氟两亲接枝共聚物与牛血清蛋白(BSA)的相互作用,结果表明由于含氟链段疏水力的作用,含氟两亲接枝共聚物能与牛血清蛋白发生相互作用使其荧光增强,随着含氟两亲接枝共聚物浓度和共聚物中含氟链段含量的增加,荧光增强幅度加大.通过透射电子显微镜(TEM)和激光光散射粒度仪(PCS)测试发现,当BSA加入到含氟两亲接枝共聚物的胶束溶液后,所得胶束的粒径和粒径分布变大,共聚物胶束由规整的实心核壳结构变为囊泡状核壳结构.     

Synthesis, Purification and Characterization of Amphiphilic and Microphase Separated Graft Copolymer Polystyrene-g-Poly(ethylene oxide)

The present paper covers the poly (ethylene oxide) macromer with vinyl benzyl terminal group (PEO-VB) prepared by deactivation of the alkoxide function of mono-functional "living" PEO chains with vinyl benzyl chloride (VBC). The obtained macromers were subjected to careful purification and detailed characterization. A new kind of amphiphilic polystyrene-g-poly(ethylene oxide) (PS-g-PEO) with both mi-crophase separated and PEO side chains was synthesized from radical copolymerization of PEO-VB macromer with styrene monomer. An improved purification method, referred as "selective dissolvation", was established for the isolation of graft copolymers from the grafting products, and the purity and yield of the purified copolymers were satisfactory. The well-defined structure of the purified copolymers was confirmed by IR, 1H NMR and GPC. The bulk composition of the graft copolymers was determined by a well-established first derivative UV spectrometry. Various experimental parameters controlling the copolymeri     

以两亲性共聚物为模板溶胶-凝胶法制备WO3多孔薄膜及其 氢致变色特性的研究

报道了以六氯化钨为原料, 以两亲性的无规共聚物聚苯乙烯-co-聚烯丙醇(PS-co-PAAL)和三嵌段共聚物聚氧乙烯-b-聚氧丙烯-b-聚氧乙烯(PEO-b-PPO-b-PEO)为模板, 采用溶胶-凝胶法制备了WO3多孔薄膜. 利用热重分析仪(TGA)、粉末X射线衍射仪(XRD)、扫描电子显微镜(SEM)、原子力显微镜(AFM)等表征手段, 研究了模板和热处理温度对薄膜孔结构的影响; 并通过H2敏测试以及利用紫外可见分光光度计(UV), 研究了薄膜的氢敏性能和着色前后的透射光谱. 结果表明, 以无规共聚物PS-co-PAAL为模板制得的WO3薄膜, 经400 ℃热处理后, 可得到呈交联网状的多孔结构, 并表现出最佳的氢致变色性能.     

Amphiphilic graft copolymers - preparation and interfacial properties

Amphiphilic graft copolymers containing poly(ethylene oxide) (PEO) grafts have been prepared by various methods, for example, by coupling of reactive hydrophobic backbone polymers with end-functionalised PEO, by macromonomer copolymerisation, and by anionic graft polymerisation of EO onto polymer backbones carrying functional groups as initiator precursors. The graft copolymers are amphiphilic and were shown to accumulate at surfaces and interfaces in solution and in the solid state. Amphiphilic starch derivatives were prepared by reaction of amylose and starch with aliphatic α-epoxides.     

Synthesis of Graft Polymers by Copolymerization of Macromonomer. III. Preparation and Copolymerization of Styrene-Terminated Poly(Oxyethylene) Macromonomer

Styrene-terminated poly(oxyethylene) macromonomers (SOE) with narrow molecular weight distribution and quantitative styrene monofunc-tionality were synthesized. In homopolymerization of SOE, conversion of monomer to polymer was shown to be low in spite of high consumption of the vinyl groups of the SOE molecules. Free-radical copolymer-ization of the macromonomer with methyl methacrylate and styrene occurred smoothly, as opposed to homopolymerization. Cumulative copolymer composition and total conversion were determined from the conversions of macromonomer and comonomer (by weight changes) and by proton NMR of the copolymer. The monomer reactivity ratios were found to be r_a = 0.06 and r_b = 2.0 for the copolymerization of SOE macromonomer (a) with methyl methacrylate (b). In this case the macromonomer exhibited considerably lower reactivity than predicted from its low molecular weight model compound. The monomer reactivity ratios estimated for SOE and styrene were r_a = 0.86 and r_b = 1.20. The reactivity of SOE was comparable to, but somewhat lower than, styrene. The graft copolymers were used as activators in the halogen displacement reaction, and it was found that their catalytic activity depends on copolymer composition and chemical structure.     

Synthesis and characterization of model block-graft copolymers via anionic polymerization: Introduction of poly(isoprene) and poly(ethylene oxide) as graft chains

New architectural graft copolymers were prepared, that is, the graft chains were situated in terminal or center position of the backbone chain. These graft copolymers were termed block-graft copolymers. Two different block-graft copolymers were prepared from a “grafting onto” process and a “grafting from” process via living anionic polymerization. These backbone chains are poly(styrene), and the graft chains are poly(isoprene) and poly(ethylene oxide). The polymers were characterized by GPC measurements, osmometry, and ultracentrifugation. The block-graft copolymers formed fine microphase separation structures. It was a morphological feature that an apparent volume fraction of the graft to the backbone might be higher than the real volume fraction.     

温敏两亲性接枝物PAM-g-PNIPAm的合成及表征

以巯基乙胺为分子量调节剂,以丙烯酰氯作为链端转化剂合成了不同分子量的端丙烯酰胺基聚(N-异丙基丙烯酰胺)(PNIPAm)大分子单体;与丙烯酰胺共聚合,合成了以PNIPAm为侧链的接枝聚丙烯酰胺.用FTIR和¹HNMR方法表征了接枝聚合物与大分子单体的组成.该接枝聚合物在水溶液中具有热缔合特性及明显的温敏增稠性,水溶液的粘度在32～50℃之间随温度增加而增加.     

分散聚合制备聚苯乙烯/聚氧乙烯两亲聚合物微球

聚乙二醇在NaH的作用下和对氯甲基苯乙烯反应制得聚氧乙烯大分子单体 ,然后在乙醇 /水的介质中通过聚氧乙烯大分子单体和苯乙烯的分散共聚制得粒径范围在 0 5～ 1 5 μm ,粒径分布接近单分散的两亲聚合物微球 .对影响微球粒径和粒径分布的各个因素进行了研究 .     

Synthesis of Block Copolyamides by End-Reactive Oligomers

Block copolyamides having poly(propylene oxide) units in main chains were prepared by interfacial polyconden-sation using hydroxyl-terminated poly(propylene oxide), acid chloride and diamine. Block copolyamides having poly(styrene) segments were also prepared by the same technique by using endcaped poly(styrene) with carboxyl or amine end groups. They were characterized by spectroscopic, thermal and X-ray analyses.

Platlet adhersion behaviors were evaluated on the surface of these block copolyamides and it was found that the platelet adhersion and aggregation were greatly influenced by the domain size as well as the distribution of the block units in the block polyamides. Bio-compatibilities of these block po-lyamides were discussed in respect of microphase-separated domain structures.     

Synthesis and crystallization behavior study of syndiotactic polystyrene‐g‐isotactic polypropylene (sPS‐g‐iPP) graft copolymers

Based on coordination polymerization mechanism only, novel stereoregular graft copolymers with syndiotactic polystyrene main chain and isotactic polypropylene side chain (sPS‐g‐iPP) were synthesized via two steps of catalytic reactions. First, a chain transfer reaction was initiated by a chain transfer complex composed of a styrene derivative, 1,2‐bis(4‐vinylphenyl)ethane, and hydrogen in propylene polymerization mediated by rac‐Me₂Si[2‐Me‐4‐Ph(Ind)]₂ZrCl₂ and MAO, which gave iPP macromonomer bearing a terminal styryl group (iPP‐t‐St). Then the iPP‐t‐St macromonomers of varied molecular mass were engaged in syndiospecific styrene polymerization over a typical mono‐titanocene catalyst (CpTiCl₃/MAO) under different conditions to produce sPS‐g‐iPP graft copolymers of varied structure. With an effective purification process, well‐defined sPS‐g‐iPP copolymers were obtained, which were then subjected to differential scanning calorimetry (DSC) and polarized optical micrograph (POM) studies. The graft copolymers were generally found with dual melting and crystallization temperatures, which were ascribable respectively to the sPS backbone and iPP graft. However, it was revealed that the two segments displayed largely different melting and crystallization behaviors than sPS homopolymer and the precursory iPP‐t‐St macromonomer. Consequently, the graft copolymer exhibited much distinctive crystalline morphologies when compared with their individual components. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011.     

Poly(vinyl chloride)–poly(ethylene oxide) block copolymers: Synthesis and characterization

Poly(vinyl chloride)-poly(ethylene oxide) block copolymers have been synthesized in solution and emulsion. The polymers were made by first synthesizing macroazonitriles through the reaction of 4,4′-azobis-4-cyanovleryl chloride with hydroxy-terminated poly(ethylene oxide) of varying molecular weights. These macroazonitriles had molecular weights in the range of 3000–88,000 and degrees of polymerization from 5 to 24. Thermal decomposition of the azolinkages in the presence of vinyl chloride monomer yielded block copolymers containing form 2 to 20 wt % poly(ethylene oxide). The structures of the block copolymers were characterized by spectrometric, elemental and molecular weight analyses. The possibility of some graft polymerization occurring via free-radical extraction of a methylene hydrogen from the poly(ethylene oxide) was considered. Polymerization of vinyl chloride with an azonitrile initiator in the presence of a poly(ethylene oxide) yielded predominately homopolymer with some grafted poly(vinyl chloride).     

Syntheses of graft and star copolymers possessing polyolefin branches by using polyolefin macromonomer

Graft and star copolymers having poly(methacrylate) backbone and ethylene–propylene random copolymer (EPR) branches were successfully synthesized by radical copolymerization of an EPR macromonomer with methyl methacrylate (MMA). EPR macromonomers were prepared by sequential functionalization of vinylidene chain‐end group in EPR via hydroalumination, oxidation, and esterification reactions. Their copolymerizations with MMA were carried out with monofunctional and tetrafunctional initiators by atom transfer radical polymerization (ATRP). Gel‐permeation chromatography and NMR analyses confirmed that poly(methyl methacrylate) (PMMA)‐g‐EPR graft copolymers and four‐arm (PMMA‐g‐EPR) star copolymers could be synthesized by controlling EPR contents in a range of 8.6–38.1 wt % and EPR branch numbers in a range of 1–14 branches. Transmission electron microscopy of these copolymers demonstrated well‐dispersed morphologies between PMMA and EPR, which could be controlled by the dispersion of both segments in the range between 10 nm and less than 1 nm. Moreover, the differentiated thermal properties of these copolymers were demonstrated by differential scanning calorimetry analysis. On the other hand, the copolymerization of EPR macromonomer with MMA by conventional free radical polymerization with 2,2′‐azobis(isobutyronitrile) also gave PMMA‐g‐EPR graft copolymers. However, their morphology and thermal property remarkably differed from those of the graft copolymers obtained by ATRP. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 5103–5118, 2005     

Polystyrene‐graft‐poly(ethylene oxide) copolymers prepared by macromonomer technique in dispersion. I. Liquid chromatographic separation of product mixtures

Products of the radical dispersion copolymerization of methacryloyl‐terminated poly(ethylene oxide) (PEO) macromonomer and styrene were separated and characterized by size exclusion chromatography (SEC), full adsorption‐desorption (FAD)/SEC coupling and eluent gradient liquid adsorption chromatography (LAC). In dimethylformamide, which is a good solvent for PEO side chains but a poor solvent for polystyrene (PS), amphiphilic PS‐graft‐PEO copolymers formed aggregates, which were very stable at room temperature even upon substantial dilution. The aggregates disappeared at high temperature or in tetrahydrofuran (THF), which is a good solvent for both homopolymers and for PS‐graft‐PEO. FAD/SEC procedure allowed separation of homo‐PS from graft‐copolymer and determination of both its amount and molar mass. Effective molar mass of graft‐copolymer was estimated directly from the SEC calibration curve determined with PS standards. Presence of larger amount of the homo‐PS in the final graft‐copolymer products was also confirmed with LAC measurements. The results indicate that there are at least two or maybe three polymerization loci; namely the continuous phase, the particle surface layer and the particle core. The graft copolymers are produced mainly in the continuous phase while PS or copolymer rich in styrene units is formed mostly in the core of monomer‐swollen particles. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 2284–2291, 2000     

Synthesis of block and graft copolymers of β-pinene and styrene by transformation of living cationic polymerization to atom transfer radical polymerization

The transformations of living cationic polymerization to ATRP to form the block and graft copolymers of β-pinene with styrene were performed. Poly(β-pinene) carrying benzyl chloride terminal [poly(β-p)StCl] was prepared by capping the living poly(β-pinene), which was obtained with 1-phenylethyl chloride/TiCl₄/Ti(OiPr)₄/nBu₄NCl initiating system, with a few units of styrene. Poly(β-p)StCl, in conjunction with CuCl and bpy, could initiate the ATRP of styrene and gave well-defined block copolymer of β-pinene and styrene. In contrast, tert-alkyl-chlorine-capped poly(β-pinene) [poly(β-p)Cl] obtained by living cationic polymerization of β-pinene per se without capping of styrene gave a mixture of desired block copolymers and unreacted poly(β-p)Cl due to the low initiating reactivity of poly(β-p)Cl. Brominated poly(β-pinene) synthesized by the quantitative bromination of poly(β-pinene) using NBS was also used to initiate the ATRP of styrene in the presence of CuBr and bpy to prepare the graft copolymer of β-pinene and styrene. The first-order kinetic characteristic and linear increment of molecule weight with the increasing of monomer conversion indicated the living nature of this ATRP grafting.     

Synthesis and Mechanical Properties of Polypropylene-based Polymer Hybrids via Controlled Radical Polymerization

Isotactic polypropylene-based graft copolymers linking poly(methyl methacrylate), poly(n-butyl acrylate) and polystyrene were successfully synthesized by a controlled radical polymerization with isotactic polypropylene (iPP) macroinitiator. The hydroxylated iPP, prepared by propylene/10-undecen-1-ol copolymerization with a metallocene/methyl-aluminoxane/triisobutylaluminum catalyst system, was treated with 2-bromoisobutyryl bromide to produce a Br-group containing iPP (PP-g-Br). The resulting PP-g-Br could initiate controlled radical polymerization of methyl methacrylate, n-butyl acrylate and styrene by using a copper catalyst system, leading to a variety of iPP-based graft copolymers with a different content of the corresponding polar segment. These graft copolymers demonstrated unique mechanical properties dependent upon the kind and content of the grafted polar segment.