Chain shuttling copolymerisation (CSP) is a synthetic strategy allowing the one-pot, one-step formation of block copolymers. Initially developed in the frame of coordinative polymerisation of olefins and conjugated dienes, it was recently transferred to the ring-opening polymerisation of cyclic esters. In this contribution, we report six new catalytic systems able to perform the chain shuttling copolymerisation of L-lactide (L-LA) with ε-caprolactone (ε-CL) and to tune the thermal properties of the resulting copolymers. They are based on amino(bis)phenolate supported aluminium complexes bearing different pendant donor arms ((Al(O₂N^L)OBn), L = NEt₂ (2a), NBn₂ (2b), Py (2c), Mor (2d)). A Mannich reaction allowed the ligands synthesis. The two new alkoxide complexes 2a and 2b were obtained by reaction of the protonated ligands with trimethylaluminium followed by benzyl alcohol in reasonable yield, as well as two already described compounds 2c and 2d. Initially assessed as catalysts for L-LA and ε-CL homopolymerisations and statistical copolymerisation, the aluminium compound bearing pyridine as a donor arm (2c) resulted in a high selectivity toward lactide. 2c together with yttrium and aluminium alkoxides, also known for their selectivity for lactide, were successfully assessed for the chain shuttling copolymerisation of L-LA with ε-CL in combination with the three other amino(bis)phenolate supported aluminium complexes that showed a higher selectivity toward ε-CL. Chain shuttling copolymerization via transalkoxylation between two different metals, Y and Al, is achieved for the first time, therefore extending the range and scope of cyclic esters CSP. Such an alteration of the nature of the catalysts allowed fine tuning of the thermal properties of the chain shuttled copolymer, as shown by a variation of the glass transition temperature (T_g) of the soft block over ca. 25 °C without changing the catalysts ratio and feed of the reaction.

中文翻译：

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通过催化剂选择调节 L-丙交酯/ε-己内酯链穿梭共聚物的热性能


链穿梭共聚（CSP）是一种合成策略，允许一锅一步形成嵌段共聚物。最初是在烯烃和共轭二烯的配位聚合框架中开发的，最近被转移到环酯的开环聚合。在这篇文章中，我们报告了六种新的催化系统，能够进行L-丙交酯 ( L -LA) 与 ε-己内酯 (ε-CL) 的链穿梭共聚，并调节所得共聚物的热性能。它们基于氨基（双）酚盐支撑的铝配合物，带有不同的侧链供体臂 ((Al(O ₂ N ^L )OBn)、L = NEt ₂ ( 2a )、NBn ₂ ( 2b )、Py ( 2c )、Mor ( 2d ))。曼尼希反应允许配体合成。通过质子化配体与三甲基铝反应，然后与苯甲醇反应，以合理的产率获得两种新的醇盐配合物2a和2b ，以及两种已经描述的化合物2c和2d 。最初被评估为L -LA 和 ε-CL 均聚和统计共聚的催化剂，带有吡啶作为供体臂的铝化合物 ( 2c ) 对丙交酯具有高选择性。 2c与钇和铝醇盐（也因其对丙交酯的选择性而闻名）一起成功评估了L -LA 与 ε-CL 与其他三种氨基（双）酚盐支持的铝配合物的链穿梭共聚，显示出更高的对 ε-CL 的选择性。首次实现了两种不同金属Y和Al之间通过烷氧基转移的链穿梭共聚，从而扩展了环酯CSP的范围和范围。催化剂性质的这种改变允许对链穿梭共聚物的热性能进行微调，如软嵌段的玻璃化转变温度（ T _g ）在约 100 ℃范围内的变化所示。 25℃，不改变催化剂比例和反应进料。