Interaction of Comb-Type Copolymers with Long Chain Paraffin in Oil Observed By Epifluorescence Microscopy

Interactions between copolymer additives (maleic alkylamide and alpha-octadecene copolymers: MAC, AMAC, and NMAC) with different functional groups with long chain paraffin crystals in waxy model oils have been systematically investigated by epifluorescence optical microscopy. Ultraviolet (UV) and blue light (495 nm) were applied in this experiment. Both long chain paraffin crystals and the assembled polymers were found glowing blue with UV illumination, while the polymers emitted stronger yellow-green fluorescence light than crystals in blue light field. MAC, which has long paraffinic lateral chains, was found to be capable of changing the shape of wax crystals from granule-like into sharp needle-like, implying a co-crystallization mechanism in the wax forming process. Copolymers with aromatic groups on their backbones (AMAC and NMAC) were observed to behave in different ways from MAC. NMAC, which contains naphthalene groups and glowed deep yellow fluorescence light in blue light field, seems to be merely absorbed on the surface of wax crystal. AMAC, which has benzene groups, appeared to self-crystallize separately from wax and its aggregations were found inclined to adhere the wax crystals and even functioned as the center of gathering waxes. Epifluorescence microscopy method provides a new perspective to acquire an insight into the distribution of polymer additives, the assembly mechanism, and their effects on modifying the morphology of long chain paraffin crystals in waxy oil.