不同烷基链长度脂肪酸钾凝胶的微晶结构及热稳定性  

Crystalline Structure and Thermal Stability of Fatty Acid Potassium Gels with Different Alkyl Chain Lengths

作　　者：巩涛 王小永[1] GONG Tao;WANG Xiaoyong(School of Chemistry and Molecular Engineering,East China University of Science and Technology,Shanghai 200237,China)

机构地区：[1]华东理工大学化学与分子工程学院,上海200237

出　　处：《华东理工大学学报（自然科学版）》2023年第4期508-514,共7页Journal of East China University of Science and Technology

基　　金：国家自然科学基金(21573071,22273022)。

摘　　要：研究了月桂酸钾(LK)和棕榈酸钾(PK)凝胶的微晶结构、流变性质及热稳定性。在室温和偏光显微镜下,质量分数为30%的LK凝胶呈现条带状微晶交叉堆积状态,而质量分数为30%的PK凝胶呈现线状微晶纤维束状态。X射线衍射结果表明,不同质量分数的LK保持水合层状微晶结构,增大PK质量分数会使其从水合层状微晶结构转变为无水层状微晶结构。当温度升高时,LK转变为六角相液晶和球形胶束结构,PK转变为层状液晶结构。PK凝胶的储能模量和损耗模量均是LK凝胶对应值的10倍以上,且在20~60℃未出现突降,说明由长烷基链脂肪酸钾形成的PK凝胶具有更强的微晶网络结构和更高的热稳定性。Fatty acid potassium is an important surfactant for daily chemical products and cosmetics industries with high foaming,soft texture and other advantages.In recent years,as a"green"soft matter,the fatty acid potassium gel has been applied in drug carriers,nanomaterials and phase change materials.However,many important aspects such as the crystalline structure,formation mechanism and thermal stability of fatty acid potassium gel remain unclear.This paper investigated the crystalline structure,rheological property and thermal stability of potassium laurate(LK)and potassium palmitate(PK)gels.At room temperature,polarized optical micrographs revealed strip-like crystals with cross stacking in 30%LK gel and linear crystalline fiber bundles in 30%PK gel.LK and PK gel formed at 30%LK concentration and 6%PK concentration,respectively.This was mainly ascribed to the stronger hydrophobic effect of the longer alkyl chain of PK than that of LK.X-ray diffraction showed that LK molecules of different concentrations retained the hydrated lamellar crystallites,while PK hydrated lamellar crystallites changed into anhydrous lamellar crystals with increasing PK concentration.Upon heating,LK hydrated lamellar crystallites transformed into hexagonal liquid crystallites and spherical micelles,and PK anhydrous lamellar crystallites changed into lamellar liquid crystallites.PK gel had basically stable storage and loss modulus at 20—60℃,which were 10 times higher than those of LK gel.These results indicated that PK gel formed by long alkyl chain fatty acid potassium had stronger crystalline network structure and higher thermal stability than those of LK gel.

关 键 词：脂肪酸钾 层状微晶 液晶 储能模量 热稳定性 

分 类 号：O647.2[理学—物理化学]