Di- and triblock betaine copolymers composed of a sulfobetaine with a carboxy/phosphobetaine were synthesized by one-pot aqueous reversible addition-fragmentation chain transfer (RAFT) polymerization. The betaine methacrylate monomers were fully converted at each step by tuning the concentrations of the monomers, the chain transfer agent, and the initiator. AB-type diblocks poly(carboxybetaine methacrylate)-b-poly(sulfobetaine methacrylate) (PGLBT-b-PSPE) and poly(2-(methacryloyloxy)ethyl phosphorylcholine)-b-poly(sulfobetaine methacrylate) (PMPC-b-PSPE) were prepared to have identical unit numbers with different total molecular weights. Unlike homo-polysulfobetaine solutions or PGLBT-b-PSPEs in our previous report, the aqueous solutions of those diblock copolymers showed weak upper critical solution temperature (UCST) behavior, monitored by transmittance/dynamic light scattering. Even at the lowest temperature, the diblock chains remained in the unimer/aggregate polydisperse state, which is the intermediate stage prior to the emergence of monodisperse micelles. It is thought that the UCST behavior that originated from electrostatic attraction among PSPE motifs was interfered by temperature-inert motifs (PGLBT/PMPC) on the opposite side, having nearly the same unit number. The BAB-type triblock copolymer PSPE-b-PGLBT-b-PSPE with a 1:1:1 stoichiometry showed a clearer transmittance shift and size variation due to the increased ratio of PSPE at both chain ends. While the transmittance gradually decreased by cooling, larger aggregates (~ 700 nm) than those of diblocks (~ 180 nm) emerged with unimers. The small-large diffusive modes transformed into a monodisperse mode at much lower temperatures, which is assumed to be flower-like micelles consisting of PGLBT-loop coronas and PSPE core. However, another sample of 1:2:1 stoichiometry showed incomplete transition as diblocks having a similar AB ratio.

Graphical abstract

中文翻译：

---

双和三聚甜菜碱嵌段共聚物的一锅法合成及其温度响应溶液行为

由磺基甜菜碱与羧基/磷酸甜菜碱组成的二嵌段和三嵌段甜菜碱共聚物是通过一锅水性可逆加成-断裂链转移 (RAFT) 聚合反应合成的。通过调整单体、链转移剂和引发剂的浓度，甜菜碱甲基丙烯酸酯单体在每一步都完全转化。AB型二嵌段聚（羧基甜菜碱甲基丙烯酸酯） - b -聚（磺基甜菜碱甲基丙烯酸酯）（PGLBT- b -PSPE）和聚（2-（甲基丙烯酰氧基）乙基磷酸胆碱） - b -聚（磺基甜菜碱甲基丙烯酸酯）（PMPC- b -PSPE）制备具有相同单元数和不同总分子量的化合物。与均聚磺基甜菜碱溶液或 PGLBT- b 不同-PSPE 在我们之前的报告中，这些二嵌段共聚物的水溶液显示出较弱的上限临界溶解温度 (UCST) 行为，由透射率/动态光散射监测。即使在最低温度下，二嵌段链仍处于单聚体/聚集体多分散状态，这是单分散胶束出现之前的中间阶段。据认为，源自 PSPE 基序之间静电吸引力的 UCST 行为受到相对侧的温度惰性基序 (PGLBT/PMPC) 的干扰，具有几乎相同的单元数。BAB型三嵌段共聚物PSPE- b- PGLBT- b-具有 1:1:1 化学计量比的 PSPE 显示出更清晰的透射率偏移和尺寸变化，这是由于两个链端 PSPE 的比例增加。虽然透光率通过冷却逐渐降低，但与二聚体 (~ 180 nm) 相比，单体出现了更大的聚集体 (~ 700 nm)。小到大的扩散模式在低得多的温度下转变为单分散模式，假设它是由 PGLBT 环冠和 PSPE 核组成的花状胶束。然而，另一个 1:2:1 化学计量的样品显示不完全转变，因为二嵌段具有相似的 AB 比。

图形概要