Effects of crosslinker on the morphology and properties of microgels containing N-vinylformamide, glycidylmethacrylate and vinylamine.

Microgels are swollen crosslinked polymer colloid particles. We used non-aqueous dispersion polymerisation to prepare new water-swellable microgels containing N-vinylformamide (NVF), glycidylmethacrylate (GMA) and an alkali-stable crosslinker, 2-(N-vinylformamido)ethyl ether (NVE). The microgel particles had a core that was rich in NVF. The shell contained GMA and NVF. In order to expose the amine functionality, alkaline hydrolysis was used, transforming the NVF groups in the shell to vinylamine (VAM) while leaving most NVF in the core untouched. The hydrolysed microgels (H-NVF-GMA-NVE) were cationic at low pH and were shown to have polyampholyte behaviour. Inclusion of NVE had the beneficial effects of preventing microphase separation at the microgel surface and stabilising the polyampholyte structure against excessive fragmentation during hydrolysis. These new water-swellable core-shell microgels were prepared using scalable methods and may enable future preparation of functionalised core-shell microgels and composites.