A novel approach to conducting controlled free radical polymerization in water-borne organic dispersions using reversible addition-fragmentation chain transfer (RAFT) has been studied. The novel approach in this study focused on eliminating monomer and oligomer transport and comprised two fundamental steps: the synthesis of dithiobenzoate-end-capped styrene oligomers in bulk followed by emulsification of these oligomers to yield a polymerizable water-borne dispersion. Dithioesters that act as chain transfer agents in the RAFT process were synthesized in situ. The free radical polymerization of the dithiobenzoate-end-capped styrene oligomers in the water-borne organic dispersion proceeded in a controlled manner; molar mass increased in a linear fashion with increasing conversion, while polydispersities remained low. The familiar red layer formation associated with RAFT polymerization in conventional emulsions was not observed under these conditions. The effects of changing the costabilizer (hydrophobe) and the degree of polymerization of the emulsified oligomers were investigated. Better control was achieved with a less hydrophilic costabilizer and for the shorter of the oligomers tested.

The effect of various reducing monosaccharides on the rate of atom transfer radical polymerization (ATRP) of butyl methacrylate is reported in this study. The addition of reducing sugars affects the rate of ATRP positively with a 100% increase in the rate of polymerization in some cases. In addition, these organic reducing agents have little effect on the molecular weight and molecular weight distribution of poly(butyl methacrylate) with polydispersity indexes that remain well below 1.2. A possible explanation for these observations is the ability of the reducing sugars to reduce part of the Cu2+ species, which deactivate the growing radicals, to Cu1+, thereby ensuring a shift in the equilibrium between active and dormant chains in the direction of the former with a resulting increase in the rate of reaction.

Homogeneous tandem catalysis involving a highly selective, aluminoxane-activated bis(2-decylthioethyl)amine·CrCl3 complex for the synthesis of 1-hexene in tandem with a number of metallocene catalysts is discussed. Analysis by means of DSC, CRYSTAF, HT-GPC, 13C NMR, and FTIR suggests that copolymers of 1-hexene and ethylene are produced with significant selectivity toward 1-hexene as comonomer. The selectivity of 1-hexene incorporation by the metallocene catalysts follows the trend in the order [Me2Si(2-Me-Ind)2]ZrCl2 > [Me2Si(2,3,4,5-Me-Cp)(t-Bu-N)]TiCl2 > Cp2ZrCl2. The highly selective nature of the ethylene trimerization catalyst employed in this study means that the industrial application of tandem catalysis is becoming increasingly viable since it approaches conventional 1-hexene LLDPE in terms of polymer microstructure control.

Model alkali-soluble rheology modifiers of different molar masses were synthesized by the reversible addition-fragmentation chain-transfer polymerization of methyl methacrylate, methacrylic acid, and two different associative macromonomers. The polymerization kinetics showed good living character including well-controlled molar mass, molar mass linearly increasing with conversion, and the ability to chainextend by forming an AB block copolymer. The steady-shear and dynamic properties of a core-shell emulsion, thickened with the different model alkali-soluble rheology modifiers, were measured at constant pH and temperature. The steady-shear data for latex solutions with conventional rheology modifiers exhibited the expected thickening, whereas the associative rheology modifiers showed contrasting rheology behavior. The dynamic measurements revealed that the latex solutions thickened with the conventional rheology modifiers exhibit solid-like (dominant GЈ) behavior as compared with the associative rheology modifiers that give the latex solution a liquid-like (dominant GЉ) character.