Abstract: Electrostatic spinning technology is an efficient method for the preparation of nanofiber materials. The fiber materials produced by this method have high porosity and specific surface area, and their fiber structure can mimic the extracellular matrix, making them an ideal material for promoting repair and regeneration of damaged parts in tissue engineering. PLCL is a synthetic polymer material with high biosafety and degradability, and is widely used in tissue engineering and drug delivery. However, the poor hydrophilicity and poor biocompatibility of PLCL electrospun fiber materials limit their applications. The hydrophilicity of composite or pure PLCL fiber materials is often improved by mixing them with hydrophilic natural or synthetic polymer materials or post-treating PLCL microfiber nonwoven materials, etc. However, the composite fiber material made by the former method is unstable in structure and prone to phase separation, and some of the natural polymer materials have large brittleness and poor flexibility, resulting in poor mechanical properties of the composite material. By contrast, the composite fiber material made by the latter method is unstable in effect, and is prone being hydrophobic from being hydrophilic after a period of use.
By changing the ratios of hexafluoroisopropanol (HFIP) and trifluoroacetic acid (TFA) in the electrostatic spinning solution, the wettability of poly(propylene lactone-caprolactone) (PLCL) microfibrous nonwoven materials was changed in a one-step method without adding any hydrophilic components or finishing. PLCL was dissolved in a solvent mixture of HFIP and TFA and then electrostatically spun, and it was found that the average fiber diameter decreased from 1.036 μm to 0.611 μm with the increase of TFA content from 0 to 100%, and the contact angle decreased from 121° in the droplet method to 46° in the bubble method. The infrared spectra, thermogravimetric curves, X-ray diffraction curves, and nuclear magnetic hydrogen spectra of the materials were further tested to investigate the mechanism of the phenomenon. The experimental results showed that the addition of TFA shortened the chain segment of PLCL macromolecule and reduced the number of hydrophobic ester groups, which led to the decrease of fiber diameter and the increase of hydrophilicity of the material. Nevertheless, the addition of TFA did not change the thermal stability of the material as a whole, and did not produce new chemical structures, and the hydrolysis occurred firstly in the amorphous region of the PCL molecule. It is proved that hydrophilic PLCL microfiber nonwoven materials can be prepared simply and efficiently by changing the solvent ratio.
PLCL microfiber nonwoven materials can be applied to tissue engineering dressings, inoculating epidermal cells or fibroblasts based on the polymer scaffold material can be used to repair patients' wound to increase the degree of active growth factor secretion. Since hydrophilic materials are easier for cell adhesion and biocompatible, improving the wettability of PLCL microfiber nonwoven materials is one of the keys to expanding their applications.

Key words: PLCL, electrostatic spinning, hydrophilic, trifluoroacetic acid, hydrolyze

摘要： 为探究三氟乙酸（TFA）对聚丙交酯-己内酯（PLCL）润湿性能的影响，通过调节静电纺丝溶液中六氟异丙醇（HFIP）和TFA的配比，在不添加任何亲水成分和后整理剂的情况下，通过一步法实现PLCL超细纤维非织造材料的润湿性调控。将PLCL溶于HFIP和TFA的混合溶剂后进行静电纺丝，随着TFA体积分数从0增加到100%，PLCL大分子链段逐渐变短、纺丝液黏度降低，纤维平均直径从1.036 μm降低到0.611 μm，接触角从121°（液滴法）降低到46°（气泡法）。通过EDS、红外、热重、XRD及核磁氢谱测试研究机理，结果表明：TFA的加入并没有使PLCL分子产生新的化学结构，但会使PLCL中的PLA链段和PCL链段发生水解，导致PLCL大分子链段中疏水性酯基数目减少，PLCL亲水性增加。该研究结果可为简单高效制备出亲水PLCL超细纤维非织造材料提供借鉴。

关键词: 聚丙交酯-己内酯（PLCL）, 静电纺丝, 亲水性, 三氟乙酸, 水解