Department of Controlled Polymerization

Head: Petr Vlček, DSc

(phone +420-296 809 250, e-mail vlcek@imc.cas.cz)

Research

Activities of the Department comprise methods of controlled polymer synthesis using ionic and radical processes and preparation of tailor-made polymers and copolymers with predetermined parameters, based mostly on polar and non-polar vinyl monomers.

1. Anionic polymerization of acrylic and methacrylic esters is investigated, initiated with complex initiating systems (ligated anionic polymerization, LAP), for which an original initiating complex has been developed, leading to so called "living" polymerization. The method gives polymers with well-defined and adjustable parameters, for instance length and microstructure of chains and to block and graft copolymers with controllable length and chemical structure of the blocks. Using model systems, the mechanism and chemism of individual steps of the polymerization process are studied as well as the relation between the chemical structure of initiating complexes and their initiating efficiency. The block and graft copolymers can be used in a number of technologies, like compatibilization of polymer blends or highly efficient stabilization of aqueous and non-aqueous dispersions, used in manufacture of waterborn paintings and lacquers.

2. The modern controlled radical polymerization is studied (atom-transfer radical polymerization, ATRP), which is, compared with ionic processes, simpler and less expensive and, consequently, more advantageous in technological applications. Novel initiating systems and multifunctional macroinitiators for tailoring of copolymers have been designed, giving graft, block and comb copolymers of various molecular parameters and chemical compositions. Thus, precursors of amphiphilic tri- and multiblock copolymers were synthesized with hydrophilic and hydrophobic blocks, which can be used as steric surfactants in a number of technologies. Further, preparation of thin polymer films anchored on solid substrates is under development, applicable, e.g. in protein separation.

3. Attention is also paid to cationic polymerization of isobutylene, styrene and its derivatives, using an original initiating system, allowing to polymerize the monomers even at elevated temperatures. Polyisobutylene macromonomers, block and graft copolymers and reactive polymers with various functional groups can be prepared in this way. Synthesis of amphiphilic copolymers containing polyisobutylene chains is intensively studied, using a combination of cationic and radical processes. Among others, these products are applicable in biomedicine, for instance as materials for various implants. Graft copolymers with polyisobutylene backbone and chemically different grafts can be also prepared in this way; they can be used as compatibilizers of polymer blends, containing butyl rubber or polyolefins.

4. Further, controlled radical polymerization (ATRP) is used in development of novel polymer materials based on polymers from renewable sources, so called "green" polymers. Cellulose and/or its derivatives are the starting raw-materials here. In the first case, cellulose particles are surface-grafted using ATRP with various monomers, giving cellulose fillers for polymer composites with controllable adhesion at the interface. The composites can be used, e.g. as insulating materials in a number of technologies. Grafting of cellulose derivatives (esters, ethers) gives novel graft copolymers with cellulose backbone and chemically various grafts, which impart required application properties into the material. Controlled graft copolymerization makes it possible to modify density, molecular parameters and chemical composition of the grafts, giving thus a wide scale of materials.

Send your comments to: vlcek@imc.cas.cz
Last modified: 08.12.2004