Hybrid copolymerization of cyclic and vinyl monomers

In this work,we report the hybrid copolymerization of various cyclic monomers and vinyl monomers.Our studies demonstrate that 1-tert-butyl-4,4,4-tris-(dimethylamino)-2,2-bis[tris(dimethylamino) phophoranyliden-amino]-2 5,5-catenadi(phosphazene) (t-BuP 4) can catalyze the hybrid copolymerization of caprolactone (CL),lactide (LA) or cyclic carbonate ester with acrylate or methyl acrylate.However,the polymerization of cyclosiloxane with vinyl monomers yields two corresponding homopolymers,and the polymerization of lactone with acrylonitrile (AN) produces only polyacrylonitrile.Clearly,the extent of matching of activity between a monomer and an active center determines whether or not there is hybrid copolymerization.     

丙烯腈与衣康酸在DMSO/H_2O中的聚合及聚合物性能表征

采用丙烯腈 (AN)与衣康酸 (IA)为共聚单体 ,以偶氮二异丁腈为引发剂在混合介质二甲基亚砜 水(DMSO H2 O)中自由基沉淀共聚合 ,合成了高分子量的聚丙烯腈 .通过正交设计方法研究了聚合反应条件 ,如反应温度、单体浓度、混合介质DMSO H2 O配比等对聚合反应的转化率的影响 ,还重点探讨了混合介质DMSO H2 O配比对转化率和粘均分子量的影响 .采用DSC ,TG ,IR等手段研究了PAN均聚物及 (PAN co IA)的结构与性能 .研究结果表明 ,增加反应温度 ,降低单体浓度 ,降低喂料AN IA配比中IA的含量 ,均有利于提高聚合反应的转化率 .AN与IA共聚反应的转化率随着反应介质中DMSO含量的增加而降低 ,同时聚合物的粘均分子量也降低 .对于喂料AN IA配比中IA含量相同的P(AN co IA)共聚物 ,高分子量P(AN co IA)共聚物比常规低分子量的放热峰起始温度低 ,放热峰宽     

Facile synthesis of star‐shaped copolymers via combination of RAFT and ring opening polymerization

Reversible addition fragmentation chain transfer (RAFT) polymerization and bifunctional sparteine/thiourea organocatalyst‐mediated ring opening polymerization (ROP) were combined to produce poly(L ‐lactide) star polymers and poly(L ‐lactide‐co‐styrene) miktoarm star copolymers architecture following a facile experimental procedure, and without the need for specialist equipment. RAFT was used to copolymerize ethyl acrylate (EA) and hydroxyethyl acrylate (HEA) into poly(EA‐co‐HEA) co‐oligomers of degree of polymerization 10 with 2, 3, and 4 units of HEA, which were in turn used as multifunctional initiators for the ROP of L ‐lactide, using a bifunctional thiourea organocatalytic system. Furthermore, taking advantage of the living nature of RAFT polymerization, the multifunctional initiators were chain extended with styrene (poly((EA‐co‐HEA)‐b‐styrene) copolymers), and used as initiators for the ROP of L ‐lactide, to yield miktoarm star copolymers. The ROP reactions were allowed to proceed to high conversions (>95%) with good control over molecular weights (ca. 28,000‐230,000 g/mol) and polymer structures being observed, although the molecular weight distributions are generally broader (1.3–1.9) than those normally observed for ROP reactions. The orthogonality of both polymerization techniques, coupled with the ubiquity of HEA, which is used as a monomer for RAFT polymerization and as an initiator for ROP, offer a versatile approach to star‐shaped copolymers. Furthermore, this approach offers a practical approach to the synthesis of polylactide star polymers without a glove box or stringent reaction conditions. The phase separation properties of the miktoarm star copolymers were demonstrated via thermal analyses. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 6396–6408, 2009     

Multistimuli responsive ternary polyampholytes: Formation and crosslinking of coacervates

A series of multiresponsive ternary polyampholytes were prepared by free‐radical copolymerization of N‐(3‐aminopropyl) methacrylamide hydrochloride (APM), methacrylic acid (MAA), and N‐(2‐hydroxyethyl) acrylamide (HEA). APM and MAA were held at 1:1 molar ratio, while the HEA monomer feed was varied between 14 and 33 mol %. Compositional drift during polymerization was monitored by ¹H nuclear magnetic resonance, and minimized by adjusting the reactivity of MAA through its degree of ionization. The resulting polyampholytes phase‐separate from aqueous solution to form coacervate droplets, depending on HEA content, pH, ionic strength, and temperature. These coacervate droplets could be covalently crosslinked and the resulting hydrogel particles were found to swell with increasing ionic strength. Such soluble and microgel polyampholytes open opportunities for new multistimuli responsive biomaterials. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 2109–2118     

Free‐radical copolymerization of ethyl α‐hydroxymethylacrylate with methyl methacrylate by reversible addition–fragmentation chain transfer

The controlled free‐radical homopolymerization of ethyl α‐hydroxymethylacrylate and copolymerization with methyl methacrylate were performed in chlorobenzene at 70 °C by the reversible addition–fragmentation chain transfer polymerization technique with 2,2′‐azobisisobutyronitrile as the initiator. 2‐Phenylprop‐2‐yl dithiobenzoate and 2‐cyanoprop‐2‐yl dithiobenzoate were used as chain‐transfer agents in the homopolymerization, whereas only the former was used in the copolymerization. All reactions presented pseudolinear kinetics. The effect of the monomer feed ratio on the copolymerization kinetics was examined. The conversion level decreased when the proportion of ethyl α‐hydroxymethylacrylate in the monomer feed was larger. Kinetic studies indicated that the radical polymerizations proceeded with apparent living character according to experiments, demonstrating an increase in the molar mass with the monomer conversion and a relatively narrow molar mass distribution. All copolymers were statistical in chain structure, as confirmed by determinations of the monomer reactivity ratios. The monomer reactivity ratios were determined, and the Mayo–Lewis terminal model provided excellent predictions for the variations of the intermolecular structure over the entire conversion range. Additionally, the chemical modification of poly(ethyl α‐hydroxymethylacrylate) was carried out to introduce glucose pendant groups into the structure. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 5618–5629, 2006     

Electrosyntheses of high‐quality freestanding poly(fluorene‐co‐3‐methylthiophene) films with tunable fluorescence properties

The copolymerization of 3‐methylthiophene (MeT) and fluorene (FE) was successfully achieved in boron trifluoride diethyl etherate by the direct anodic oxidation of the monomer mixtures on a platinum electrode. The optimal feed ratio together with the best suitable potential for their copolymerization was determined. The as‐formed copolymer films, which were copolymerized with a feed ratio of FE/MeT = 2:1 at a constant potential of 1.3 V (vs a saturated calomel electrode), had the advantages of both poly(3‐methylthiophene) and polyfluorene, such as good electrochemical behavior, high conductivity, excellent thermal stability, and high film quality. The structure of the copolymer was investigated with ultraviolet–visible, infrared spectroscopy, and thermal analysis. Fluorescence spectroscopy studies revealed that the dedoped copolymer film in the solid state was a good blue‐light emitter with a strong emission at 435 nm and a shoulder at 459 nm. The emitting properties of the copolymer could be tuned by parameters during the electrochemical polymerization, such as the applied potential and monomer feed ratio. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 4904–4915, 2006     

吡啶基有机碱催化O-羧基酐的活性开环聚合

O-羧基酐(OCA)是α-羟基酸与三光气的缩合产物, 其侧基结构丰富, 可开环聚合生成结构多样的聚α-羟基酸, 弥补了聚乳酸结构和性能单一的缺陷. 在OCA开环聚合过程中, 手性α-H容易发生外消旋化, 导致聚合物的立构规整度下降. 本文发现了一种结构简单的高性能有机催化剂—4-甲氧基吡啶, 其可在温和的条件下快速催化OCA的活性开环聚合, 有效抑制酯交换和手性α-H的外消旋化副反应, 合成出高立构规整度的窄分布聚α-羟基酸. 进一步研究发现, 虽然在甲苯和四氢呋喃等常见溶剂中, OCA的开环聚合遵循一级动力学, 但在环氧烷烃溶剂中, OCA开环聚合遵循零级动力学, 聚合反应速率与单体浓度无关. 作为新型高效有机碱催化剂, 4-甲氧基吡啶在多嵌段可降解聚酯高效合成和聚酯生物医药载体制备等方面具有潜在的应用价值.     

以二氟烷基磺酸修饰的聚降冰片烯为基础的聚合物电解质薄膜的制备

合成了一种新型的二氟烷基磺酰氟单体2-（双环[2.2.1]庚-5-烯-2）-1,1-二氟-2-甲氧基丙基-1-磺酰氟.首先利用二氟甲基2-吡啶基砜和2-乙酰基-5-降冰片烯发生亲核加成反应,在低温下用三氟甲磺酸甲酯保护加成产物中的羟基,之后在KOH/MeOH的条件下脱去吡啶基,得到的二氟亚磺酸盐和Slectfluor试剂反应制得想要的二氟烷基磺酰氟单体.这种新型的二氟烷基磺酰氟单体和不同比例的降冰片烯单体在Grubbs第二代催化剂存在条件下进行开环烯烃复分解聚合（ROMP）,所得的聚合物在碱性条件下水解,再用稀盐酸处理最终制得新型的含有二氟烷基磺酸的聚合物电解质膜.这些新型的聚合物电解质膜具有中等的室温质子电导（12～49mS/cm）.     

一种新颖丙烯腈基含糖共聚物的合成和表征

利用无保护的糖内酯与甲基丙烯酸-2-氨乙基酯盐酸盐反应高效简便合成了一种新颖的直链糖,并用水相沉淀聚合的方法将其与丙烯腈进行了共聚合。考察了单体配比、聚合时间、引发剂浓度和总单体浓度对聚合行为的影响,红外、核磁用来表征聚合物,证明水相沉淀聚合是一种有效的聚合方式。     

Emulsion copolymerization of styrene and methyl methacrylate

Chain transfer constants to monomer have been measured by an emulsion copolymerization technique at 44°C. The monomer transfer constant (ratio of transfer to propagation rate constants) is 1.9 × 10^?5 for styrene polymerization and 0.4 × 10^?5 for the methyl methacrylate reaction. Cross-transfer reactions are important in this system; the sum of the cross-transfer constants is 5.8 × 10^?5. Reactivity ratios measured in emulsion were r₁ (styrene) = 0.44, r₂ = 0.46. Those in bulk polymerizations were r₁ = 0.45, r₂ = 0.48. These sets of values are not significantly different. Monomer feed compcsition in the polymerizing particles is the same as in the monomer droplets in emulsion copolymerization, despite the higher water solubility of methyl methacrylate. The equilibrium monomer concentration in the particles in interval-2 emulsion polymerization was constant and independent of monomer feed composition for feeds containing 0.25–1.0 mole fraction styrene. Radical concentration is estimated to go through a minimum with increasing methyl methacrylate content in the feed. Rates of copolymerization can be calculated a priori when the concentrations of monomers in the polymer particles are known.     

稀土Schiff碱配合物催化烷基异氰酸酯室温聚合

利用Schiff碱稀土配合物Ln（H2Salen）2Cl3·2C2H5OH与AI（i—Bu）3组成的催化体系催化烷基异氰酸酯室温聚合,详细考察了催化剂组成以及聚合条件等对烷基异氰酸酯聚合的影响,并研究了己基异氰酸酯的聚合动力学．以La、Nd、Sm和Gd四种稀土元素为代表,合成了相应的Schiff碱配合物,结果表明轻稀土体系比重稀土体系好,La的聚合活性最高．在-40℃-40℃很宽的聚合温度范围内,可以得到分子量分布窄（MWD=1．50～2．40）的高分子量聚异氰酸酯,20℃为最佳的聚合温度．己基异氰酸酯的最佳聚合条件为：[AI]／[La]=30（摩尔比）,[n-HexNCO]／[La]=100,[n—HexNCO]=3．43mol／L,甲苯溶液中20℃聚合12h,聚合物收率74．0％,聚合物黏均分子量高达73．5×10^4,数均分子量40．2×10^4,MWD=1．79．聚合动力学研究表明己基异氰酸酯聚合反应对单体浓度和催化剂浓度都是一级关系,聚合反应活化能为43．64kJ／mol．     

Copolymerization of methyl acrylate and vinyl acetate catalyzed by ethylaluminium chlorides

The copolymerization of vinyl acetate with methyl acrylate in the presence of Et₂AlCl, Et_1.5AlCl_1.5, and Et₂AlCl-benzoyl peroxide systems has been investigated. The influence of monomer ratios and organoaluminium compound concentration on the copolymer yield and composition have been determined and discussed. The monomer sequences distribution has been studied by means of ¹³C-NMR. It was found that organoaluminium compounds in the studied systems catalyze not only the alternating copolymerization, but also the homopropagation of both monomers. An alternating copolymer was obtained in reactions carried out at ?78°C, when a large excess of vinyl acetate was used in the monomer feed.     

Enzymatic Ring-Opening Polymerization of Lactones by Lipase Catalyst: Mechanistic Aspects

Mechanistic aspects of lipase-catalyzed ring-opening polymerization (ROP) of lactones to give polyesters are discussed from accumulated experimental data and new insight. Comparison of the ROP reactivity by lipase catalyst with the anionic ROP reactivity by a metal-catalyst clearly demonstrates the characteristics of lipase catalysis; the larger ring-sized monomers with lower ring strain showed higher polymerizability than medium ring-sized ones, in contrast to the anionic ROP showing the reverse direction where the ring strain of monomer is operative. The enzyme-catalysis involves an acyl-enzyme intermediate formation as a key-step. From the copolymerization results a new mechanism is proposed, that involves the formation of the acyl-enzyme intermediate (acylation step) and/or the nucleophilic attack of the propagationg alcohol end to the carbonyl carbon of the intermediate to open the monomer ring (deacylation step) as the rate-determining step. The structure of the propagating alcohol end (primary or secondary) affects much on which step is more operative.     

具有广谱紫外屏蔽性能的三元共聚物微球的制备

以醋酸乙烯酯(VA)、 马来酸酐(MA)和商品化的紫外吸收剂2-{2-羟基-5-[2-(甲基丙烯酰氧)乙基]苯基}-2H-苯并三唑(NB)为单体, 偶氮二异丁腈(AIBN)为引发剂, 通过自稳定沉淀聚合法(2SP)制备了具有广谱紫外屏蔽性能的单分散三元共聚物微球(PVMN); 研究了溶剂、 单体配比、 引发剂用量、 单体浓度、 反应温度和反应时间对共聚物微球形态和性能的影响. 研究结果表明, 体积比为7∶3的苯甲酸乙酯/正庚烷混合溶剂是2SP法合成单分散PVMN微球的理想溶剂. 随着单体配比中紫外吸收单体NB比例的增加, 引发剂用量、 单体浓度、 反应温度的提高和反应时间的延长, 微球的粒径随之增大, 进而改变了微球的紫外屏蔽性能. 本文制备的微球的粒径范围为(249±19)~(1434±213) nm, 优化得到的PVMN微球可屏蔽约90%的紫外光. 该策略还可扩展到其它可用作紫外吸收剂的乙烯基单体, 是一种制备稳定高分子紫外屏蔽剂的通用方法.     

Synthesis of phosphonated copolymers with tailored architecture by reversible addition‐fragmentation chain transfer polymerization (RAFT)

The synthesis by reversible addition‐fragmentation chain transfer (RAFT) polymerization of three phosphonated terpolymers with tailored architecture has been studied. A phosphonated methacrylate (MAUPHOS) was copolymerized with vinylidene chloride (VC₂) and methyl acrylate (MA) to prepare a gradient terpolymer poly(VC₂‐co‐MA‐co‐MAUPHOS). Besides, hydroxyethyl acrylate (HEA) was used as a functional monomer in RAFT polymerization to prepare a statistical poly(VC₂‐co‐MA‐co‐HEA) terpolymer and a diblock poly(VC₂‐co‐MA)‐b‐poly(HEA) terpolymer. The HEA‐containing polymers were then modified with a phosphonated epoxide to introduce the phosphonated group. The control of the polymerization was proven by kinetic studies (evolution of molecular weight vs. conversion) and by a successful block copolymerization. The architecture of the terpolymers was determined by the reactivity ratios of the monomers: terpolymerization of VC₂, MA, and HEA leading to an ideal statistical terpolymer (no composition drift) whereas terpolymerization of VC₂, MA, and the phosphonated methacrylate led to a gradient terpolymer. These terpolymers were characterized by size exclusion chromatography, ³¹P NMR and differential scanning calorimetry. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 13–24, 2006     

烷基功能化聚烯丙基缩水甘油醚的制备及对PVC的增塑及抗静电作用

利用阴离子开环聚合(AROP)及巯基-烯点击反应相结合的路线构筑了一种新型烷基功能化聚醚, 考察了其对聚氯乙烯(PVC)的增塑及抗静电作用. 首先, 以烯丙基缩水甘油醚为单体, 利用AROP制备聚烯丙基缩水甘油醚(PAGE)中间产物; 然后, 以PAGE为前驱体, 借助巯基-烯点击反应将柔性烷基引入其侧链, 获得烷基功能化聚烯丙基缩水甘油醚(PAGE_butane)目标产物. 核磁共振波谱(NMR)及凝胶渗透色谱(GPC)结果表明, 所得聚合物结构与设计一致, 且PAGE的分子量可通过改变单体与引发剂的投料比灵活调控. 热性能研究结果显示柔性烷基的键入导致PAGE的玻璃化转变温度(T_g)进一步降低. PAGE_butane的T_g为-74.97 ℃, 且具有较好的热稳定性. PAGE_butane在不损失PVC强度的同时可明显提升其韧性, 同时可有效降低其表面电阻率, 产生一定的抗静电效果. 与邻苯二甲酸二(2-乙基)己酯(DOP)增塑剂相比, PAGE_butane体现出更优异的耐抽出及耐挥发性.     

Stabilizer-free precipitation copolymerization of renewable bio-based α-methylene-γ-butyrolactone and styrene

Stabilizer-free precipitation copolymerization of α-methylene-γ-butyrolactone (MBL) and styrene (St) was carried out in isoamyl acetate with BPO as initiator at 80°C. The influence of monomer feed ratio, initiator concentration and reaction time on the size and morphology of the obtained polymer particle was investigated in details. It was found that the monomer feed ratio play an important role on the particle formation process. When the monomer feed ratio of MBL to St was 1:2, narrow size distributed spherical polymer particles were formed with number average diameters in the range of 785–2620 nm. The formation process of polymer particle was studied to get a deep insight into the polymerization process of this reaction system. It was found that the formation mechanism of the poly(MBL-co-St) particles was similar to that of conventional precipitation polymerization. After a short nucleation stage (10 min), the amount of polymer particles remained constant and the particle growth mainly came from the capturing of newly formed polymer chains. The chemical composition and thermal property of the poly(MBL-co-St) were fully characterized by FTIR, ¹H-NMR spectra, and DSC.     

氯化原位接枝反应制备羟基官能化CPE——结构表征

以高密度聚乙烯(HDPE)为基体,采用气-固氯化原位接枝反应合成了以氯化聚乙烯(CPE)为骨架聚合物、丙烯酸-2羟基乙酯(HEA)为支链的接枝共聚物.反应中不需要加入任何引发剂,以氯自由基引发接枝及氯代反应,得到羟基官能化CPE接枝聚合物.并用1H-NMR,FT-IR,GPC及X-射线衍射等对接枝共聚物的结构进行了表征.     

Novel analytical method for the crosslinking process: Infrared thermographic analysis of the thermally latent cationic polymerization of a spiroorthoester and a bifunctional oxetane for the construction of a low‐shrinkage curing system

Thermal behaviors were monitored by infrared thermographic analysis in the copolymerization of a spiroorthoester and a bifunctional oxetane with thermally latent initiators [benzyl tetrahydrothiophenium hexafluoroantimonate (BTHT) and benzyl 4‐hydroxyphenyl methyl sulfonium hexafluoroantimonate (BPMS)]. The copolymerization with BPMS increased the temperature during the copolymerization more than that with BTHT, whereas the exothermicities were lowered with the increase in the initial feed ratio of the spiroorthocarbonate monomer. The high exothermicity in the copolymerization with BPMS is ascribable to the faster propagation of the oxetane monomer with a high heat of polymerization, and this is supported by model reactions and computational calculation. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 2820–2826, 2007     

Infrared thermographic analysis on copolymerization of spiroorthoester with oxetane

Infrared (IR) thermography was employed to monitor temperature changes during the copolymerization of a spiroorthoester monomer with an oxetane monomer initiated with a benzyl sulfonium salt. The temperature changes in the polymerizations decreased with the increase of the initial feed ratios of the spiroorthocarbonate monomer. For instance, the temperature in the copolymerization of the equimolar mixture of both of the monomers increased only ～1 °C, whereas that in the homopolymerization of the oxetane monomer increased more than 20 °C. This result indicates that the copolymerization employing spiroorthocarbonate monomers effectively suppress temperature increase, which are responsible to shrinkage during cooling. The suppression of polymerization shrinkage by spiroorthocarbonate was also confirmed by density measurement of the polymers using a gas pycnometer. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 1388–1393, 2007.