Encapsulated clay particles in polystyrene by RAFT mediated miniemulsion polymerization

Abstract

RAFT grafted montmorillonite (MMT) clays [i.e., N,N-dimethyl-N-(4-(((phenylcarbonothioyl)thio)methyl)benzyl)ethanammonium-MMT (PCDBAB-MMT) and N-(4-((((dodecylthio)carbonothioyl)thio)methyl)benzyl)-N,N-dimethylethanammonium-MMT (DCTBAB-MMT)] of various loadings were dispersed in styrene (S) monomer and the resultant mixtures emulsified and sonicated in the presence of a hydrophobe (hexadecane) into miniemulsions. The stable miniemulsions thus obtained were polymerized to yield encapsulated polystyrene-clay nanocomposites (PS-CNs). The molar mass and polydispersity index (PDI) of the PS-CNs depended on the amount of RAFT agent in the system, in accordance with the features of the RAFT process. The morphology of the PS-CNs ranged from partially exfoliated to an intercalated morphology, depending on the percentage clay loading. The thermomechanical properties of the PS-CNs were better than those of the neat PS polymer, and were dependent on the molar mass, PS-CN morphology and clay loading. The similarities and differences of the PS-CNs prepared here by miniemulsion polymerization were compared to those prepared using the same RAFT agents and polymer system by bulk polymerization (as reported by us in a previous article). V

Living Radical Polymerization by the RAFT Process - A Second Update

“…Other substrates to which the 'grafting-from' approach has been applied include silicon wafers, [179,213,524] poly(silsesquioxane), [210,228] [105] 408 [142] (POSS), [350,360,361] indium-tin oxide (ITO) surfaces, [176] carbon nanotubes, [525] titania particles, [526,527] clay, [528][529][530] cadmium sulfide nanoparticles, [531] cellulose, [532][533][534][535] and PVDF membranes. [536] …”

Attapulgite grafted with polystyrene via a simultaneous reverse and normal initiation atom transfer radical polymerization

“…Therefore, decreasing radical concentration can directly affect the polymerization rate and monomer conversion. 30 These unreacted functionalities as impurities can increase chain transfer and termination of propagating radicals and disturb the equilibrium of ATRP reaction, which leads to higher polydispersity values.…”

In situ Synthesis of Polymer/Clay Nanocomposites by Living and Controlled/Living Polymerization

“…Later, Zhang et al [25] used the in situ RAFT polymerization with an intercalated RAFT agent to produce polystyrene/MMT nanocomposites with exfoliated structure and higher thermal stability compared to pure polystyrene. Hartmann et al [45,46] have also shown the effectiveness of intercalated RAFT agents on the control of polymerization in bulk and miniemulsion during PCNs synthesis. The effect of clay loadings for the preparation of nanocomposites has been reported by Ding et al [26] who found exfoliated or intercalated structures, based on the different clay loadings.…”