Addition of hydrogen iodide to isobutyl vinyl ether (1) yields l-(l-iodoethoxy)-2-methylpropane (2). The cationic polymerization of 1 initiated by 2/tetraalkylammonium salts (R,N+A-) shows the characteristics of a living polymerization. Different tetraalkylammonium salts were investigated. The coinitiator R4N+A-has no effect on the molar mass and the molar mass distribution of the resulting polymers. However, the rate of polymerization depends heavily on the nature and concentration of the coinitiator. The effect of the coinitiator is discussed on the basis of a special salt effect.
Abstract:The cationic polymerization of vinyl ethers initiated by CH3-CH(OR)(I) /%N+A-(R = Alkyl, A-= ClO4-. BF4-, PF6-. I-. NO -shows the characteristics of a living polymerization. The rate of polymerization is a function of the solvent polarity, the temperature, the type and concentration of the ammonium salt. The experimental data can be explained on the basis of the secondary salt effect overlapped by some dipol-dipol interactions of the chain end and the added salt. Functionalization of the chain end with thermolabile azo functions yields polymeric initiator which was applied for the synthesis of blockcopolymers. Vinyl ethers functionalized with furylacrylic ester groups were polymerized and crosslinked via [ 2 + 2 ] cycloaddition.
Scope and limitation of the vinyl ether polymerization initiated by NR4ClO4(KClO4;LiClO4)/CH3CHI‐OR was discussed. Besides isobutyl vinyl ether (IBVE), N‐vinylcarbazole (NVC) and 2‐chloroethyl vinyl ether (CEVE) were initiated by NR4ClO4/CH3CHI‐OR. These polymerizations exhibited the characteristics of a living polymerization. However, in order to observe narrow molar mass distribution NVC was initiated with CH3CHI‐OR, without salts. Block copolymers were synthesized by the method of sequential monomer addition (NVC, IBVE, CEVE). The PCEVE segment was modified by nucleophilic substitution, which allowed the synthesis of amphiphilic block copolymers.
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