The living cationic polymerization of vinyl ethers has been used to prepare a number of new polymers with special properties. Sequential polymerization of the hydrophilic methyl vinyl ether (MVE) and the hydrophobic octadecyl vinyl ether (ODVE) has lead to amphiphilic block‐copolymers with emulsifying properties for water/decane mixtures. Poly(vinyl‐ether) macromonomers were obtained by end‐capping of living polymers with hydroxyethyl acrylate. Copolymerization of polyODVE‐macromonomer with usual acrylates lead to highly branched hydrophobic polymers. When the end‐capping was performed with bifunctionally living polymers, the corresponding “bis‐macromonomers” were obtained. Copolymerization of such bis‐macromonomers with styrene or butyl acrylate, leads to the formation of segmented polymer networks. In the case of polyODVE‐poly(butyl acrylate), these networks showed a pronounced phase separation. Due to the crystallinity of the polyODVE domains, these materials showed shape memory properties.
EPDM (ethylene-propylene rubber) has been used for more than 25 years as the main elastomer in radiator hoses because it offers a well-balanced price/performance ratio in this field of application. Some years ago the automotive and rubber industry became aware of a problem called electrochemical degradation and cracking. Cooling systems broke down due to a typical cracking failure of some radiator hoses. Different test methods were developed to simulate and solve the problem on laboratory scale. The influence of different variables with respect to the electrochemical degradation process has been investigated, but until recently the influence of the engine coolant was ignored. Using a test method developed by DSM elastomers, the influence of the composition of the engine coolant as well as of the EPDM composition has now been evaluated. This paper gives an overview of test results with different coolant technologies and offers a plausible explanation of the degradation mechanisms as a function of the elastomer composition.
Block copolymers consisting of methyl vinyl ether (MeVE) units and octadecyl vinyl ether (ODVE) units were synthesized using the cationic living polymerization technique. The polymerization of MeVE was initiated with the trimethyl silyl iodide/1,1‐diethoxyethane/ZnI2 system at −40°C in toluene and the living polymer thus obtained was used as initiator for the polymerization of ODVE at 07deg;C. The combination of hydrophilic (PMeVE) and hydrophobic (PODVE) segments provides the block copolymers with non‐ionic surfactant properties, which have been evaluated by measurement of the stabilities of water–decane emulsions.
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