Thermosensitive star-shaped eight-arm poly-2-alkyl-2-oxazolines ( M = 21,000 g mol −1 ) was synthesized. The arms were gradient copolymers of 2-ethyl-2-oxazoline (EtOx) and 2-isopropyl-2-oxazoline (iPrOx). The more hydrophilic EtOx units prevailed near the calix[8]arene core. For comparison, model linear gradient copolymer ( M = 3800 g mol −1 ) was investigated. For both polymers, comonomer molar ratio was 1/1. The aqueous solutions of copolymers were studied by light scattering and turbidimetry. Self-organization of linear and star-shaped molecules in solution was different, but the phase separation temperatures for these copolymers coincided. In order to find out the influence of the distribution of EtOx and iPrOx units along the arms on the behavior of star-shaped polyalkyloxazolines, the behavior of investigated stars was compared with that for stars, whose arms was block copolymers poly-2-isopropyl-2-oxazoline and poly-2-ethyl-2-oxazoline. It was shown that the phase separation temperature for gradient copolymer solutions was higher than one for block copolymers.

中文翻译：

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2-乙基-2-恶唑啉和2-异丙基-2-恶唑啉的热敏星形和线性梯度共聚物水溶液中的自组织

合成了热敏星形八臂聚-2-烷基-2-恶唑啉（M = 21,000 g mol -1 ）。臂是 2-乙基-2-恶唑啉 (EtOx) 和 2-异丙基-2-恶唑啉 (iPrOx) 的梯度共聚物。更亲水的 EtOx 单元在杯 [8] 芳烃核附近占主导地位。为了比较，研究了模型线性梯度共聚物（M = 3800 g mol -1 ）。对于两种聚合物，共聚单体摩尔比为 1/1。通过光散射和浊度法研究了共聚物的水溶液。溶液中线性和星形分子的自组织不同，但这些共聚物的相分离温度一致。为了找出 EtOx 和 iPrOx 单元沿臂分布对星形聚烷基恶唑啉行为的影响，研究恒星的行为与星臂是嵌段共聚物聚-2-异丙基-2-恶唑啉和聚-2-乙基-2-恶唑啉的恒星的行为进行了比较。结果表明，梯度共聚物溶液的相分离温度高于嵌段共聚物的相分离温度。