Evandro M. Alexandrino

Unsaturated poly(phosphoester)s via ring-opening metathesis polymerization

For the first time, ring-opening metathesis polymerization of novel 7-membered cyclic phosphate monomers and their copolymerization with cyclooctene is presented. The monomers were investigated with respect to their metathesis behavior with different Grubbs catalysts and it was found that the Grubbs third generation catalyst gives the best results resulting in polymers with a molecular weight of up to 5000 g mol−1. Also copolymers with cyclooctene (up to a molecular weight of ca. 50 000 g mol−1) were synthesized and the monomer ratios were varied. The degree of polymerization could be controlled and the polydispersity index was usually below two. Acidic hydrolysis of the copolymer showed a complete shift of the molecular weight distribution to higher elution times in SEC, indicating a random incorporation into the poly(cyclooctene) backbone of the phosphate monomers and the possible degradation of the phosphate bonds along the backbone. Further, potentially degradable nanoparticles were prepared by a solvent evaporation miniemulsion technique.

Reactions and Polymerizations at the Liquid-Liquid Interface

Reactions and polymerizations at the interface of two immiscible liquids are reviewed. The confinement of two reactants at the interface to form a new product can be advantageous in terms of improved reaction kinetics, higher yields, and selectivity. The presence of the liquid-liquid interface can accelerate the reaction, or a phase-transfer catalyst is employed to draw the reaction in one phase of choice. Furthermore, the use of immiscible systems, e.g., in emulsions, offers an easy means of efficient product separation and heat dissipation. A general overview on low molecular weight organic chemistry is given, and the applications of heterophase polymerization, occurring at or in proximity of the interface, (mostly) in emulsions are presented. This strategy can be used for the efficient production of nano- and microcarriers for various applications.