Emulsion ATRP of methyl methacrylate/2-ethylhexyl methacrylate and morphological and adhesion properties of the latex

Emulsion Atom transfer radical polymerization (ATRP) is a novel polymerization route that can produce polymers with well-controlled structure and molecular weight. It has been used to synthesize block copolymers with linear, star shaped, or dendrite type structures. The product is a latex with low viscosity. The process has good heat transfer and mixing. It can yield high conversion for the first block that is well suited for stepwise block copolymerization. Emulsion ATRP has monomer versatility and there is no need for expensive monomer and solvent purification units. In this thesis work, we have applied this technique, to block copolymerization of triblock copolymers of 2-ethylhexyl methacrylate (EHMA) (middle block) and methyl methacrylate (MMA).;The conditions for the best stability were further utilized for the synthesis of block copolymers of MMA and EHMA, and different sets of these copolymers were synthesized. These block copolymers were studied in detail. It was shown that individual particles have a core-shell morphology. The wetting properties of these particles and their relationships to the internal morphology of particles were studied. Thin solvent-cast films showed a typical block copolymer two-phase morphology. In latex-cast films, the cores of different particles merged during film formation and made bridges between them. The final films were coherent and pinhole free. The effect of annealing on the latex film morphology was studied. The peeling strengths of block copolymers were measured, and their dependence on the degrees of polymerization of blocks was determined. The P(MMA-EHMA-MMA) sample with DPn's of 310-930-310 without any added tackifier yielded the highest peeling strength of 7.4 kgf/in that is in the range of commercial adhesives containing tackifiers. The final copolymer is a thermoplastic elastomer and can be used as a candidate for applications in medical and toner industries as well as hot melt pressure sensitive adhesives.;This sandwich thesis is organized based on three refereed-journal papers first-authored by the candidate. A detailed study of homopolymerization of EHMA using emulsion ATRP was first presented. The effect of different parameters like temperature, monomer/initiator ratio, surfactant type and concentration and CuBr2 addition was studied and it was found possible to obtain stable system with well-controlled molecular weight using Tween 80 as the sole surfactant, ethyl 2-bromoisobutyrate (EBiB) as an initiator and copper bromide (CuBr)/4,4'-dinonyl-2,2'-bipyridyl (dNbpy) as a catalyst system at 30°C. This operational window was used for emulsion ATRP of EHMA using the same catalyst system and surfactant and 1,4-butylene glycol di(2-bromoisobutyrate) (BGDBiB) as a bifunctional initiator. The effects of monomer/initiator ratio and CuBr2 addition, and temperature profile were investigated.