High purity nanolatex prepared by ultrasonically irradiated emulsion polymerization.

Ultrasonically initiated emulsion copolymerization of styrene and a cationic polymerizable surfactant (methacryloxyethyl dodecydimethyl ammonium bromide, C(12)N(+)) was successfully employed to prepare high purity copolymer nanolatex. C(12)N(+) can play the roles of an emulsifier, an initiator, and a comonomer at the same time. It has an excellent initiation efficiency and reactivity. The rate of copolymerization was high and styrene conversion achieved 95% in an hour. Nanoscale latex particles with average diameter 40 nm were obtained easily under ultrasonic irradiation. Results of FTIR, (1)H NMR and surface tension tests proved almost all surfmers had copolymerized with styrene when the C(12)N(+) concentration was more than 0.030 g/mL, indicating high purity nanolatex without residual emulsifiers was obtained.

Radical generation process studies of the cationic surfactants in ultrasonically irradiated emulsion polymerization.

Without any chemical initiators added, ultrasonically irradiated emulsion copolymerization of styrene and a cationic polymerizable surfactant (methacryloxyethyl dodecydimethyl ammonium bromide, C(12)N(+)) was successfully employed to prepare copolymer nanolatexes. Compared with the conventional ionic surfactants, C(12)N(+) has much higher initiation efficiency and C(12)N(+) system exhibits shorter induction period, much higher styrene conversions and polymerization rate R(p) in short reaction time. A radical trapping experiment and gas chromatograph-mass spectrograph analysis proved that under ultrasonic irradiation, C(12)N(+) undergoes bond scission between the two alkyl and ionic group, where both C-N bonds are weak along the chain, thereby producing much more original radicals to initiate the emulsion polymerization.