Polymeric nanosphere formed from temperature-responsive polymer composed of (N,N-dimethylamino)ethyl methacrylate and ethyl acrylamide

A nanosphere was formed from a temperature-responsive random copolymer of ( N,N-dimethylamino)ethyl methacrylate (DMAEMA) and ethyl acrylamide (EAAm) w ithout a crosslinker. When the copolymerization was performed in a water/et hanol solvent mixture (90/10 v/v %) above the lower critical-solution tempe rature of poly(DMAEMA-co-EAAm), the nanosphere was formed with the propagat ion of copolymerization. Atomic force microscopy analysis and dynamic light scattering both showed the formation of nanosphere and the size was decrea sed as the EAAm content increased in the copolymer. To illuminate this nano sphere formation phenomena, molecular dynamic simulations were performed wi th model polymer solutions. According to the analysis of the simulation tra jectory, the ethyl groups of ethanol bind to the hydrophobic sites of poly( DMAEMA) or poly(DMAEMA-co-EAAm), and water molecules can bind preferentiall y to C=O groups that are abundant on the surface of the core, which is comp osed of oligomer and ethanol. This may enable the polymerization to proceed within the core, which is transformed into nanosphere. (C) 2001 John Wiley & Sons, Inc.