无溶剂法制备丙烯海松酸蔗糖酯及其在空气-水界面吸附行为研究

Preparation of Acrylic Pimaric-sucrose Ester by Solvent-free Process and Its Adsorption Properties at Air-water Interface

在无溶剂条件下,以丙烯海松酸和蔗糖为原料,在高温熔融状态下通过酯化反应制备了丙烯海松酸蔗糖酯,运用红外光谱、核磁共振和凝胶渗透色谱对其结构进行了表征,并测试了其临界胶束浓度(CMC),利用再定向理论分析了丙烯海松酸蔗糖酯表面活性剂在空气-水界面的形态转变和吸附量等吸附行为。研究结果表明:成功合成了丙烯海松酸蔗糖酯,其CMC值为2.2 g/L。丙烯海松酸蔗糖酯在空气-水界面的吸附状态分为状态1和状态2,随着表面压的增加,溶剂摩尔分数逐渐降低,2种状态丙烯海松酸蔗糖酯分子在空气-水界面上的摩尔分数之和逐渐增加。计算了吸附在界面上的状态1和状态2丙烯海松酸蔗糖酯的吸附量,随着表面压增大,状态1吸附量先增大后减小,状态2吸附量占主导且持续增多,吸附量最高可达1.9 mmol/m2。丙烯海松酸蔗糖酯的吸附和胶束化摩尔自由能(ΔG)分别为-20.67和-15.16 kJ/mol,表明丙烯海松酸蔗糖酯优先吸附在界面上,达到饱和后就形成胶束。

Acrylic pimaric-sucrose ester was synthesized from acrylamicarboxylic acid and sucrose by esterification at high temperature under solvent-free conditions,which structure was characterized by IR,NMR and gel permeation chromatography and critical micelle concentration(CMC)was measured.The reorientation theory was used to analyze the adsorption behaviors of acrylic pimaric-sucrose ester surfactant at the air-water interface,including morphological change and adsorption capacity.The results showed that the acrylic pimaric-sucrose ester was successfully synthesized by the method,and the CMC value the synthesized ester was 2.2 g/L.With the increase of surfactant concentration,the solvent molar fraction at the air-water interface decreased,while the molar fraction of acrylic pimaric-sucrose ester increased.The adsorption of acrylic pimaric-sucrose ester at the air-water interface was divided into state 1 and state 2,and the adsorption capacity on the interface was calculated respectively,which was up to 1.9 mmol/m2 in state 2.As the surface pressure increased,the number of molecules in state 1 increased first and then decreased,while the number of molecules in state 2 dominated and continued to increase.The molar free energies(ΔG)of adsorption and micelles of acrylic pimaric-sucrose ester were-20.67 kJ/mol and-15.16 kJ/mol,respectively,indicating that acrylic pimaric-sucrose ester was preferentially adsorbed on the interface and formed micelles after reaching saturation.