The comonomer

N-isopropylacrylamide(NIPAAm)

was introduced in the system for synthesis of nanocapules through styrene miniemulsion polymerization by using low molecular weight hydrocarbon as template.The oligomers of poly(N-isopropylacrylamide) dehydrated and separated from water were adsorbed by the droplets of styrene miniemulsion.Due to the thermodynamic force and electrostatic interaction

the oligomer radicals of PNIPAAm anchoring at the interface of droplets make the interface to be the locus of polymerization.Monomers diffused from the internal part of droplets to supply for further polymerization.The nanocapsules can be obtained through the encapsulation of hydrocarbon by the newly-produced polymers separating at the interface of droplets.The morphologies were observed by TEM.The surface tension of miniemusion was measured by a contact angle determinator.The influences on the morphologies of final product such as the amount of NIPAAm

the ratio of monomer and hydrocarbon

the amount of crosslinking agent and the kinds of emulsifier and initiator pair were studied.The results with different amounts of NIPAAm showed that the homogenous nucleation was induced by the excess amount of NIPAAm which was unfavorable to form nanocapsules.With the increase of oil monomer/hydrocarbon ratio the amount of solid particles increased because the solubility of the NIPAAm in the droplets increased which resulted in the formation of solid particles.The nanocapsules with stable shells were obtained through introducing an appropriate amount of DVB.The entry of the oligomer radicals into nanocapsules was influenced by the initiator/surfactant pair depending on the protection ability of surfactants

the steric hindrance of the ionic groups of the surfactant or the electrostatic repellence.