Dynamic Polyamide Networks via Amide–Imide Exchange,Macromolecules

当前位置： X-MOL 学术 › Macromolecules › 论文详情

Our official English website, www.x-mol.net, welcomes your feedback! (Note: you will need to create a separate account there.)

Dynamic Polyamide Networks via Amide–Imide Exchange
Macromolecules ( IF 5.1 ) Pub Date : 2021-10-13 , DOI: 10.1021/acs.macromol.1c01389
Yinjun Chen ₁ , Huiyi Zhang ₁ , Soumabrata Majumdar ₁ , Rolf A T M van Benthem _{2,

3} , Johan P A Heuts ₁ , Rint P Sijbesma ₁

Affiliation

The diamide–imide equilibrium was successfully exploited for the synthesis of dynamic covalent polymer networks in which a dissociative bond exchange mechanism leads to high processibility at temperatures above ≈110 °C. Dynamic covalent networks bridge the gap between thermosets and thermoplastic polymers. At the operating temperature, when the network is fixed, dynamic covalent networks are elastic solids, while at high temperatures, chemical exchange reactions turn the network into a processible viscoelastic material. Upon heating a dissociative network, the viscosity may also decrease due to a shift of the chemical equilibrium; in such materials, the balance between processibility and excessive flow is important. In this study, a network is prepared that upon heating to above ≈110 °C dissociates to a significant extent due to a shift in the amide–imide equilibrium of a bisimide, pyromellitic diimide, in combination with poly(tetrahydrofuran) diamines. At room temperature, the resulting materials are elastic rubbers with a tensile modulus of 2–10 MPa, and they become predominantly viscous above a temperature of approximately 110 °C, which is dependent on the stoichiometry of the components. The diamide–imide equilibrium was studied in model reactions with NMR, and variable temperature infrared (IR) spectroscopy was used to investigate the temperature dependence of the equilibrium in the network. The temperature-dependent mechanical properties of the networks were found to be fully reversible, and the material could be reprocessed several times without loss of properties such as modulus or strain at break. The high processibility of these networks at elevated temperatures creates opportunities in additive manufacturing applications such as selective laser sintering.

中文翻译：

通过酰胺-酰亚胺交换形成动态聚酰胺网络

二酰胺-酰亚胺平衡已成功用于动态共价聚合物网络的合成，其中解离键交换机制导致在约110°C以上的温度下具有高可加工性。动态共价网络弥合了热固性材料和热塑性聚合物之间的差距。在工作温度下，当网络固定时，动态共价网络是弹性固体，而在高温下，化学交换反应将网络变成可加工的粘弹性材料。加热解离网络时，由于化学平衡的移动，粘度也可能降低；在此类材料中，可加工性和过度流动之间的平衡很重要。在这项研究中，制备了一个网络，当加热到约 110 °C 以上时，由于双酰亚胺、均苯四甲酸二酰亚胺与聚四氢呋喃二胺的酰胺-酰亚胺平衡发生变化，该网络会在很大程度上解离。在室温下，所得材料是拉伸模量为 2-10 MPa 的弹性橡胶，在大约 110 °C 的温度以上，它们主要变得粘稠，这取决于组分的化学计量。在模型反应中用 NMR 研究了二酰胺-酰亚胺平衡，并使用变温红外 (IR) 光谱研究了网络中平衡的温度依赖性。研究发现，网络的与温度相关的机械性能是完全可逆的，并且该材料可以多次再加工，而不会损失模量或断裂应变等性能。这些网络在高温下的高加工性为增材制造应用（例如选择性激光烧结）创造了机会。

更新日期：2021-10-26

点击分享查看原文

点击收藏

公开下载

阅读更多本刊新发论文本刊介绍/投稿指南