Ultrafast Conversion and Molecular Weight Control through Temperature Programming in Microwave-Induced Miniemulsion Polymerization

Abstract

Microwave-mediated miniemulsion polymerization of styrene with consecutive periods of heating and cooling exhibits s compared to continuously heated polymerizations s a very unique behavior. For mediumhydrophobic azo-initiators under optimized conditions, polymer radicals survive the heating pulse and grow during the cooling period to ultrahigh molecular weights >10 7 g/mol. This "surviving radical effect" is accompanied by unexpectedly high conversion after the first polymerization cycle, comprising of a temperature pulse of less than 10 s duration and a subsequent cooling period. Besides the ultrarapid heating by the microwaves, the surviving radical effect is purely thermal in nature and can be explained by the elemental reactions of radical heterophase polymerizations.

Preparation and characterization of fluorinated acrylate copolymer latexes by miniemulsion polymerization under microwave irradiation

“…Holtze [32,33] and Zhu [34] have indeed conducted some research on the use of microwave irradiation in miniemulsion polymerization. Holtze [32,33] indicated that ultra-fast conversion and molecular weight could be obtained through temperature programming in microwave induced miniemulsion polymerization. In Zhu's work [34], well-defined and stable polystyrene latexes were obtained by nitroxide-mediated radical miniemulsion polymerization under microwave irradiation.…”

Polysiloxane nanoparticles prepared by emulsion polymerization under microwave irradiation

“…It is no wonder that the different responses of two phases to MI may cause some unexpected results in the emulsion system. Most of the studies on microwave-assisted polymerizations have been focused on the latex particles prepared from styrene [6][7][8][9], methyl methacrylate [10][11][12][13], and butyl acrylate [14] etc. The study on the emulsion polymerization of PSi under MI, however, is still lacking.…”

Green Polymer Synthesis: An Overview on Use of Microwave‐Irradiation

“…Holtze et al applied the short pulses of MW heating to prepare polystyrene through the emulsion polymerization. Under optimized conditions, this method led to high molecular weights and high monomer conversion after a short time [84]. In a recent study, the same group showed the suitability of this strategy for continuous-flow processing that allows a treatment of -10 L of emulsion per hour [85].…”