基于CVD液晶模板法的生物医用聚对二甲苯纳米纤维可控构筑及其降解性能研究

Poly-p-xylylene (PPX) has attracted much attention in biomedical field due to its excellent biocompatibility and functionalization. It is of great significance to prepare biodegradable PPX nanofibers with extracellular matrix structure. Aiming at the difficulty in preparation and the poor degradation of the PPX nanofibers, a novel strategy that the fabrication of PPX nanofibers in liquid crystal template via the chemical vapor deposition (CVD) and the introduction of 5,6-benzo-2-methylene-1,3-two oxygen heterocyclic heptane (BMDO) segment to the main chain of PPX is proposed in this project, to achieve the green controlled fabrication of BMDO/PPX copolymer nanofibers with both degradability and functionalization. The key influence factors and evolution rule on the microstructures of PPX nanofibers will be studied to reveal the growth mechanism of the PPX nanofibers in CVD liquid crystal system. Furthermore, the influence of BMDO on the chemical structure, aggregation structure and morphological structure of the PPX nanofibers will be investigated to clarify the regulation strategy of the copolymer nanofibers. Finally, in-depth study will be carried out to explore the influence of BMDO, fiber morphology on the degradability of the copolymer nanofibers. Structure-activity relationships of fiber structure and degradation will be established to elucidate the degradation mechanism of copolymer nanofibers. The implementation of this project will help to innovate the design and preparation of polymer nanofibers, and expand the application of PPX in the field of biomedicine.

聚对二甲苯（PPX）以其优异的生物相容性及可功能化等优点在生物医学领域备受关注，将其构建成仿细胞外基质结构的可降解纳米纤维具有重要意义。针对PPX纳米纤维难以制备及降解的问题，本项目提出采用CVD法在液晶模板内构筑PPX纳米纤维、并引入5,6-苯并-2-亚甲基-1,3-二氧杂环庚烷（BMDO）链段的新思路，旨在实现可降解功能性BMDO/PPX共聚物纳米纤维的绿色可控制备。首先探究PPX纳米纤维微观形貌的关键影响因素及其演变规律，揭示CVD液晶体系下纳米纤维的生长机制；进而明确BMDO与共聚物纳米纤维化学结构、聚集态结构和形态结构间的关系，阐明共聚物纳米纤维的调控策略；最后探明BMDO、纳米纤维形貌对共聚物纳米纤维降解性能的影响机制，建立纳米纤维结构与降解性能的构效关系，揭示共聚物纳米纤维的降解机理。本项目的实施有助于创新聚合物纳米纤维的设计、制备思路，并拓展聚对二甲苯在生物医学领域的应用。

聚对二甲苯（PPX）以其优异的生物相容性及可功能化等优点在生物医学领域备受关注，将其构建成仿细胞外基质结构的可降解纳米纤维具有重要意义。针对PPX纳米纤维难以制备及降解的问题，本项目采用CVD法在液晶模板内构筑PPX纳米纤维、并引入不饱和环状缩醛5,6-苯并-2-亚甲基-1,3-二氧杂环庚烷（BMDO）链段，成功制备了可降解功能性BMDO/PPX共聚物纳米纤维。本研究主要围绕PPX聚合物纳米纤维的构筑与性能研究开展系统研究工作，主要涉及以下三个方面：1）PPX纳米纤维的CVD液晶模板法构筑及其功能化研究，使用低浓度的单体形成气相的自由基，然后这些自由基扩散到液晶模板中，有效减小了单体所造成的液晶相变化，并能够获得具有复杂结构但能精确控制的PPX纳米纤维。2）BMDO/PPX共聚物纳米纤维的结构与形貌调控研究，将BMDO链段引入PPX分子链中并制备共聚物纳米纤维，通过单体种类、单体比、CVD沉积速率、样品台温度等对共聚物纳米纤维的化学结构、微观形貌进行调控。3）BMDO/PPX共聚物纳米纤维的构效关系研究，主要探究了BMDO/PPX-CH2OH和BMDO/PPX-alkyne两种功能化共聚物纳米纤维的降解性能、降解机理及反应活性。通过BMDO链段成功地在PPX分子链中引入酯基并赋予BMDO/PPX共聚物纳米纤维可降解性，所得共聚物纳米纤维在37°C的0.1M Na2CO3/0.1M NaHCO3的缓冲溶液体系下可有效降解。本项目的实施有助于创新聚合物纳米纤维的设计、制备思路，并拓展聚对二甲苯在生物医学领域的应用。