State Key Laboratory of Separation Membranes and Membrane Processes, School of Chemistry, Tiangong University, Tianjin, 300387, P. R. China.
Macromol Rapid Commun. 2023 Apr;44(8):e2300005. doi: 10.1002/marc.202300005. Epub 2023 Feb 15.
A mild organocatalyzed living radical polymerization method is studied for high molecular weight polymers (HMWPs), yielding low-dispersity linear and star polymers (Đ = M /M = 1.03-1.28) up to M = 3.9 × 10 and monomer conversion = 80%, where M and M are the number- and weight-average molecular weights, respectively. Even at high degrees of polymerization (DPs > 2000), this technique still features excellent control over molecular weights and Đ values, indicating the living character. The macroinitiators prepared at DP = 2000 are subsequently used for block polymerizations at high DPs (>2000) with functional methacrylates, yielding linear A-B diblock, linear B-A-B triblock, and 3-arm star A-B diblock copolymers, suggesting the excellent block efficiency of macroinitiators synthesized at a high DP value (=2000). This mild organocatalyzed living radical polymerization technique can enhance the livingness of propagation radicals and kinetic chain length at high monomer conversions for monomers with moderate propagation rate coefficients (k s), reduce the persistent radical effect as much as possible, and hence enable HMWPs without the presence of metal catalyst, exogenous initiator, or harsh equipment. The obtained amphiphilic block copolymers present unique microphase separation behavior, and hold great potential in advanced materials applications, for example, thermosensitive nanocarriers.
一种温和的有机催化活性自由基聚合方法被用于合成高分子量聚合物（HMWPs），得到低分散的线性和星形聚合物（Đ = M/Mn = 1.03-1.28），分子量高达 3.9×10，单体转化率达 80%，其中 M 和 Mn 分别为数均分子量和重均分子量。即使在高聚合度（DP > 2000）下，该技术仍然对分子量和 Đ 值具有极好的控制能力，表明具有活性聚合的特征。在 DP = 2000 时制备的大分子引发剂随后用于在高 DP（> 2000）下与功能性甲基丙烯酸酯进行嵌段聚合，得到线性 A-B 两嵌段、线性 B-A-B 三嵌段和 3 臂星形 A-B 两嵌段共聚物，表明在高 DP 值（= 2000）下合成的大分子引发剂具有良好的嵌段效率。这种温和的有机催化活性自由基聚合技术可以提高在具有中等增长速率系数（ks）的单体的高单体转化率下的增长自由基和动力学链长的活性，尽可能减少持久自由基效应，因此可以在没有金属催化剂、外加引发剂或苛刻设备的情况下得到高分子量聚合物。所得的两亲性嵌段共聚物表现出独特的微相分离行为，在先进材料应用方面具有巨大的潜力，例如热敏性纳米载体。
