Thermoresponsivity, Micelle Structure, and Thermal-Induced Structural Transition of an Amphiphilic Block Copolymer Tuned by Terminal Multiple H-Bonding Units.,Langmuir

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Thermoresponsivity, Micelle Structure, and Thermal-Induced Structural Transition of an Amphiphilic Block Copolymer Tuned by Terminal Multiple H-Bonding Units.
Langmuir ( IF 3.7 ) Pub Date : 2020-01-17 , DOI: 10.1021/acs.langmuir.9b03290
Xiaohua Chang ₁ , Chen Wang ₂ , Guorong Shan ₁ , Yongzhong Bao ₁ , Pengju Pan ₁

Affiliation

Constructing noncovalent interactions has been a benign method to tune the stimuli responsivity and assembled structure of polymers in solution; this is essential for controlling the functions and properties of stimuli-responsive materials. Herein, we demonstrate a novel supramolecular strategy to manipulate the cloud point (Tcp) and assembled structure of thermoresponsive polymers in solution by using H-bonding interactions. We use poly(lactide-co-glycolide)-b-poly(ethylene glycol)-b- poly(lactide-co-glycolide) (PLGA-PEG-PLGA) as a model thermoresponsive polymer and functionalize its chain terminals by the self-complementary quadruple H-bonding motif, 2-ureido-4[1H]-pyrimidinone (UPy). UPy end functionalization and increasing PLGA block length decrease the Tcp of copolymer. Both UPy- and nonfunctionalized copolymers form the spherical micelles at low temperature. They undergo the intermicellar aggregation and form large compound micelles during heating; this thermally induced structural transition causes the presence of Tcp. Due to the UPy-UPy H-bonding interactions, UPy end functionalization leads to more copolymer chains to associate in one micelle, thus, enhancing the hydrodynamic, gyration radii, core size, as well as the packing density of PLGA in micelle core and grafting density of PEG on core-shell interface. The decreased Tcp of UPy-functionalized copolymer stemmed from the stronger intermicellar attractions at high temperature. Furthermore, UPy-functionalized copolymers exhibit higher drug loading content, slower drug release rate, and better separation efficiency in removing the hydrophobic substances from water than PLGA-PEG-PLGA precursors.

中文翻译：

通过末端多个H键合单元调节的两亲嵌段共聚物的热响应性，胶束结构和热诱导的结构转变。

构建非共价相互作用一直是调节溶液中聚合物的刺激响应性和组装结构的良性方法。这对于控制刺激反应材料的功能和特性至关重要。在这里，我们演示了一种新颖的超分子策略，通过使用H键相互作用来控制溶液中的热敏聚合物的浊点（Tcp）和组装结构。我们使用聚（丙交酯-共-乙交酯）-b-聚（乙二醇）-b-聚（丙交酯-共乙交酯）（PLGA-PEG-PLGA）作为模型热敏聚合物，并通过自聚合功能化其链端互补四重H键基序，2-ureido-4 [1H]-嘧啶酮（UPy）。UPy末端官能化和增加PLGA嵌段长度会降低共聚物的Tcp。UPy和非官能化共聚物均在低温下形成球形胶束。它们在加热过程中发生胶束间的聚集并形成大的复合胶束。这种热诱导的结构转变导致Tcp的存在。由于UPy-UPy H键相互作用，UPy末端官能化导致更多的共聚物链在一个胶束中缔合，从而提高了胶束芯和接枝PLGA的流体力学，回转半径，芯尺寸以及堆积密度。核-壳界面上PEG的密度 UPy官能化共聚物的Tcp降低是由于高温下较强的胶束间吸引力所致。此外，UPy官能化的共聚物具有较高的载药量，较慢的药物释放速率，

更新日期：2020-01-17

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