表面构建聚多巴胺制备抗紫外线PBO纤维

Preparation of UV-resistant PBO fibers by surface-building polydopamine

基于聚对苯撑苯并双噁唑(PBO)纤维分子链中噁唑五元环不稳定,紫外光辐射下噁唑环发生开环,大分子发生断裂,导致力学性能急剧下降的问题,通过PBO纤维表面涂覆聚多巴胺(PDA)分子链的方法,合成了耐紫外PBOPDA改性纤维。采用扫描电子显微镜、傅里叶变换红外光谱、广角X射线散射等分析手段研究了表面涂覆对PBO纤维表观形貌、超分子结构、微纳结构及抗紫外老化性能影响。结果表明:经过288 h紫外光辐射,PBO纤维分子链中产生酰胺基团,结晶峰的位置较老化前相对向右移动,结晶区的微小晶体发生相对滑移,结晶度、晶面取向度降低,结晶区出现解取向,原纤间微孔的直径、长度增大,纤维表面出现多条平行排列细长条纹,纤维力学强度急剧下降;而改性PBO-PDA纤维氮气氛围下热分解温度为693.6℃,仍具有良好的热分解稳定性,经紫外老化288 h后的PBO-PDA纤维具有较好抗紫外线能力,表层PDA分子链可有效阻隔紫外光对内部PBO纤维的破坏,纤维结晶度改变较小,纤维内部微孔直径长度增大幅度较小,分子结构没有额外基团产生,拉伸强度仍为1.55 GPa,拉伸强度保留率为37.26%。

Based on the unstable five-membered ring of oxazole in the molecular chain of poly(p-phenylene benzobisoxazole)(PBO) fibers,the oxazole ring opens and the macromolecule breaks under UV radiation,which leads to a drastic decrease in the mechanical properties,UV-resistant PBO-PDA-modified fibers were synthesized by the method of polydopamine(PDA) molecular chain coating on the surface of PBO fibers.The influence of surface coating on the apparent morphology,supramolecular structure,micro-nanostructure,and UV aging resistance of PBO fibers was investigated using scanning electron microscopy,Fourier transform infrared spectroscopy,wide-angle X-ray scattering,and other analytical methods.The results show that after 288 h of UV radiation,amide groups are generated in the molecular chain of PBO fiber,the position of the crystallization peak move relatively to the right compared with that before aging,the tiny crystals in the crystalline region slip relatively,the degree of crystallinity,the degree of crystal face orientation decrease,the crystalline region appear to be de-orientation,the original inter-fiber pore diameter and length increase,the surface of the fiber appear to have many parallel aligned elongated stripes,and the mechanical strength of the fiber decrease dramatically.Modified PBO-PDA fiber,nitrogen atmosphere thermal decomposition temperature of 693.6 ℃,still has a good thermal decomposition stability,the UV aging of 288 h after the PBO-PDA fiber has a better UV resistance,the surface layer of the PDA molecular chain can effectively block the destruction of UV light on the internal PBO fibers,the fiber crystallinity change is small,the diameter and length of the microporous fibers within the increase in size of a small amount,the molecular structure has no additional groups generated,the tensile strength remains 1.55 GPa,and the tensile strength retention rate is 37.26%.