Polystyrene/polybutadiene nanoparticles with low environmental impact. Analysis of post-polymerization strategies

RONCO, LUDMILA I.; MINARI, ROQUE J.; GUGLIOTTA, LUIS M.

Dresden

Congreso; European Polymer Congress 2015; 2015

European Polymer Federation

The incorporation of polybutadiene (PB) in waterborne polystyrene (PS) nanoparticles by miniemulsion polymerization was studied to positive combine the properties of both components, improving the toughness of the vitreous material [1]. Unfortunately, the polymerization did not proceed to completion, and there was an inevitably high level of unreacted monomer in the polymer [1]. Therefore, this work addresses the implementation of different post-treatment methods to remove the residual styrene (St) from high solid content (50%) PB/PS latexes. Latexes were synthesized by miniemulsion polymerization using potassium persulfate (KPS) and benzoyl peroxide (BPO) as initiators [1]. When post-polymerizations were carried out by additionally dosing the redox initiators tert-butyl hydroperoxide (TBHP)/ascorbic acid (AsAc), the residual St was significantly reduced (below 250 ppm). Unfortunately, with this strategy new Volatile Organic Compounds (VOCs) were formed. On the other hand, a post-polymerization method based on the St thermal initiation (at 130 ºC) proved being efficient to considerably reduce the residual St (below 330 ppm), thus avoiding both the use of additional initiators and the formation of new VOCs. While post-treatments did not affect the morphology of hybrid polymer particles and of the final material, the amount of grafted PS and gel content were significantly increased. This increment on the gel content adversely affected the tensile properties of the hybrid materials, reducing their toughness [1]L.I. Ronco, R.J. Minari, M.C.G. Passeggi Jr., G.R. Meira, L.M. Gugliotta Chem Eng. J. 2015, 263, 231.