Copolymerization of trioxan with dioxolan
1964; Elsevier BV; Volume: 5; Linguagem: Inglês
10.1016/0032-3861(64)90161-2
ISSN1873-2291
Autores Tópico(s)Synthesis and properties of polymers
ResumoAbstract The authors have studied the bulk copolymerization of dioxolan with excess trioxan. The ∼Si ⊕ HSO 4 ⊖ complex was used as initiator. The copolymerization scheme is too complicated for an exact analysis; it was therefore simplified by making several assumptions which proved plausible in a subsequent check of theory against experiment. In the authors' opinion copolymerization takes place on active centres (∼trioxan+, ∼dioxolan+) which are of approximately the same activity or, in other words, addition of the monomeric unit of any type does not alter the quality of the active centre. Dioxolan enters the polymer chain during copolymerization more readily than trioxan. A comparison of the rates of polymerization of pure components leads to opposite results. A probable explanation of this is that the actual concentration of dioxolan in the neighbourhood of an active centre is higher than the analytical (overall) concentration. In terms of this view the active centres are preferentially solvated by dioxolan. Similar effects in other pairs of monomers in ionic copolymerization have been described in the literature. Quantitative data about solvation of active centres are not known. Solvation, however, influences the value of monomer reactivity ratios. The authors define the so-called ‘modified monomer reactivity ratios’ which make it possible to calculate the composition of the copolymer. The calculation has been verified experimentally in the range of low concentrations of dioxolan.
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