我們利用傅式轉換紅外光譜研究乳酸與聚乳酸在二氧化鈦粉末表面上的吸附與反應。乳酸接觸到二氧化鈦表面(35 ℃)時會分解，羧酸基去質子化形成羧酸根或是羥基(O-H)斷鍵形成烷氧化合物後吸附在表面上。在無氧環境下加熱超過250 ℃，表面會有丙酸根產生並且有少量的乙酸根與氣相的二氧化碳存在。有氧環境下，反應後的產物皆為乙酸根與二氧化碳，並無丙酸根生成。乳酸在二氧化鈦上熱分解時也不會脫水生成壓克力酸根。聚乳酸的吸附方面，高分子鏈中的酯基接觸到表面會發生斷裂並且形成羧酸根的物種吸附在二氧化鈦表面上。聚乳酸熱反應的產物與乳酸相同，皆為丙酸根、乙酸根與二氧化碳。除此之外，聚乳酸/二氧化鈦在有氧下照光四小時，約有55%的聚乳酸被分解產生乙酸根與二氧化碳。本篇論文中我們也探討了乳酸與聚乳酸於二氧化鈦表面上分解可能的反應途徑。

Fourier-transform infrared spectroscopy has been employed to investigate the adsorption and reactions of lactic acid and poly(lactic acid) on powdered TiO2(35 ℃). Lactic acid can dissociate when exposed to the surface of TiO2. The carboxyl group deprotonates to form a carboxylate or the hydroxyl group breaks the O-H bond to form an alkoxy group on TiO2. As the temperature is raised higher than 250 ℃ in the absence of O2, it is found that propionate is formed, with minor acetate and gaseous CO2. In the presence of O2, acetate and CO2 are the only products detected after the lactic acid decomposition. Dehydration of lactic acid on TiO2 to form acrylate dose not occur. In the case of absorption of poly(lactic acid) on TiO2, the polyester chains are broken, forming carboxylate species, when exposed to the surface. Poly(lactic acid) has the same thermal decomposition products as those of lactic acid on TiO2. Poly(lactic acid) on TiO2 is subjected to photooxidation. Approximately 55% of poly(lactic acid) decompose to form acetate and CO2 under UV irradiation for four hours in the presence of O2. Possible decomposition mechanisms for lactic acid and poly(lactic acid) on TiO2 are proposed.

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