Formation of macrocyclic polymers by intramolecular coupling of α,ω‐difunctional precursors. Numerical evaluations

Abstract

The end-to-end cyclization reaction of living monodisperse a,o-dianion precursors with difunctional electrophiles (EX,) in the presence of partial anion termination is described. A computer simulation was developed to establish the relationship among the initial concentration, the molecular weight of the dianion precursor, the extent of anion termination, and the yield distribution for all of the cyclic and linear polymer species. A master curve is calculated allowing the determination of the macrocycle yield as a function of MW and concentration of the dianion precursor, and degree of anion termination.

Synthesis and characterization of macrocyclic poly(.-methylstyrene)

“…2) [23]. The peak at about 12.1 ml corresponds to that of the cyclic dimer and is more prominent than for The ratio of linear and cyclic polymers in the remaining broad multimodal MW distribution mixture depends on the overall degree of termination of the functional groups involved in the coupling reactions and on the number of coupling reactions giving rise to a particular high MW polymer [23].…”

“…Even at 30 % overall loss of functionality the resulting probability for precursor anion termination at both chain ends would be on the order of only 10 %. Under such conditions large amounts of higher MW linear polymers are formed [23] but these can be removed via fractional precipitation and the remaining cycles should be substantially free of linear contaminants. Scheme 1.…”

“…2) [23]. The peak at about 12.1 ml corresponds to that of the cyclic dimer and is more prominent than for The ratio of linear and cyclic polymers in the remaining broad multimodal MW distribution mixture depends on the overall degree of termination of the functional groups involved in the coupling reactions and on the number of coupling reactions giving rise to a particular high MW polymer [23]. Thus the proportion of linear polymers in the high MW fraction increases sharply with the degree of anion termination and with the number of coupling reactions as the chance of termination increases with the number of such reactions [23].…”

Synthesis and characterization of macrocyclic vinyl aromatic polymers

“…24 Thus, the highest MW fraction of the polycondensate is more likely to be linear than the lower MW coupling polymers.…”

Synthesis and thermal and spectroscopic properties of macrocyclic vinyl aromatic polymers

“…The presence of macrocyclic P2VN, the very similar shapes for the linear and macrocyclic P2VN, and the presence of a significant fraction of the macrocyclic polymer dimer show an interesting tendency, consistent with predictions, to form macrocyclic P2VN even at relatively high anion concentrations (2 ϫ 10 Ϫ3 -3 ϫ 10 Ϫ3 M). 33,34 The number-average molecular weight (M n ) of the highest MW fraction (M n ϭ 101,600) indicates a high efficiency of coupling as this MW is 17 times that of the linear precursor (Table 1).…”