聚苯乙烯大单体与乙酸乙烯酯的共聚及其接枝共聚物的表征

研究了聚苯乙烯大单体与乙酸乙烯酯的溶液聚合,结果表明,接枝效率随引发剂用量、聚合温度及小单体与大单体的投料比的增加而增加,随大单体的分子量增加而减少,而随单体浓度的变化呈现一最大值。共聚过程中大单体的转化率开始较小单体的增加快,后期变慢。用萃取法纯化的接枝共聚物经GPC、IR、~1H-NMR及PGC等表征,并算得平均接枝数为4—7。透射电镜表明接枝共聚物中存在微观相分离。     

聚环氧乙烷大单体与丙烯酸乙酯的共聚及其规整接枝共聚物的表征

 本工作研完了末端为甲基丙烯酸酯型的聚环氧乙烷大单体与丙烯酸乙酯的溶液自由基共聚。结果表明,大单体接枝效率和共聚物分子量受单体总浓度、投料比、大单体分子量及引发剂等的影响,接枝效率最高可达90％以上,分子量可在5-15×10⁴范围内变化。丙烯酸乙酯与大单体共聚的竞聚率为0.83。共聚物用萃取法精制后,用IR、¹H-NMR、裂解色谱、GPC和膜渗透压计等进行了表征。证实产物有预期的规整接枝共聚物结构。平均接枝数为2—11。     

聚环氧乙烷大单体与丙烯酸乙酯的共聚及其规整接枝共聚物的表征

本工作研完了末端为甲基丙烯酸酯型的聚环氧乙烷大单体与丙烯酸乙酯的溶液自由基共聚。结果表明,大单体接枝效率和共聚物分子量受单体总浓度、投料比、大单体分子量及引发剂等的影响,接枝效率最高可达90％以上,分子量可在5-15×10~4范围内变化。丙烯酸乙酯与大单体共聚的竞聚率为0.83。共聚物用萃取法精制后,用IR、~1H-NMR、裂解色谱、GPC和膜渗透压计等进行了表征。证实产物有预期的规整接枝共聚物结构。平均接枝数为2—11。     

β-环糊精/聚(DL-丙交酯)接枝共聚物的合成与表征

以β-环糊精(β-CD)为接枝骨架、DL-丙交酯(DLLA)为接枝单体,三乙胺为催化剂,合成了β-环糊精/聚(DL-丙交酯)接枝共聚物(PCDLA).利用IR、1H-NMR、DSC、WXRD和GPC等方法对接枝共聚物的结构进行了表征,测定了共聚物的分子量,并研究了反应投料比对单体转化率(C%)、接枝率(G%)和接枝效率(GE%)的影响.结果表明,在三乙胺催化下,DL-丙交酯与β-环糊精能够发生聚合反应得到接枝共聚物,当DL-丙交酯与β-环糊精结构单元的摩尔比为30∶1,反应时间为10h时,接枝反应的接枝率(G%)和接枝效率(GE%)可分别达到182·9%和21·4%.随着接枝共聚物中β-环糊精含量的增加,共聚物的亲水性得到了改善.     

聚苯乙烯-甲基丙烯酸甲酯接枝共聚物的合成和表征

<正> 聚苯乙烯(PS)和聚甲基丙烯酸甲酯(PMMA)都是研究得十分深入的聚合物。它们的接枝共聚物,虽然在基础研究中是十分有兴趣的对象,但因传统的合成方法不能得到结构确定的产物,同时难于与伴生的均聚物分离,进展不大。近年来随着大分子单体方法和极性单体活性阴离子聚合的发展,具有确定结构的接枝共聚物PS-g-PMMA的合成逐步成为可能。例如:Ishizu采用阴离子聚合合成带乙烯基的PMMA大分子单体,再与苯乙烯自由基共聚的路线,Ballegoole等和Watanable分别采用主干接枝法,即用自     

聚氯乙烯-丙烯酸丁酯接枝共聚物的结构表征

以通用聚氯乙烯(PVC)和脱氯化氢PVC树脂为基体,采用悬浮溶胀接枝共聚法合成聚氯乙烯-丙烯酸丁酯接枝共聚物,对脱氯化氢PVC和接枝共聚物的结构进行了表征.结果表明,以碱液为介质加热PVC能脱除少量氯化氢,得到以链节数为2,3,4的共轭双键为主的不饱和结构,而树脂的分子量变化不大;在相同接枝反应条件下,采用脱氯化氢PVC与丙烯酸丁酯接枝共聚可以提高接枝率和接枝效率;PVC接枝共聚物的特性粘度随接枝率增加而增加,其重均分子量和分子量分布指数均大于接枝所用的PVC树脂.     

聚苯乙烯大分子单体与醋酸乙烯酯接枝共聚物的合成及表征

<正> 用大分子单体与小分子单体共聚是七十年代初才出现的合成接枝共聚物的一种新方法。通过共聚合反应而不是接枝反应同时形成主干及支链。这种接枝共聚物由于形成支链的大分子单体是预先合成的,其分子量分布较窄,又可调节控制,所以合成的接枝共聚物支链长短比较均一,副反应较少,链结构比较明确,因此也易于表征。     

乙酰丙酮铜(Ⅱ)引发淀粉与甲基丙烯酸甲酯接枝共聚合的研究

<正> 淀粉与丙烯酸酯类单体的接枝共聚物有可能作为生物降解塑料,而被应用于农业、医药及食品等各个方面。因此寻求价廉、高效的引发剂,以用于引发淀粉与烯类单体的接枝共聚,已引起了人们的极大兴趣。 过渡金属离子与β二酮的配合物,如乙酰丙酮铁(Ⅲ)、乙酰丙酮锰(Ⅲ)、乙酰丙酮铜(Ⅱ)等是一类引起注目的新型引发剂,已在羊毛、蚕丝、纤维素等天然大分     

蚕丝辐射接枝丙烯腈

以氯化锌水溶液为溶剂 ,用钴 60γ射线引发蚕丝均相溶液接枝丙烯腈 .研究了辐射吸收剂量、剂量率、铜离子浓度、蚕丝浓度和单体浓度及“后效应”对单体转化率、接枝率、接枝效率、接枝链分子量的影响 ;研究发现初始接枝效率主要取决于 [S]丝/ ( [S]丝 +[M]单) ,接枝效率随吸收剂量增加而增加 ;铜离子的存在使接枝链分子量下降 ,而对接枝率和接枝效率影响不大 ;用IR、TGA、DTA等多种方法对接枝物进行了表征 ,表明蚕丝接枝上聚丙烯腈后 ,其热学性能有较大提高 .     

PEB/MMA-AN悬浮接枝共聚反应机理

研究了乙烯-1-丁烯共聚物(PEB)弹性体与甲基丙烯酸甲酯(MMA)-丙烯腈(AN)悬浮接枝共聚反应行为及接枝共聚产物对SAN树脂增韧作用随反应时间的变化规律, 用凝胶渗透色谱法和傅里叶变换红外光谱法对接枝共聚产物进行了表征, 分析了接枝共聚反应机理, 推算了接枝链分子量. 结果表明, 体系首先发生链增长自由基向PEB转移终止形成非接枝共聚物(MAN_L)和PEB大分子自由基引发单体共聚形成接枝链(g-MAN)的反应, 接枝反应结束后体系发生明显的非接枝共聚形成非接枝共聚物(MAN_H)的反应; MAN_L的分子量低于g-MAN的分子量, 而g-MAN的分子量明显低于MAN_H的分子量; 在接枝共聚过程中发生已接枝和未接枝PEB断链并随机再接生成多嵌段共聚物的副反应; 在反应初期, 接枝链的AN单元含量接近于非接枝共聚物的AN单元含量, 在反应中后期前者远低于后者.     

EPR-g-PS接枝共聚物的大分子单体共聚物合成及表征

将阴离子聚合所得末端带有烯丙基的窄分布聚苯乙烯大分子单体(PSallyl)与乙烯、丙烯在钒催化体系下进行共聚合,得到聚苯乙烯(PS)支链沿乙丙橡胶(EPR)主干无规分布的接枝共聚物EPR-g-PS。接枝效率为70％左右。大分子单体的分子量、加入量,催化剂浓度和聚合温度等对共聚反应及其产物结构有明显的影响。丁酮为选择沉淀剂可分离未反应的聚苯乙烯大分子单体。用紫外光谱、核磁共振、渗透压和凝胶渗透色谱法测定了纯制接枝共聚物的组成和分子量。结果表明所合成的EPR-g-PS的聚苯乙烯含量为5—45％;支链为分子量1.0—7.8×10~4的窄分布((?)=1.05—1.17)聚苯乙烯;平均支链数为1—4。     

Ring-opening copolymerization of epoxy-terminated polystyrene macromer with epichlorohydrin and study on properties of the copolymers

The synthesis and ring-opening copolymerization of epoxy-terminated polystyrene (PS-ep) macromer with epichlorohydrin (ECH) as well as some properties of the graft copolymers, were studied. The results showed that content of the epoxy-terminated macromer in the crude macromer can be increased by anionic polymerization of styrene in cyclohexane, and capping with propylene sulfide, followed by termination with ECH at 0 °C. The ring-opening copolymerization of ECH with the macromer can be performed by using a quaternary catalyst system which was composed of triisobutyl aluminium-phosphoric acid-water-amine in the molar ratio of 1:0.25:0.25:0.1-0.15. When the charging weight percentage of PS-ep/ECH=25-65% and M_n of PS-ep was 2.6-10×10³, the conversion of ECH was greater than 95% and the conversion of the macromer or grafting efficiency was 35-65%. The purified copolymer was characterized by IR, ¹H NMR and dynamic viscoelastometer to be a copolymer of ECH with polystyrene (PS) grafts. Transmission electron microscope showed the existence of PS domains in the continuous phase of polyepichlorohydrin (PECH). In a certain range of compositions the graft copolymer behaves like a thermoplastic elastomer. The graft copolymer can be melted and processed repeatedly. Its oil and solvent resistance were better than PS and similar to PECH rubber. The graft copolymer can be used as a compatibilizer for blending PECH with PS to form thermoplastic elastomer blends. Only 2% of it based on the blend is needed to raise the tensile strength of the blends obviously.     

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     

Copolymerization reactivity of poly(methyl methacrylate) macromer

Poly(methyl mehtacrylate)(PMMA) macromers with several vinyl groups at both chain ends were synthesized by the mechanical scission reaction of the main chain in the presence of p-divinylbenzene(p-DVB). The radical copolymerization of this macromer with styrene(St) or MMA was carried out in benzene at 60°C and the reactivity ratio of both monomers (r₂) was calculated from a kinetic scheme of copolymerization. As a result, the effect of molecular weight and concentration of macromers was not observed in both copolymerization systems. The value of r₂, however, decreased as the number of end vinyl groups in a macromer (N) increased. These results are discussed in some detail as we describe the construction of the kinetic model of copolymerization.     

羧酸型接枝共聚物的合成及其络合物做化学阀

用大单体技术合成了带规整聚苯乙烯支链的聚丙烯酸接枝共聚物 .研究了各种聚合条件包括温度、时间、单体浓度、大单体分子量及大单体与小单体的投料比等对接枝效率、共聚物分子量的影响 .纯化的共聚物表现出良好的乳化性质及高吸水率 ,在稀溶液中的行为如同聚电解质 .此接枝共聚物与含规整聚氧乙烯支链的聚丙烯酸乙酯络合生成的大分子间络合物膜呈现化学阀的作用 ,水通过它的渗透速率能通过调节pH加以可逆地控制 .     

SYNTHESIS OF POLYACRYLAMIDE WITH PENDANT POLY(BUTYL ACRYLATE) CHAINS USING THE MACROMER TECHNIQUE AND STUDIES ON THEIR PROPERTIES

INTRODUCTIONSince Milkovich and Chiang[1] developed a method of preparing copolymers with uniform side chains by usingthe macromer technique, the synthesis of copolymers with uniform side chains from different macromers hasbeen studied extensively. Milkovich et al. reported the synthesis of polystyrene macromer through termination ofliving polystyrene anions with methacryloyl chloride and its copolymerization with butyl acrylate to formthermoplastic elastomer[2]. Rempp[3] obtained polyoxy…     

Synthesis,Characterization, and Conductivities of Poly(2-Vinylpyridine)-graft-Polyoxyethylene Using a Macromer Technique

Abstract

Poly(2-vinylpyridine) (P2-VP) with uniform polyoxyethylene (PEO) grafts was synthesized using a macromer technique. 2-Vinylpyridine was copolymerized with PEO macromer in solution by using azobisisobutyronitrile (AIBN) as the initiator. The effects of the amount of AIBN, the concentrations of 2-vinylpyridine and macromer, the number average molecular weight of macromer, and the charging ratio of macromer to 2-vinylpyridine in the copolymerization were studied. The copolymerization rate of the PEO macromer with 2-vinylpyridine was also investigated. The grafting efficiency reached about 56%. The crude graft copolymer was purified by extraction and precipitation, and it was characterized by IR, ¹H-NMR, and Bruss membrane osmometry. The PEO grafts were doped with LiClO₄ and showed ionic conductivity around 4.10 × 10^?6S°Cm^?1 at 25°C whereas the P2-VP main chains were complexed with TCNQ to obtain electronic conductivity around 5.50 × 10^?6 S°Cm^?1 at 25°C The mixed (ionic and electronic) conductivity of the doped copolymer could reach about 5.40 × 10^?5 S°Cm^?1 at 25°C and showed a synergistic effect.