基于生物基PEF聚酯的高韧性高阻隔性多嵌段共聚物

Poly(ethylene furandicarboxylate) (PEF) is an important biobased polyester with excellent mechanical strength and gas barrier properties, and therefore is a promising material for high gas barrier package materials and engineering plastics. However, PEF is very brittle and its gas barrier and mechanical properties decrease when toughened by random copolymerization. To address these problems and to aim at high performance PEF materials, in this project, multi-block copolymers composed of PEF hard segment and high barrier soft segment are designed and synthesized to simultaneously realize high toughness and high gas barrier. Incorporating soft segments which is micro-phase separated from PEF hard segment results in effective toughening; Incorporating soft segments which is highly gas-tight simultaneously realize toughening and barrier promotion; Incorporating PEF nanocomposite hard segment and/or crystallization promotion of PEF segment by unique DEGF unit depression and distinctive self-nucleation further improve the gas barrier and enhancing the mechanical properties. The researches focus on the following fundamental scientific and key technical problems, including: (1) Methods and technologies of synthesis, crystallization promotion and nanocomposite of PEF and its multi-block copolymers; (2) The influencing rules of soft segment structure/content, micro-phase separation, hard segment crystallization and nanocomposite structure on the gas barrier and mechanical properties. The implement of this project will realize innovations in biobased PEF materials and preparation technologies. It will help us to obtain new PEF-based materials with high strength, toughness and gas barrier properties and corresponding preparation technologies, and to elucidate the involved structure-property relationships. The research results will provide technical support for the industrialization and applications of PEF materials.

聚(呋喃二甲酸乙二醇酯) (PEF)具有优异的力学强度和气体阻隔性，是重要的生物基聚酯，在高阻隔包装材料、工程塑料领域应用前景广阔，但其结晶性差、性脆且增韧易导致力学性能和阻隔性下降。本项目针对这些问题，以PEF的高性能化为目标，设计合成由PEF硬段和高阻隔软段组成的高韧性高阻隔多嵌段共聚物；通过微相分离结构的设计，实现高效增韧；通过高阻隔软段的引入，同时实现增韧和增阻；通过PEF硬段的纳米复合和独特的自成核结晶促进，进一步提高阻隔性和力学性能。重点研究PEF及其多嵌段共聚物的合成、结晶性调控和纳米复合技术及软段结构、硬段结晶性和纳米复合结构对阻隔和力学性能的影响规律等关键科学、技术问题，解决高韧性高阻隔PEF多嵌段共聚物的制备技术问题，阐明其结构与性能之间的关系。本项目的实施，将实现生物基PEF材料和制备技术的创新，获得高性能PEF新材料及其制备技术，为PEF的工业化和应用打下基础。

聚(2,5-呋喃二甲酸乙二醇酯) (简称PEF)是重要的生物基聚酯，具有比聚对苯二甲酸乙二醇酯(PET)更高的玻璃化温度、拉伸强度与模量及气体阻隔性，在高阻隔包装材料(如高阻隔膜和瓶)领域具有广阔的应用前景。但PEF属于典型的脆性材料，断裂伸长率(2-5%)和冲击强度(2-3 kJ/m2)均很低，且结晶性差，不利于应用。为获得具有实用价值的PEF材料，本项目开展了PEF的增韧和结晶促进的研究。设计合成了两种以PEF硬段的多嵌段共聚物，实现了从脆性塑料到韧性塑料的转变，甚至还可得到弹性体材料，大幅改善了PEF的延展性（断裂伸长率高达250%），较好地改善了冲击韧性（提高100%），并保持高的强度和气体阻隔性，其中PEF-PHC15可保持5倍于PET的CO2阻隔性；设计和合成多种PEF无规共聚酯，显著改善了PEF的延展性，同时更好地保持拉伸强度和模量（几乎不变）和气体阻隔性(仅下降11-14%)；通过原位缩聚法制备了PEF-MMT纳米复合材料，大幅改善PEF结晶性、刚性和强度；通过溶解-沉淀处理明显改善PEF结晶性，获得了晶型的PEF，将其用作PEF的自成核剂，有效促进了PEF的结晶。通过以上研究，很好地弥补了PEF在延展性、冲击韧性和结晶性方面的性能短板，同时较好地保持了PEF在强度、模量和阻隔性方面的性能优势，为PEF进一步的开发和应用打下了基础。