Pickering emulsification of pyrrolidone-based block copolymer aggregates: Effects of copolymer composition and oil

• Published in: Colloids and surfaces. A, Physicochemical and engineering aspects Physicochemical and engineering aspects, 2024-12, Vol.702, p.135123, Article 135123
• Main Authors: Li, Chunhui, Cheng, Shuozhen, Dong, Jinfeng, Li, Xuefeng
• Format: Article
• Language: English
• Subjects: Block copolymers; Micelles; Multiple emulsions; Pickering emulsions; Self-assembly; Vesicles
• ISSN: 0927-7757
• DOI: 10.1016/j.colsurfa.2024.135123

A series of block copolymers poly (N-2-(methacryloyloxy) ethyl pyrrolidone)-b-poly (benzylmethacrylate) (PNMP39-b-PBzMAn) were developed. These amphiphilic copolymers formed diversified aggregates in water, depending on the degree of polymerization n of the PBzMA segment. There presented the n-induced morphological transition from spherical micelles to vesicles via wormlike micelles. Moreover, PNMP39-b-PBzMAn aggregates were excellent dual function emulsifiers, showing similarity with both particles and surfactants simultaneously. The emulsification of PNMP39-b-PBzMAn aggregates was affected significantly by the degree of polymerization n of the PBzMA segment and oil. However, the effect of oil was more remarkable in comparison with that of n, in which the compatibility between oil and the hydrophobic PBzMA segment was critical. In general, O/W and W/O emulsions were formed for oils with poor and good compatibility to the PBzMA segment such as nonpolar alkanes and toluene, respectively. In these cases, PNMP39-b-PBzMAn aggregates were remained in water in the alkane/water systems, whereas they were transferred into the toluene phase according to the similarity-intermiscibility principle. For isopropyl myristate, a polar oil with the intermediate compatibility to the PBzMA segment, PNMP39-b-PBzMAn in water were transferred into the oil phase partially. Accordingly, emulsifiers in water and oil benefit the formation of O/W and W/O emulsions, respectively, as observed in the alkane/water and toluene/water systems. As a result, O/W and W/O emulsions were generated by PNMP39-b-PBzMAn with relatively small and large n, respectively. For PNMP39-b-PBzMAn with the intermediate n, W/O/W multiple emulsions were formed attributing to the synergistic emulsification of PNMP39-b-PBzMAn in water and oil. [Display omitted]