聚对二甲苯纳米纤维阵列的CVD液晶模板法制备及降解性能

Fabrication of Poly(p-xylene)Nanofiber Arrays by CVD Liquid Crystal Template Method and Their Degradability

聚对二甲苯(PPX)具有优异的生物相容性和化学稳定性,将其构建成仿细胞外基质结构的可降解纳米纤维在生物工程领域具有重要意义.本文采用化学气相沉积(CVD)法,以向列型热致液晶E7为模板,以4-羟甲基-对二甲苯二聚体(PCP-CH_(2)OH)为聚-(4-羟甲基-对二甲苯)(PPX-CH_(2)OH)的前驱体,通过在其分子链上引入5,6-苯并-2-亚甲基-1,3-二氧杂环庚烷(BMDO)链段制备BMDO/PPX-CH_(2OH共聚物纳米纤维阵列,探讨了共聚物纳米纤维阵列形貌的影响因素,分析得到了制备共聚物纳米纤维阵列的最佳反应条件,并研究了BMDO/PPX-CH_(2)OH共聚物纳米纤维阵列的生物降解性能.研究表明,在液晶模板作用下,通过CVD法成功地使PCP-CH_(2)OH与BMDO共聚,并得到了BMDO/PPX-CH_(2)OH共聚物纳米纤维阵列;其形貌主要受样品台的温度和沉积速率的影响,而单体质量比影响较小;经优化后CVD最佳条件为:样品台温度-10℃,沉积速率约为0.01 nm/s,单体质量比为10∶1;共聚物在37℃的0.1 mol/L Na_(2)CO_(3)/0.1 mol/L Na HCO_(3)的缓冲溶液体系下可有效降解,当降解时间超过23 d后,纳米纤维阵列中的酯基可完全分解;当降解时间超过30 d时,纳米纤维阵列基本降解完全,总体呈碎片状.

Benefiting from the superior biocompatibility and chemical stability of poly(p-xylylene)(PPX),it is of great significance to construct biodegradable PPX nanofiber arrays mimicking extracellular matrix structure in the bioengineering field.To tackle the problems of fabrication and degradation for PPX nanofiber,BMDO/PPX-CH2OH copolymer nanofiber arrays were prepared via chemical vapor deposition(CVD)using liquid crystal as template,4-hydroxymethyl-p-xylene(PCP-CH_(2)OH)as precursor of poly(4-hydroxymethyl-p-xylene)(PPX-CH2OH)and 5,6-benzo-2-methylene-1,3-dioxyheterocyclic heptane(BMDO)was introduced to copolymerize with PCP-CH_(2)OH to endow the molecular chains with degradable property.The results indicated that PCP-CH2OH was successfully copolymerized with BMDO via CVD approach,and the copolymer nanofiber arrays were obtained.The morphology of the copolymer nanofiber arrays was related to the sample holder temperature and deposition rate,while the mass ratios of BMDO to PCP-CH2OH showed no obvious effect.The optimized CVD process is that the sample holder temperature is about-10℃,the deposition rate is about 0.01 nm/s,and the mass ratio of BMDO to PCP-CH2OH is 10∶1.The as-prepared copolymer nanofiber arrays could be degraded effectively in the carbonate buffer solution(0.1 mol/L Na_(2)CO_(3)+0.1 mol/L NaHCO3)at 37℃.The ester group in the nanofiber arrays could be decomposed completely after 23 d,and the nanofiber arrays became tiny fragments after 30 d,indicating that the nanofiber arrays were basically completely degraded.