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Control of the temperature responsiveness of poly(N-isopropylacrylamide-co-2-hydroxyethyl methacrylate) copolymer using ultrasonic irradiation
Ultrasonics Sonochemistry ( IF 8.4 ) Pub Date : 2021-09-13 , DOI: 10.1016/j.ultsonch.2021.105752
Masaki Kubo 1 , Masato Higuchi 1 , Tomoyuki Koshimura 1 , Eita Shoji 2 , Takao Tsukada 1
Affiliation  

Poly(N-isopropylacrylamide-co-2-hydroxyethyl methacrylate) (poly(NIPAM-co-HEMA)) is a temperature-responsive copolymer that is expected to be applicable as an advanced functional polymeric material in various fields. In this study, a novel method was developed to control the responsive temperature of poly(NIPAM-co-HEMA) using an ultrasonic polymerization technique. Initially, the behavior of the reaction was investigated using NIPAM and HEMA monomers under ultrasonic irradiation. A high ultrasonic power was found to produce a high reaction rate and low number average molecular weight of the copolymer. The polydispersity of the synthesized copolymer was approximately 1.5 for all ultrasonic powers examined. In the early stage of the reaction, the molar fraction of NIPAM in the copolymer was lower than the initial molar fraction of the monomers. It was concluded that ultrasonic irradiation affected the initiation reaction and polymer degradation, but did not affect the propagation reaction. Furthermore, the effect of the ultrasonic irradiation conditions on the temperature responsiveness of the copolymer was investigated. The lower critical solution temperature (LCST) of the copolymer was found to increase with increasing ultrasonic irradiation time. In addition, in the early stages of the reaction, the measured values of the LCST were higher than the estimated values using copolymer composition. This can be attributed to some parts of the copolymer chain possessing a higher NIPAM fraction than the overall fraction due to different reactivities of the monomers and terminated radicals. This hypothesis was indirectly verified by the synthesis of a block copolymer from the PNIPAM homopolymer and HEMA monomer.



中文翻译:

使用超声波辐照控制聚(N-异丙基丙烯酰胺-co-2-羟乙基甲基丙烯酸酯)共聚物的温度响应性

聚(Ñ -isopropylacrylamide--2-羟基乙基甲基丙烯酸酯)(聚(NIPAM--HEMA))]是预期可应用于作为在各种领域中的高级功能性聚合物材料的温度响应型共聚物。在这项研究中,开发了一种新方法来控制聚(NIPAM- co-HEMA) 使用超声波聚合技术。最初,在超声辐照下使用 NIPAM 和 HEMA 单体研究了反应行为。发现高超声功率产生共聚物的高反应速率和低数均分子量。对于所有检查的超声功率,合成共聚物的多分散性约为 1.5。在反应初期,共聚物中 NIPAM 的摩尔分数低于单体的初始摩尔分数。结论是超声辐照影响引发反应和聚合物降解,但不影响增长反应。此外,研究了超声辐照条件对共聚物温度响应性的影响。发现共聚物的较低临界溶解温度 (LCST) 随超声辐照时间的增加而增加。此外,在反应的早期阶段,LCST 的测量值高于使用共聚物组合物的估计值。这可归因于由于单体和封端自由基的不同反应性,共聚物链的某些部分具有比整体分数更高的 NIPAM 分数。这一假设通过由 PNIPAM 均聚物和 HEMA 单体合成嵌段共聚物间接得到证实。这可归因于由于单体和封端自由基的不同反应性,共聚物链的某些部分具有比整体分数更高的 NIPAM 分数。这一假设通过由 PNIPAM 均聚物和 HEMA 单体合成嵌段共聚物间接得到证实。这可归因于由于单体和封端自由基的不同反应性,共聚物链的某些部分具有比整体分数更高的 NIPAM 分数。这一假设通过由 PNIPAM 均聚物和 HEMA 单体合成嵌段共聚物间接得到证实。

更新日期:2021-09-23
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