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指導教授：王振乾 學 生：蕭詠方 Outline Abstract Introduction Experimental Results and discussion Conclusion Abstract 利用溶膠-凝膠法製備具可塑性的聚乳酸(PLA)-二氧 化矽(silica)奈米複合材料. IR XRD TGA Tensile testing SEM 使用矽烷化合物, 在酸或鹼的催 化下, 連續進行水解及縮合反應. 結果顯示 聚乳酸(PLA)的C-O-C基團震動峰受二氧化矽(silica)網狀結構限制而減 弱. 聚乳酸(PLA)的結晶度受二氧化矽(silica)網狀結構限制而下降. 存在少量的二氧化矽(silica)可提升材料的拉伸強度. 添加二氧化矽(silica)可改善材料的熱穩定性. Introduction PLA具生物可分解性、生物相容性等優點, 且具良好的加工性. 但其為硬質易脆材料、耐撓曲性差, 在應用上受到限制. 添加生物可分解的可塑劑, 如聚乙二醇(PEG), 可增進PLA的韌 性或撓曲性, 幫助延伸、耐衝擊. 近年來, 製備PLA奈米複合材料以添加蒙脫土、雲母等較為常見, 研究顯示, 以PLA/PEG為基材, 添加有機改質蒙脫土可改善材料 的性質. 此研究目的主要以PLA/PEG為基材, 利用溶膠-凝膠法製備具可 塑性的PLA-silica奈米複合材料. 探討奈米複合材料的合成過程、 結構、熱與機械性質. Experimental Materials Poly(L-lactic acid) (PLA) (Mn=70,000) Poly(ethylene glycol)400 (PEG, Mw=400) Tetraethyloxysilane (TEOS) Glycidoxypropyltrimethoxysilane (GPTMS) Hydrochloric acid (HCl) tetrahydrofuran (THF) Experimental Preparation of PLA/PEG/silica nanocomposites 1. HCL/TEOS/GPTMS 2. 3. 於THF中加熱攪 拌至完全溶解 PLA and PEG 400 was melt blending at 8:2 添加不同比例的矽烷化合 物(0%. 3%. 5%.8%12%) EtOH Deionized water HCl PLA/PEG400 solution 完全混合 homogeneous solution THF 室溫 Homogeneous solution 2hr TEOS、GPTMS發 生水解且透明具黏 性的溶膠形成 4. Covered with perforated polyethylene film 溶膠 靜置4天 5. 凝膠 以聚乙烯為載體 的凝膠材料形成. vacuum dried remove the residue water and THF. 60℃, 24hr PLA/PEG/0%silica 模壓成型 6. Sample PLA/PEG/3%silica thickness of about 0.5mm PLA/PEG/5%silica PLA/PEG/8%silica 150℃,15MPa PLA/PEG/12%silica GPTMS TEOS Silica network IR Results and discussion Silica 插入高分子基材, Si-O-Si特 性吸收峰約在1086 cm−1, 因與 C-O-C peak重疊, 故未觀察到. C-O-C peaks 隨著Silica含量增加而 減弱. 1086cm 1 Silica 網狀結構會限制C-O-C基團 的振動. Si-OH C–O–C vibration of PLA and PEG 交聯密度過高, 不會完全生成二氧 化矽結構, 而會殘存少許矽醇, 觀 察到Si-OH peak 在961 cm−1左右, 且隨silica含量增加而變強. 1086cm 1 證實, silica與高分子基材反應成功. XRD Results and discussion α structure 10^3 helices chain β structure All systems exhibit the diffraction peaks with the same position located at 2θ=16.7, 19.0, and 22.3, which can be ascribed to the crystal structure of PLA. PLA/PEG polymer matrix doesn't exhibit any crystalline phase of PEG because of the low molecular weight of PEG 400. 結晶尺寸 PLA的結晶位置沒有改變. 添加silica不會使PLA結晶分裂或 改變結晶結構. 結晶peak隨silica含量增加而減 小. 堅固的silica網狀結構, 限制PLA的 結晶鏈運動. Tensile testing Results and discussion 3% tensile strength increases with silica content and reaches the maximum at 3 wt.% silica loading, then decreases when the silica loading further increases. It is evident that the presence of even a small amount of inorganic component largely improves the mechanical properties of the composites. SEM Results and discussion 3% with silica PLA/PEG blend is relatively smooth. PLA/PEG blend 12% with silica with 3 wt.% silica content is rough with 12% with silica silica particle dispersion on the surface. Most silica nanoparticles assume spherical shape with a particle size of 20– 30 nm. with 12 wt.% silica loading, the SiO2 nanoparticles tend to agglomerate. The agglomeration of silica particles acts as stress concentrators when the samples are subjected to stress, which results in the deterioration of mechanical properties. TGA Results and discussion 熱裂解溫度隨silica含量增加 而增加. silica 熱穩定性極佳, 添加 silica後,高分子與silica 網狀結 構會形成互穿式的結構,因此 複合材料的整體熱穩定性提 升. Thermal stability of samples is improved with silica loading Conclusion Plasticized poly(L-lactide)-silica nanocomposite materialshave been successfully fabricated by sol–gel method. IR and XRD measurements show that both the vibration of C– O–C group and the crystallization of PLA are confined by silica network. The presence of even a small amount of silica greatly improved the tensile strength of the samples. The thermal stability of samples is improved with silica loading.