【作者】 肖安国；

【导师】 王立；

【作者基本信息】 浙江大学 ， 高分子化学与物理， 2009， 博士

【摘要】 在乙烯聚合催化体系α-二亚胺镍配合物/MAO中加入ZnEt₂,通过链行走与链转移的竞争反应来控制所得聚合物的支化度及支链结构,合成了5种含有不同支化度的聚乙烯。聚合物的支化度从Ni/MAO/Zn=1/1000/0时的140个支链/1000个碳降低到Ni/MAO/Zn=1/1000/200时的97.0个支链/1000个碳,同时甲基的含量从88.5%升高到93.7%。通过改变催化体系中助催化剂的含量,合成了4种含有不同支化度的聚乙烯。结果表明,ZnEt₂对聚合物的支化度有较好的调控作用。同时ZnEt₂能显著提高催化剂活性,可能的原因是其能促进催化剂的再活化。仅从乙烯单体出发,利用α-二亚胺镍配合物/乙撑桥二氯茚锆/MAO/ZnEt₂体系催化乙烯聚合,合成了7种不同微结构的聚乙烯。所得聚合物的微结构分析表明,产物是线型-超支化多嵌段聚乙烯。其可能的聚合机理为:α-二亚胺镍配合物/MAO催化乙烯聚合,通过链行走生成超支化聚乙烯链段;乙撑桥二氯茚锆/MAO催化乙烯聚合生成线型聚乙烯链段;在链转移剂ZnEt₂协助下,通过链穿梭聚合制得了线型-超支化多嵌段聚乙烯。同时利用EPR研究了16种不同的催化体系,发现较高的MAO用量不利于乙烯聚合,其原因是α-二亚胺镍配合物能被MAO还原成无聚合活性的Ni（Ⅰ）物种。通过配位聚合和ATRP,合成了6种不同分子量的超支化.星型聚[乙烯-co-丙烯酸-2-（2-溴-异丁酰氧基）乙酯]-g-聚甲基丙烯酸特丁酯[P（E-co-BIEA）-g-P^tB_uMA]。经水解所得聚合物,制得了超支化-星型聚[乙烯-co-丙烯酸-2-（2-溴-异丁酰氧基）乙酯]-g-聚甲基丙烯酸[P（E-co-BIEA）-g-PMAA]。P（E-co-BIEA）-g-PMAA在水溶液中能形成单分子胶束,通过调节聚合物溶液的pH值,发现单分子胶束粒径在30～80nm间可逆变化,单分子胶束对pH值有很好的响应性。采用配位聚合和ATRP,合成了3种含有不同的聚丙烯酸二茂铁甲酰氧基乙酯链长的超支化.星型聚[乙烯-co-丙烯酸-2-（2-溴-异丁酰氧基）乙酯]-g-聚丙烯酸-二茂铁甲酰氧基乙酯[P（E-co-BIEA）-g-PFcEA];采用直接共聚法,合成了4种具有不同丙烯酸二茂铁甲酰氧基乙酯含量的超支化聚（乙烯-co-丙烯酸二茂铁甲酰氧基乙酯）[P（E-co-FcEA）]。通过CV和UV-Vis研究表明,P（E-co-BIEA）-g-PFcEA是一种理想的阴离子识别受体。另外,以P（E-co-FcEA）为前驱体,经自催化制得系列碳纳米材料。通过配位聚合、ATRP和开环聚合,合成了新型超支化-星型聚[乙烯-co-丙烯酸-2-（2-溴-异丁酰氧基）乙酯]-g-聚丙烯酸羟乙酯[P（E-co-BIEA）-g-PHEA]和超支化-星型聚[乙烯-co-丙烯酸-2-（2-溴-异丁酰氧基）乙酯]-g-聚丙烯酸羟乙酯-g-聚己内酯[P（E-CO-BIEA）-g-PHEA-g-PCL]。通过P（E-co-BIEA）-g-PHEA-g-PCL的DSC和偏光显微研究,并与聚己内酯比较,发现这类聚合物生成的结晶颗粒尺寸较小,且聚合物在乙醇溶液中能形成粒径在50～200nm之间的胶束。更多还原

【Abstract】 Polyethylenes（5 kinds） with different branching density and composition were synthesized usingα-diimine nickel complex/MAO catalyst system in the presence of ZnEt₂.In polymerization process,the branching density and composition of polyethylene were controlled by the competitive reaction of chain walking and chain transfer.Polyethylene with 140.0 branches per 1000 carbons was produced when Ni/Al/Zn =1/1000/0,and among these branches,88.5%was methyl.However,the branching density of the polyethylene prepared when Ni/Al/Zn =1/1000/200 decreased to 97.0 branches per 1000 carbons and the methyl percentage increased to 93.7%.By varying the MAO concentration inα-diimine nickel complex/MAO,polyethylenes（4 kinds） with different branching density were obtained.The results indicated that ZnEt₂ showed high capability for adjusting the branching density of resultant polyethylene.Furthermore,α-diirnine nickel complex/MAO/ZnEt₂ afforded higher activity thanα-diimine nickel complex/MAO for ethylene polymerization and it was possible that ZnEt₂ facilitated the reactivation ofα-diimine nickel complex.Seven samples of polyethylenes with different microstructures were produced usingα-diimine nickel complex/ansa-ethylenebis-（1-η⁵-indenyl） zirconium dichloride/MAO/ZnEt₂ alone from ethylene and the microstructures of resultant polymers indicated that the novel linear -hyperbranched multiblock polyethylene was successfully obtained.The possible mechanism was thatα-diimine nickel complex/MAO produced chain with hyperbranched architecture via chain walking,while ansa-ethylenebis-（1-η⁵-indenyl） zirconium dichloride/MAO afforded linear chain. Then chain transfer agent（ZnEt₂） facilitated chains shuttling between two kinds of active metal centres,as a result,the novel multiblock polyethylene was synthesized by chain shuttling polymerization.In addition,EPR signals of 16 types of the catalyst system suggested that excess MAO might undermine the activity of catalyst system,the possible reason was thatα-diimine nickel complex was distinctly reduced into Ni（I） by MAO and Ni（I） showed no activity in ethylene polymerization.Six kinds of hyperbranched-star poly[ethylene-co-2-（2-bromoisobutyryloxy） ethyl acrylate]- g-poly（tert-butyl methacrylate）[P（E-co-BIEA）-g-P^tB_uMA]with different molecular weight were prepared via the combining strategy of coordination polymerization and atom transfer radical polymerization,then cleaving P（E-co-BIEA）-g-P^tB_uMA afforded poly[ethylene-co-2-（2-bromoiso butyryloxy） ethyl acrylate]-g-poly（methacrylic acid）[P（E-co-BIEA）-g-PMAA].Mono-molecular micelles evidently formed in the P（E-co-BIEA）-g-PMAA solution using water as solvent and the reversible variation of the micelle size in the range of 30～80nm was exclusively attributed to variation of pH value of the polymer solution.Three kinds of hyperbranched-star poly[ethylene-co-2-（2-bromoisobutyryloxy） ethyl acrylate] -g-poly（ferrocenyloxy ethyl acrylate）（[P（E-co-BIEA）-g-PFcEA]） with different PFcEA chain lengths were prepared via coordination polymerization and atom transfer radical polymerization. In addition,four kinds of hyperbranched poly（ethylene-co-ferrocenyloxy ethyl acrylate）[P（E-co-FcEA）] containing different FcEA content were synthesized with direct copolymerization of ethylene with FcEA.The investigation of P（E-co-BIEA）-g-PFcEA in CH₂Cl₂ via CV and UV-Vis indicated that P（E-co-BIEA）-g-PFcEA in CH2C12 was an appropriate receptor for anion recognition.Furthermore,a series of carbon nanomaterials were successfully synthesized with P（E-co-FcEA） as precursor via self-catalysis.The novel hyperbranched-star poly[ethylene-co-2-（2-bromoisobutyryloxy） ethyl acrylate]-g -poly（hydroxyl ethylacrylate）[P（E-co-BIEA）-g-PHEA]and poly[ethylene-co-2-（2-bromoiso butyryloxy） ethyl acrylate]-g-poly（hydroxyl ethylacrylate）-g-poly（ε-caprolactone）[P（E-co-BIEA） -g-PHEA-g-PCL]were successfully synthesized via coordination polymerization,atom transfer radical polymerization and ring-opening polymerization.The DSC curves and the polarized optical images of P（E-co-BIEA）-g-PHEA-g-PCL indicated that the crystal size of P（E-co-BIEA） -g-PHEA-g-PCL was much smaller than that of poly（ε-caprolactone）.Furthermore,the rnicelles with the size of 50～200nm were effectively obtained from P（E-co-BIEA）-g-PHEA -g-PCL solution using ethanol as solvent.更多还原