Molecular origin of pyrrolidone-based dynamic imine covalent copolymers on self-assembly and emulsification

In this work, block copolymers poly(N-(2-methacryloylxyethyl) ethyl pyrrolidone)- block -poly(4-(formaldehyde) phenyl methacrylate) (PNMP 72 - b -PBFMA m ) were synthesized as aldehyde precursors D m . Based on the mixtures of aldehyde precursors D m and different amino precursors A including alkylamine (HC n A , n represents the carbon number), 1, ω-alkyl diamine (HC n DA) and perfluoroalkylamine (FC n A) at the constant -NH 2 /-CHO molar ratio of 1, three kinds of dynamic covalent imine copolymer amphiphiles D m -HC n A, D m -HC n DA and D m -FC n A were generated in water in situ, respectively, attributing to the formed imine bonds between the aldehyde and amino precursors. D m -HC n As commonly form spherical micelles as well as D m themselves. Instead, D m -HC n DAs prefer to form squiggly threadlike micelles composed of randomly connected and fused spherical micelles. For D m -HC n As and D m -HC n DAs both m and n affect the micellar morphologies slightly, however, showing remarkable effect on D m -FC n A micelles. Specifically, D 3 -FC n As tend to form spherical micelles. D 13 -FC n As and D 24 -FC n As tend to form cylindrical micelles, and the micellar length becomes elongate at the larger m or n as well as classic copolymer amphiphiles. These dynamic covalent imine copolymer micelles are all excellent Pickering emulsifies, which commonly favor O/W Pickering emulsions as evidenced by the confocal laser scanning microscopy (CLSM) method. However, D m -HC n As with larger n , i.e. , D 13 -HC 16 A and D 24 -HC 16 A, also behave diversified emulsification that W/O/W or even W/O emulsions might be generated at the higher emulsification shear rates. It was found that the strong hydrophobicity and good compatibility with oil of them were the main cause.