Thermoresponsive polymers have attracted much scientific attention due to their capacity for temperature-driven hydrogel formation. For biomedical applications, such as drug delivery, this transition should be tuned below body temperature to facilitate controlled and targeted drug release. We have recently developed a thermoresponsive polymer that forms gel at low concentrations (2 w/w%) in aqueous media and offers a cost-effective alternative to thermoresponsive systems currently being applied in clinics. This polymer is an ABC triblock terpolymer, where A, B, and C correspond to oligo(ethylene glycol) methyl ether methacrylate with average 300 g mol (OEGMA300), -butyl methacrylate (BuMA), and di(ethylene glycol) methyl ether methacrylate (DEGMA). To investigate the self-assembly and the gelation mechanism in diluted solutions, we used small-angle neutron scattering (SANS) on 1 w/w% (below the gelation concentration) and 5 w/w% solutions (above the gelation concentration). As a comparison, we also investigated the solutions of the most studied thermoresponsive polymer, namely, Pluronic F127, an ABA triblock bipolymer made of ethylene glycol (A) and propylene glycol (B) blocks. SANS revealed that the synthesised polymer forms elliptical cylinders, whose length increases significantly with temperature. In contrast, Pluronic F127 solutions form core-shell spherical micelles, which slightly elongate with temperature. Transmission electron microscopy images support the SANS findings, with tubular/worm structures being present. Variable-temperature circular dichroism (CD) and proton nuclear magnetic resonance (H NMR) spectroscopy experiments reveal insights on the tacticity, structural changes, and molecular origin of the self-assembly.

中文翻译：

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驱动热凝胶化的 ABC 嵌段共聚物胶束：散射、成像和光谱

热响应聚合物由于其温度驱动水凝胶形成的能力而引起了科学界的广泛关注。对于生物医学应用，例如药物输送，这种转变应该调整到低于体温，以促进受控和有针对性的药物释放。我们最近开发了一种热响应聚合物，可在水介质中以低浓度 (2 w/w%) 形成凝胶，为目前临床应用的热响应系统提供了一种经济有效的替代方案。该聚合物是 ABC 三嵌段三元共聚物，其中 A、B 和 C 对应于平均 300 g mol 的低聚乙二醇甲醚甲基丙烯酸酯 (OEGMA300)、甲基丙烯酸丁酯 (BuMA) 和二乙二醇甲醚甲基丙烯酸酯（德格玛）。为了研究稀释溶液中的自组装和凝胶机制，我们在 1 w/w%（低于凝胶浓度）和 5 w/w% 溶液（高于凝胶浓度）上使用小角中子散射 (SANS)。作为比较，我们还研究了研究最多的热响应聚合物的溶液，即 Pluronic F127，这是一种由乙二醇 (A) 和丙二醇 (B) 嵌段组成的 ABA 三嵌段二元聚合物。 SANS表明，合成的聚合物形成椭圆柱，其长度随着温度的升高而显着增加。相比之下，Pluronic F127 溶液形成核壳球形胶束，随着温度的升高而略微伸长。透射电子显微镜图像支持 SANS 的发现，存在管状/蠕虫结构。变温圆二色性（CD）和质子核磁共振（1H NMR）光谱实验揭示了自组装的立构规整度、结构变化和分子起源。