A novel hyperbranched lower critical solution temperature (LCST) polymer with sharp temperature and CO₂‐responsive behaviors is presented in this study. The target polymer of hyperbranched poly(oligo(ethylene glycol) (HBPOEG) is constructed using POEG as the backbone and tertiary amines as branch points. Phase transition of HBPOEG in aqueous solution is investigated by heating and cooling the system; the results indicate that HBPOEG in aqueous solution has a concentration‐dependent phase transition behavior with excellent repeatability. Moreover, LCST of HBPOEG can be tuned by bubbling CO₂ into the solution, as the tertiary amines can be protonated and the solubility of the polymer would increase by bubbling CO₂ into the system, leading to an increase of LCST of the polymer. Further bubbling N₂ to remove CO₂ can reversibly turn back the LCST to its original value. This backbone‐based hyperbranched LCST polymer with both CO₂ and temperature responsiveness can be applied in application areas like drug delivery, gene transfection, functional coatings, etc.

中文翻译：

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具有热响应和CO2响应主干的LCST型超支化聚（乙二醇）

这项研究提出了一种新型的超支化低临界溶液温度（LCST）聚合物，该聚合物具有尖锐的温度和CO ₂响应行为。以POEG为骨架，叔胺为分支点，构建了超支化聚（乙二醇）（HBPOEG）的目标聚合物，通过加热和冷却研究了HBPOEG在水溶液中的相变；结果表明，HBPOEG在水溶液中具有与浓度有关的相变行为，并具有出色的重复性；此外，可以通过将CO ₂鼓入溶液来调节HBPOEG的LCST ，因为叔胺可以被质子化，并且通过鼓泡CO ₂可以增加聚合物的溶解度进入系统，导致聚合物的LCST增加。进一步鼓泡N ₂以除去CO ₂可以可逆地将LCST恢复到其原始值。这种具有CO ₂和温度响应性的基于主链的超支链LCST聚合物可应用于药物递送，基因转染，功能性涂层等应用领域。