We report that the fractions of “bonded” or “unbonded” monomers at a filler interface dictate the composition dependence of the glass transition temperatures (T_g) of polyhedral oligomeric silsesquioxane (POSS)-containing nanocomposites. T_g is arguably the single most important material property; however, predicting T_g in nanocomposites is often challenging because of confounding interfacial effects. To this end, we design a model nanocomposite to systematically study T_g of nanocomposites by leveraging the “all-interfacial” nature of ultrasmall POSS fillers loaded into random copolymers of styrene and 2-vinylpyridine (2VP). The amine-functionalized POSS forms hydrogen bonds only with 2VP, which behaves as a “bonded” monomer. The influence of copolymer composition and POSS loading on the T_g of this model composite is successfully explained by a Fox equation framework. This model also captures the T_g increase of other POSS-based polymer composites and potentially directs the future design of nanocomposite materials with tailored T_g.

中文翻译：

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合理化非晶聚合物/POSS复合材料中玻璃化转变温度的成分依赖性

我们报告说，填料界面处“键合”或“未键合”单体的比例决定了含多面体低聚倍半硅氧烷 (POSS) 纳米复合材料_{的玻璃化转变温度 (Tg} )的组成依赖性。T _g可以说是最重要的材料特性。然而，由于混杂的界面效应，预测纳米复合材料中的T _g通常具有挑战性。为此，我们设计了一个模型纳米复合材料来系统地研究T _g通过利用加载到苯乙烯和 2-乙烯基吡啶 (2VP) 的无规共聚物中的超小 POSS 填料的“全界面”性质来制备纳米复合材料。胺官能化的 POSS 仅与 2VP 形成氢键，其表现为“键合”单体。Fox方程框架成功地解释了共聚物组成和POSS负载对该模型复合材料的T _{g的影响。}该模型还捕捉了其他基于 POSS 的聚合物复合材料的T _g增加，并可能指导未来设计具有定制T _g的纳米复合材料。