Synthesis and characterization of synthetic polymer colloids colloidally stabilized by cationized starch oligomers

A method is developed for anchoring enzymatically degraded cationized starch as electrosteric stabilizers onto synthetic latices, using cerium(IV) to create free radical grafting sites on the starch. Direct anchoring of debranched starch onto a poly (methyl methacrylate) seed latex yields a latex stabilized by well-defined oligosaccharides. Using α-amylase to randomly cleave starch to form (1→4)-α-glucans, and a comonomer, N-isopropyl acrylamide (NIPAM), whose corresponding polymer exhibits a lower critical solution temperature (LCST), creates a means to synthesize block (or graft) oligomers of oligosaccharide and synthetic polymer, which are water soluble at room temperature. Above 30 degrees C, they become amphiphilic and form self-emulsifying nanoparticles (sometimes termed ‘‘frozen micelles’’) from which a synthetic latex is grown after addition of methyl methacrylate, the collapsed NIPAM-containing entities functioning as a type of in situ seed. This synthesis of stable synthetic latex particles is shown to have a high grafting efficiency. The starch fragments were characterized by 1H solution state NMR before grafting, and 13C solid-state cross-polarization magic-angle spinning (CP-MAS) NMR was used to characterize the starch oligomers actually grafted on the final latex.