The structure and properties of OMt prepared by a synergistic modification strategy using the emulsifier OP-10 and hexadecyltrimethylammonium chloride as comodifiers

Abstract

Abstract To improve the application performance of organic montmorillonite (OMt) and meet the OMt performance requirements of different fields, herein, we developed a synergistic modification method to prepare cationic–nonionic OMt (CN-Mt) using the emulsifier OP-10 and hexadecyltrimethylammonium chloride (CTAC) as comodifiers. The structure, morphology and properties of CN-Mt, cationic-OMt (C-Mt) and nonionic OMt (N-Mt) were studied by XRD, SEM, DSC, and contact angle and swell index measurements. CN-Mt has a larger layer spacing and thinner lamellae, which are obviously different from those of C-Mt and N-Mt. Moreover, CN-Mt was hydrophobic due to its denser organic surface molecules. The interlayer spacing of CN-Mt is positively related to the amount of modifier, and the amount of OP-10 contributes more to the interlayer spacing than CTAC. When the amounts of OP-10 and CTAC are 1.3 and 0.8 times the Mt cation exchange capacity (CEC), the interlayer spacing of the optimal CN-Mt is 4.49 nm, which is significantly higher than that of C-Mt (4.11 nm) at a 2.9 CEC, N-Mt (4.26 nm) at a 1.7 CEC and CN-Mt (4.20 nm) at a 0.9OP-10 + 1.5CTAC CEC. Benefitting from its structural merits, CN-Mt shows a higher degree of lamella separation, peeling and dispersion than C-Mt and N-Mt, as well as good thermal stability. Moreover, the lipophilicity and expansion of CN-Mt in medium- and low-polarity media are better than those of single-component OMt. Therefore, the structure and properties of CN-Mt can be controlled by adjusting the types and amount of modifier, further meeting the performance requirements of various application fields.