Block copolymers and telechelic oligomers bearing methacrylate moities were obtained by means of a new highly selective end group reaction. Starting from polymethacrylates that were prepared by radical polymerization in the presence of mercaptanes as chain transfer agents, the resulting ester end group linked to the terminal tertiary carbon atom of the polymer backbone can be either transesterified or saponified selectively. The selectivity of the end group reactions was determined by MALDI‐TOF‐mass spectrometry. Polymethacrylate‐b‐poly(ethylene oxide)‐, polymethacrylate‐b‐poly(methacrylic acid)‐ and polymethacrylate‐b‐polysiloxane‐b‐polymethacrylate‐copolymers as well as α,ω‐dihydroxy‐ and α,ω‐dicarboxy‐telechelic polymethacrylates were prepared by applying end group transesterification or end group saponification.
The radiation-induced polymerization of styrene, methyl methacrylate, and vinyl acetate containing small amounts of triethyl borate has been studied. At the same absorbed dose rate, the rate of polymerization by the high LET particles from the reaction B10(n,a)Li7 was found to be much lower than by -rays, while the average molecular weight of the polymer formed was higher. The results are explained by assuming that only free radicals in the tracks of fast -electrons are able to initiate long-chain polymerization. The fraction / of the energy of the heavy particles that is effective in producing polymerization amounts to 0.16 for styrene, 0.09 for methyl methacrylate, and 0.04 for vinyl acetate (if / is made equal to unity in the case of -rays). It is shown that / decreases with increasing radiation sensitivity (G(R) value) of a monomer.The minimum kinetic energy of the -electrons which participate in the initiation of long-chain polymerization is calculated to be 170-240 e.v., depending on the nature of the monomer.
Die Darstellung verszhiedener 2-Alkoxymethyl-A2-imidazoline und -Az-tetrahydropyrimidine aus den entsprechenden Alkoxyacetaten und Alkoxyacetarniden sowie aus Dia-halogenathern wird beschrieben.Die 2-substituierten A2-Imidazoline haben rnit verschiedenen 2-Arylmethyl-Derivaten einen festen Platz in der Reihe der Syrnpathikomimetika erlangt. Je nach der
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