間苯二酚／甲醛製備水凝膠及氣凝膠之性質

Properties of Hydrogels and Aerogels Prepared from Resorcinol/Formaldehyde

本研究利用間苯二酚（Resorcinol；R）、甲醛（Formaldehyde；F）及水（Water；W）混合物製作RF水凝膠（Hydrogels），並將水凝膠利用冷凍乾燥脫水製作RF氣凝膠（Aerogels）。探討 F/R及W/R莫耳比對所RF水凝膠及氣凝膠性質之影響。由試驗結果得知，在密閉環境中，間苯二酚與甲醛可於大量水存在之系統中進行聚縮合反應形成水凝膠。隨W/R莫耳比提高，凝膠化所需時間延長，水凝膠之壓縮強度則降低。提高F/R莫耳比可縮短凝膠化時間，但對水凝膠之機械性質影響不明顯。氣凝膠之FTIR分析結果顯示，F/R莫耳比較高者，其間苯二酚之苯環結構之取代度較大。 DSC分析顯示，氣凝膠在熱掃描過程出現分子鏈熱活動之吸熱峰。隨F/R莫耳比提高，氣凝膠再吸水之能力降低，丙酮溶出之重量損失則增加。TGA熱分析顯示，隨W/R及F/R莫耳比提高，氣凝膠之熱抵抗性降低。 In this study, RF hydrogels were prepared by mixtures of resorcinol (R), formaldehyde (F), and water (W). The RF aerogels were made from RF hydrogels by dehydrating with freeze drying. The effect of the molar ratio of F/R and W/R on the properties of RF hydrogels and aerogels were investigated. The results showed that the polycondensation reaction between resorcinol and formaldehyde could be carried out in the system with a large amount of water to form hydrogels at a sealed environment. Increasing the malar ratio of W/R, the time needed for gelation prolonged and the compression strength of hydrogel decreased. However, increasing the malar ratio of F/R, the gel time could be shortened but which had no obvious influence on the mechanical properties of hydrogels. FTIR analysis results of aerogel showed that the higher the F/R molar ratio, the higher substituted degree of aromatic ring of resorcinol did. DSC analysis showed an endothermic peak due to the thermal activity of molecular chain during the heat scanning. Increasing the malar ratio of F/R, the water re-absorption capability of aerogels decreased, the weight loss after acetone dissolving increased. TGA results showed that the heat resistance of aerogel decreased with the molar ratio of W/R and F/R increasing.