Understanding the molecular origin of the superior toughness of polyamide-6/polyketone blends by solid-state NMR spectroscopy

作者：Zhai, Yuanming; Luo, Yong; Wang, Xiaoyan; Zhang, Chunchun; Deng, Pengchi; Chen, Hanjiao; Zhang, Rongchun^*; Bao, Ruiying; Zhou, Yicun; Yang, Mingbo; Yang, Wei^*

来源：Polymer, 2022, 259: 125324.

DOI：10.1016/j.polymer.2022.125324

• Polyamide 6
• Polyketone
• Toughness
• Solid state NMR
• Hydrogen bonds
• Interphase

Polymer blending is a typical and conventional approach for integrating the excellent physical/chemical prop-erties of individual polymer components. Specifically, the mechanical toughness and strength of polyamide-6 (PA6)/polyketone (PK) blend are substantially enhanced compared to either PA6 or PK individual component. Nevertheless, there are few atomic-level insights into such mechanical property enhancement. In this study, solid-state nuclear magnetic resonance (NMR) is utilized as a main tool to understand the molecular origin of the mechanical enhancement of PA6/PK blends. The proton relaxation times are used to evaluate the miscibility and domain sizes in PA6/PK blends, and to determine the crystallinity of each component, where both conventional DSC and WAXD experiments fail because of similar crystallization/melting behaviors of PA6 and PK components. 2D 1H-13C WISE (wideline separation) and HETCOR (heteronuclear correlation) solid-state NMR spectroscopy were performed to further reveal the nano-heterogeneous structures and hydrogen bonding interactions in PA6/ PK blend. With further combination with FTIR and SEM results, the previous characteristic morphological model for elucidating the toughening mechanism for PA6/PK blends is refuted, and it is proposed that the superior performance of PA6/PK blend is resulted from the synergistic effects of enhanced interfacial adhesion and interconnected interphase percolated in the bulk PA6/PK blends via hydrogen bonds. We envisage the detailed molecular level insights provided by solid-state NMR spectroscopy could assist in the bottom-up design of high performance polymer blend materials.

• 单位
  四川大学