Environmental aspects of controlled radical polymerization

摘要

Controlled radical polymerization is an important recent development in polymer synthesis with a potential strong impact on various environmental aspects. This technique enables facile preparation of novel environmentally friendly materials such as polar thermoplastic elastomers, coatings with the reduced amount of VOCs or even solventless coatings and several other specialty materials such as efficient non-ionic surfactants, dispersants, lubricants, adhesives, etc. The controlled radical polymerizations have been successfully performed in bulk or in water and require only a modest deoxygenation of the reaction mixtures. These polymerizations have been applied to homogeneous systems and also to emulsions, dispersions and suspensions. Atom transfer radical polymerization is one of the most efficient methods to control radical polymerization in the presence of various transition metal complexes. Development of new more efficient catalytic systems enables reduction of the amount of catalysts and their recycling. Use of ligands which better stabilize higher oxidation state metal compounds, such as linear and branched aliphatic polyamines, allowed a significant reduction of the catalyst concentration in comparison with the originally used bipyridine complexes. Immobilization of catalysts enables their efficient reclamation but is accompanied by the formation of polymers with higher polydispersities than in the homogeneous systems.