二苯并冠醚和二苯氧基乙醚结构单元对可降解聚六氢三嗪热固性树脂性能的影响

Effects of Dibenzocrown Ether and Diphenoxyethylene Diether Structural Units on the Properties of Degradable Polyhexahydrotriazine Thermosetting Resins

基于同时含有柔性乙醚和刚性苯环结构的2种芳香二胺单体,4,4’-二氨基二苯并冠醚(DACr)和2,2-双(P-氨基苯氧基)乙醚(BAPE),分别与多聚甲醛经缩聚和热固化制备PHTs膜材料,通过结构表征、热性能分析、拉伸测试、接触角和耐化学试剂性能测试,以及降解性能测试等表征测试手段,探索2种结构单元对聚合物交联结构形成和性能的影响规律.研究结果表明,结构单元刚性与六氢三嗪(HT)环交联结构完善程度相关联且共同决定了PHT膜材料的性能,含柔性的非环状BAPE结构单元的PHT能形成较完整的HT交联结构,体现较高的热稳定性(5%热失重温度为296.8℃)、亲水性和相对较低的酸解程度,含较大刚性的DACr结构单元的PHT膜则具有更高的力学强度(拉伸强度53.6 MPa)、疏水性、耐有机试剂和高酸解程度,其在冰乙酸溶液中降解可获得超过83%收率的原料DACr.2种PHT材料受HT结构完善性和结构单元刚性2种结构因素共同影响,体现出相差不大的玻璃化转变温度(T_(g)分别为117.8和117.9℃).本研究工作为PHT材料结构设计及性能调控提供理论依据经验和借鉴,同时制备所得的PHT材料满足降解要求,具有潜在的应用价值.

Polyhexahydrotriazine(PHTs)films were prepared by polycondensation between the two aromatic diamine monomers and paraformaldehyde and then the thermal curing process.Those two aromatic diamine monomers were 4,4’-diaminodibenzocrown ether(DACr)and 2,2-bis(P-aminophenoxy)ether(BAPE),which contained both flexible ether and rigid benzene ring structures.Through structural characterization and a variety of performance tests,including thermal performance analysis,tensile testing,contact angle,chemical resistance performance testing,and degradation performance testing,the effect of structural units of DACr and BAPE on the crosslinking structures formation and properties of polymer were investigated.The results show that the rigidity of the structural unit was related to the completeness of the cross-linked structure of the hexahydrotriazine(HT)ring and jointly determined the performance of the PHT film material.The PHT containing the flexible acyclic BAPE structural unit tended to form perfect HT rings,and behaved the high thermal stability(5%thermogravimetric loss temperature is 296.8℃),hydrophilicity and relatively low degree of acid hydrolysis.The PHT film containing the more rigid DACr structural unit had the higher mechanical strength(tensile strength 53.6 MPa),hydrophobicity,resistance to organic reagents and the degree of acid hydrolysis,it was complete degaration in glacial acetic acid solution and recyling the raw monomer of DACr with high yield of more than 83%.Due to the influence of both the structural integrity of HT and the rigidity of the structural unit,the two PHT materials showed the similar glass transition temperatures(T_(g)s were 117.8 and 117.9℃,respectively).This study provides theoretical basis and experience for the structural design and performance regulation of PHT materials.Meantime,the obtained PHT materials meet the degradation requirements and have the potential application value.