Intermolecular hydrogen bonds (inter-HBs) typically act as transient cross-linkers and can enhance the intermolecular interactions. Herein, we report a counterintuitive scenario that interchain constraints of polyacrylates are alleviated by adding hindered phenols capable of forming strong inter-HB interactions with the host polymer, even if a small molecule-bridged inter-HB network apparently increases the glass transition temperature (T_g) of the hybrids. The less-constrained segmental dynamics is confirmed enthalpically by the enhanced dynamic homogeneity (i.e., an increase in nonlinearity parameter x and stretching exponential parameter β) of α-relaxation together with a remarkable increase in the physical aging rate at (T_g – 10) K. Further results clarified that x and β values are primarily governed by the strength of inter-HB interactions (Δυ_i), and a stronger Δυ_i results in a larger x or β value. The present work provides solid experimental evidence and new molecular-level insights for the less-constrained segmental dynamics in such HB-driven hybrids in terms of the balanced flexibility between side groups and the backbone, the reduction of energy barriers hindering the cooperative motions, and the alleviation of long-chain connectivity.

中文翻译：

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氢键诱导减轻与小分子混合的丙烯酸聚合物的拓扑约束

分子间氢键（inter-HBs）通常充当瞬时交联剂，可以增强分子间相互作用。在此，我们报告了一种违反直觉的情况，即通过添加能够与主体聚合物形成强HB间相互作用的受阻酚来减轻聚丙烯酸酯的链间约束，即使小分子桥接HB间网络明显提高了玻璃化转变温度（T _g ) 的杂种。 α-弛豫的动​​态均匀性增强（即非线性参数x和拉伸指数参数 β 的增加）以及 ( T _g – 10)处物理老化速率的显着增加，从焓上证实了较少约束的分段动力学K. 进一步的结果表明，x和 β 值主要由 HB 间相互作用的强度 (Δυ _{i ) 决定，Δυ i}越强，x或 β 值越大。目前的工作为这种 HB 驱动的杂化体中较少约束的链段动力学提供了坚实的实验证据和新的分子水平见解，包括侧基和主链之间的平衡灵活性、阻碍协作运动的能量障碍的减少以及长链连通性的缓解。