New polymer structures based on vinyl ether polymerization

Sequential living cationic polymerization of octadecyl vinyl ether (ODVE) a nd methyl vinyl ether (MVE) was used for the preparation of amphiphilic ABA -type block copolymers. The polymerization of ODVE was initiated with the t rimethyl silyl iodide/1,1,3,3-tetramethoxy propane/ZnI2 system at 0 degrees C in toluene. The living bifunctional polyODVE thus obtained was used as i nitiator for the polymerization of MVE. Below the LCST of polyMVE (37 degre es C), the copolymers are amphiphiles. Above the LCST of polyMVE, the polyM VE-blocks become hydrophobic and the amphiphilic nature of the block copoly mer is lost. This was demonstrated by using the block copolymers as emulsif iers for water/decane mixtures. The emulsions were stable for several hours at room temperature, while the emulsion stability decreased to about 30 se conds at 40 degrees C. PolyMVE-alpha,omega-bis-methacrylates were obtained by end-capping of livin g bifunctional polyMVE with 2-hydroxyethyl methacrylate (HEMA). Copolymeriz ation of these bis-macromers with HEMA leads to segmented networks. The net works showed a reversible swelling/deswelling behavior in water as a functi on of temperature. This is caused by a change of the hydrophilicity of the polyMVE segments in the networks. Hexa(chloromethyl)melamine, combined with zinc chloride was found to be an efficient hexafunctional initiator for the living cationic polymerization o f vinyl ethers. This simple initiating system opens new ways for the synthe sis of endgroup-functionalized star-shaped poly(vinyl ethers).