Electrospun nanofibers of polylactide (PLA) stereocomplex with super-hydrophobic surfaces for potential use in facial mask and biomedical applications
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Polylactide (PLA) is a biodegradable to replace the fossil-based polymers and able for use in many applications. The enantiomeric forms of PLA are poly(L-lactide) (PLLA) and poly(D lactide) (PDLA). The best stereocomplexation are made from a mixture of PLLA and PDLA in ratio 1: 1. A stereocomplex crystal form improves melting temperature and better mechanical properties. Hydrophobicity is a property that shows the wettability at surface of materials. Alkyl ketene dimers (AKD) is organic wax compound in specifically reacting between opening rings of AKD with hydroxyl groups of PLAs. In this work, process of electrospinning and film casting of PLA stereocomplex and AKD blended and coated was investigated. Additional with effect of different types and molecular weights of PLLA and PDLA (low molecular weight PLLA and hyper-branched PDLA), which studies by employing differential scanning calorimetry (DSC), fourier transform infrared (FTIR) spectroscopy, field emission scanning electron microscope (FE-SEM), polarized optical microscope (POM), universal testing machine (UTM), water contact angle (WCA) measurement, and X-Ray diffraction (XRD) machine. Stereocomplexation shows the different diameter size of fibers from different molecular weight, different crystal formation, improves mechanical and thermal properties. The surface treated-nanofibers and films show improvements in crystallinity, mechanical properties, and surface hydrophobicity. In part of stereocomplex from low molecular weight PLLA, showed the low diameter size of electrospun fibers and observed beats feature. HB-PDLA shows the increasing of stereocomplex crystallinity and good contribution of AKD blended. Casting films show the decreasing size of stereocomplex film but increasing after blended with AKD or using HB-PDLA to make a stereocomplexation. The materials have high potential for use in various applications, especially in biomedical applications as facial mask, cell scaffold, or wound dressing materials.
聚乳酸（Polylactide, PLA）是一类可替代化石基聚合物的可生物降解材料，适用于众多应用场景。PLA的对映异构形式包括聚L-乳酸（poly(L-lactide), PLLA）与聚D-乳酸（poly(D-lactide), PDLA）。当PLLA与PDLA以1:1的比例混合时，可形成性能最优的立体复合物。立体复合晶体结构可提升材料的熔融温度与力学性能。疏水性是表征材料表面润湿性的重要属性。烷基烯酮二聚体（alkyl ketene dimers, AKD）是一类有机蜡类化合物，可通过AKD的开环反应与PLA的羟基基团发生特异性结合。 本研究针对PLA立体复合物与AKD共混、涂层体系的静电纺丝及流延成膜工艺展开了探究，同时考察了不同类型及分子量的PLLA与PDLA（低分子量PLLA及超支化PDLA）对体系的影响，研究过程中采用了差示扫描量热法（differential scanning calorimetry, DSC）、傅里叶变换红外（fourier transform infrared, FTIR）光谱、场发射扫描电子显微镜（field emission scanning electron microscope, FE-SEM）、偏光显微镜（polarized optical microscope, POM）、万能试验机（universal testing machine, UTM）、水接触角（water contact angle, WCA）测试以及X射线衍射（X-Ray diffraction, XRD）仪等表征手段。 研究结果表明，立体复合结构可改变不同分子量样品所得纤维的直径尺寸与晶体形成过程，同时提升材料的力学与热学性能。经表面改性的纳米纤维与薄膜的结晶度、力学性能及表面疏水性均得到改善。针对低分子量PLLA制备的立体复合物，其静电纺丝纤维直径更小，且观察到了珠状形貌特征。超支化PDLA可提升立体复合物的结晶度，同时对AKD共混体系具有良好的协同作用。流延薄膜的立体复合物晶粒尺寸会出现下降，但在与AKD共混或采用超支化PDLA制备立体复合物后，晶粒尺寸会有所提升。该材料在众多应用场景中具有较高的应用潜力，尤其可应用于生物医学领域，例如用作面膜、细胞支架或伤口敷料材料。
