硅宾/有机铝的Lewis酸碱对体系及其丙烯酸酯聚合的引发性能

Silylene/Organoaluminum Lewis Pair System and the Initiation Property for Polymerization of(Meth)acrylates

研究了硅宾/有机铝组成的Lewis酸碱对(LP)体系引发丙烯酸酯类单体聚合的性能,合成了4种硅宾:L(Ph_(2)P)Si(Si-1,L=Ph C(NtBu)_(2))、L[4-MeC_(6)H_(4)(Ph_(2)P)N]Si(Si-2)、L[2,6-iPr_(2)C_(6)H_(3)(1,5-C_(8)H_(14)B)N]Si(Si-3)、L(LSi)Si(Si-4)和6种有机铝:Al(C_(6)F_(5))_(3)、AlMe(BHT)_(2)、AliBu(BHT)_(2)、AliBu_(2)(BHT)、AliBu(BHT*)_(2)、AliBu_(2)(BHT*)(BHT=2,6-tBu_(2)-4-MeC_(6)H_(2)O,BHT*=2,4,6-tBu_(3)C_(6)H_(2)O).Si-1/有机铝和Si-4/有机铝LP体系均能引发甲基丙烯酸甲酯(MMA)完全聚合,活性转换频率(TOF)值为50~400 h^(-1),产出PMMA的分子量Mn82000~271000和分子量分布D1.11~1.81.Si-2/有机铝和Si-3/有机铝LP体系没有活性.Si-1/Al(C6F5)3体系对丙烯酸正丁酯(nBA)、丙烯酸-2-乙基己基酯(EHA)的活性较差,但是Si-1/其它有机铝都能高效引发nBA和EHA完全聚合.对nBA,TOF值4.8×10^(4)~14.4×10^(4)h^(-1),产出Pn BA的Mn100000~179000和D1.08~1.59;对EHA,TOF值至14.4×10^(4)~36.0×10^(4)h^(-1),生成PEHA的Mn 81000~240000以及?1.12~1.95.研究了聚合反应的可能机理.

The initiation polymerization property of(meth)acrylates by using the silylene/organoaluminum Lewis pair(LP)system is studied.Four silylenes L(Ph_(2)P)Si(Si-1,L=PhC(Nt Bu)_(2)),L[4-MeC_(6)H_(4)(Ph_(2)BHT*=2,4,6-tBu_(3)C_(6)H_(2)O)P)N]Si(Si-2),L[2,6-i Pr_(2)C_(6)H_(3)(1,5-C_(8)H_(14)B)N]Si(Si-3),and L(LSi)Si(Si-4)as the Lewis base(LB)were synthesized,together with six organoaluminums Al(C_(6)F_(5))_(3),AlMe(BHT)_(2),Ali Bu(BHT)_(2),Ali Bu_(2)(BHT),Ali Bu(BHT*)_(2),and Ali Bu2(BHT*)(BHT=2,6-t Bu_(2)-4-MeC_(6)H_(2)O and BHT*=2,4,6-t Bu_(3)C_(6)H_(2)O)as the Lewis acid(LA).Si-1/organoaluminum and Si-4/organoaluminum LP systems all enable to initiate the complete methacrylate(MMA)polymerization,achieving turnover of frequency(TOF)activities in the range of 50~400 h^(-1)with PMMA Mn of 82000~271000 andĐof 1.11~1.81.Neither Si-2/organoaluminum or Si-3/organoaluminum was active.The Si-1/Al(C6F5)3 displayed poor reactivity on n-butyl acrylate(nBA)and 2-ethylhexyl acrylate(EHA).However,the Si-1/other organoaluminums exhibited both complete nBA and EHA polymerizations.For nBA,the TOFs were obtained by 4.8×10^(4)~14.4×10^(4)h^(-1),in which the PnBAs were produced with Mn 100000~179000 andĐ1.08~1.59.For EHA,the TOFs were up to 14.4×10^(4)~36.0×10^(4)h^(-1),where the PEHAs were yielded with Mn 81000~240000 andĐ1.12~1.95.The probable polymerization mechanism with the silylene/organoaluminum LP system is investigated.