Controlled bulk polymerization of l-lactide and lactones by dual activation with organo-catalytic systems
作者:Joji Kadota、Dražen Pavlović、Hiroshi Hirano、Akinori Okada、Yasuyuki Agari、Brigitte Bibal、Alain Deffieux、Frédéric Peruch
DOI:10.1039/c4ra01239a
日期:——
The acid–base catalytic system based on N,N-dimethyl-4-aminopyridine (DMAP) and a protic acid that has already been revealed to be efficient for the ring-opening polymerization (ROP) of L-lactide in solution at room temperature was tested for the same polymerization in bulk at 100 °C. As observed in solution, the presence of the DMAP·HX (X = Cl, CH3SO3, CF3SO3) salt enhanced yields. Linear and star-like polylactides with 3 and 4 branches were prepared. Polylactides were thus easily prepared reaching high molar masses (up to 75 000 g mol−1 for linear PLLA and 140 000 g mol−1 for star-like PLLA) with good control in less than 1 h. In all cases, the appearance of transesterification reactions was shown to occur only at very high yield. The ROP of lactones (ε-caprolactone and δ-valerolactone) was also investigated with the same catalytic systems in bulk conditions. In contrast to lactide polymerization, only the DMAP/DMAP·HOTf allowed lactone polymerization with a slower rate. However, the control over the molar masses remained very good. Block copolymers were also synthesized.
基于 N,N-二甲基-4-氨基吡啶(DMAP)和一种原酸的酸碱催化体系已被证明可在室温下有效地进行 L-内酰胺在溶液中的开环聚合(ROP)反应。正如在溶液中观察到的那样,DMAP-HX(X = Cl、CH3SO3、CF3SO3)盐的存在提高了产量。制备出了具有 3 个和 4 个分支的线型和星型聚乳酸。因此,制备高摩尔质量的聚乳酸(线型聚乳酸高达 75 000 g mol-1,星型聚乳酸高达 140 000 g mol-1)非常容易,且在 1 小时内就能很好地控制。我们还使用相同的催化体系在大量条件下研究了内酯(ε-己内酯和 δ-戊内酯)的 ROP。与内酯聚合相比,只有 DMAP/DMAP-HOTf 能以较慢的速度进行内酯聚合。不过,对摩尔质量的控制仍然很好。此外,还合成了嵌段共聚物。