以聚醚为主链的新型两亲性接枝共聚物的分子设计、合成及表征.doc

以聚醚为主链的新型两亲性接枝共聚物的分子设计、合成及表征

近年来，由于聚合技术的发展，特别是可控/“活性”自由基聚合技术的出现，使得人们能够设计合成出各种线形和非线形结构的共聚物。在这些共聚物中，由亲水链和憎水链组成的接枝共聚物，由于它们具有特殊的结构，丰富的自组装形态以及在化学、物理和生物领域中具有广泛的用途而引起人们的广泛兴趣。但是，就目前的两亲性接枝共聚物而言，其主链大部分是由憎水链组成的，而支链则由亲水链组成。由亲水主链和憎水支链组成的接枝共聚物，由于其合成的困难，迄今为止很少有文献报道。本文提出了一个合成该接枝共聚物的新方法，并在实践中成功地加以了实施。我们的主要结果如下：
 1. 利用传统的阴离子聚合技术，通过二缩三乙二醇与二苯甲基钾(DPMK)组成的引发剂体系首先引发1-乙氧基乙基-2,3-环氧丙醚（EPEE）均聚或其与环氧乙烷(EO)共聚，分别得到线形的窄分布的均聚物PEPEE和共聚物poly(EO-co-EPEE)。得到的聚合物用甲酸水解去保护，并在二氧六环和甲醇的混合溶剂中用氢氧化钾溶液皂化后，得到了聚合物链的侧端挂有羟甲基官能团的线形聚醚linear Polyglycidol (lPG)和poly(EO-co-Gly)。共聚物poly(EO-co-Gly)的羟基与2-溴异丁酰溴进行酯化反应，得到侧链挂有2-溴异丁酸酯基结构的可以用于原子转移自由基聚合(ATRP)聚合体系的大分子引发剂Poly(EO-co-Gly)ATRP。然后通过ATRP聚合技术，分别引发聚合了苯乙烯(St)、丙烯酸甲酯(MA)、丙烯酸叔丁酯(tBA)和甲基丙烯酸-2-(N, N-二甲氨基)乙酯(DMAEMA)等单体，得到了一系列结构明确的以PEO为主链的两亲性接枝共聚物：PEO-g-PS、PEO-g-PMA、PEO-g-tBA、和PEO-g-PDMAEMA，并由PEO-g-tBA通过选择性水解（三氟乙酸）得到双亲水性接枝共聚物PEO-g-PAA。其中，我们对由大分子引发剂Poly(EO-co-Gly)ATRP引发苯乙烯和丙烯酸甲酯这两种单体的ATRP聚合过程进行了动力学研究，结果证明聚合过程是可控的。在丙烯酸甲酯的聚合过程中，用乙腈作为溶剂时，其聚合反应比本体聚合体系有更好的可控性，共聚物产物的分子量分布也更窄，同时没有均聚物出现。用凝胶渗透色谱(GPC)、核磁共振(1H NMR)、红外光谱(FT-IR)、基质辅助激光解吸附电离飞行时间质谱(MALDI-TOF)等手段对中间产物及最终产物进行了详细地表征，证明了这种合成聚醚(PEO)为主链的接枝共聚物的方法是可行的，并且是成功的。
2. 在阴离子共聚EPEE单体和环氧乙烷(EO)单体的过程中，通过变换引发剂体系中的醇的结构(由原来的二元醇变成多元醇，如三羟甲基丙烷和季戊四醇)，合成了星形结构的共聚物，通过水解反应脱去保护基团后，再与2-溴异丁酰溴反应，得到链的侧端挂有很多2-溴异丁酸酯基的星形大分子引发剂，通过ATRP聚合机理引发苯乙烯聚合得到PEO为主链，PS为侧链的星形－接枝共聚物。用凝胶渗透色谱(GPC)、核磁共振(1H NMR)、红外光谱(FT-IR)、基质辅助激光解吸附电离飞行时间质谱(MALDI-TOF)等手段对中间产物及最终产物进行了详细地表征，证明了这种合成聚醚(PEO)为主链的星形－接枝共聚物的方法是可行的，并且是成功的。
关键词：接枝共聚物、星形－接枝，缩水甘油醚、1-乙氧基乙基-2,3-环氧丙醚、聚苯乙烯、聚丙烯酸甲酯、聚丙烯酸叔丁酯、聚甲基丙烯酸-2-(N,N-二甲基)乙酯、聚丙烯酸

Abstract
Molecular Design, Synthesis and Characterization of Novel Graft Copolymers with Polyether (PEO) as Main Chain
Recently, various of linear and non-linear copolymers were designed and prepared owing to development of synthetic technology, especially in the field of the controlled / “living” polymerization. Amphiphilic graft copolymers containing dydrophilic and hydrophobic chains have received much attention due to their unique structure, many morphologies in solution as well as their potential applications in chemistry, physics, biology, and so on. However, most of these amphiphilic copolymers are composed of hydrophobic main chain and hydrophilic side chains. The inversed architecture graft copolymers with hydrophilic main chain and hydrophobic side chains are scarcely reported because of the difficulties of synthesis. Here, an efficient and universal method is introduced to synthesize the well-defined graft copolymer, three-arm star and four-arm star graft copolymers of PEO as main chain. The essential work completed by us shows as follows:
1. A novel type of well-defined graft copolymer of poly(ethylene oxide) as main chain is successfully prepared by combination of anionic and atom transfer radical polymerization (ATRP). The glycidol is protected by ethyl vinyl ether first to form 2,3-epoxypropyl-1-ethoxyethyl ether (EPEE), then copolymerized with EO by initiation with the mixture of diphenylmethylpotassium and triethylene glycol to give the well-defined poly(EO-co-EPEE). The latter is hydrolyzed in the acidic conditions, then the recovered copolymer of EO and glycidol (Gly) with multi pending hydroxyls [(poly(EO-co-Gly)] is esterified with 2-bromoisobutyryl bromide to produce the ATRP macroinitiator with multi pending bromoisobutyryl groups [poly(EO-co-Gly)(ATRP)]. Subsequently, the latter initiates the polymerization of styrene (St), methacrylate (MA), tert-butyl acrylate (tBA) and 2-(dimethylamino)ethyl methacrylate (DMAEMA) respectively to form the corresponding amphiphilic graft copolymer PEO-g-PS, PEO-g-PMA, PEO-g-PtBA and PEO-g-PDMAEMA. The double hydrophilic graft copolymer PEO-g-PAA is acquired by the hydrolysis of the amphiphilic graft copolymer PEO-g-PtBA. The polymerization kinetic of styrene and methacrylate initiated by poly(EO-co-Gly)(ATRP) are investigated respectively and found that both are well controlled. The object products and intermediates are characterized by 1H NMR, MOLDI-TOF-MS, IR and GPC in detail. It is proved that this route suggested by us to prepare the graft copolymers with PEO as main chain copolymer is successful.
2. A novel type of star-graft copolymer with poly(ethylene oxide) as main chain is successfully prepared by combination of anionic and atom transfer radical polymerization (ATRP). Anionic copolymerized 2,3-epoxypropyl-1-ethoxyethyl ether (EPEE) then with EO by initiation of mixture of diphenylmethylpotassium and polyol [1,1,1-tris(hydroxymethyl)propane (TMP) or pentaerythritol] to give the well-defined three-arm star poly(EO-co-EPEE) and four-arm star poly(EO-co-EPEE). Both star copolymer precursors are hydrolyzed in the acidic conditions, then the corresponding recovered star copolymers of EO and glycidol (Gly) with multi pending hydroxyls [three-arm star poly(EO-co-Gly) and four-arm star poly(EO-co-Gly)] are esterified with 2-bromoisobutyryl bromide to produce the ATRP macroinitiator with multi pending bromoisobutyryl groups [three-arm star poly(EO-co-Gly)(ATRP) and four-arm star poly(EO-co-Gly)(ATRP)].Then the latter initiates the polymerization of styrene (St) to form the corresponding amphiphilic three-arm star PEO-g-PS and four-arm PEO-g-PS. The object products and intermediates are characterized by 1H NMR, MOLDI-TOF-MS, IR and GPC in detail. It is proved that this method to synthesize the graft copolymers with PEO as main chain copolymer is successful.
Key  words: graft copolymer, star-garft, glycidol, 2,3-epoxypropyl-1-ethoxyethyl ether (EPEE)，polystyrene(PS), polymethacrylate (PMA), poly( tert-butyl acrylate) (PtBA), poly[2-(dimethylamino) ethyl methacrylate] (PDMAEMA), poly(acrylic acid)