Polymerization of hexamethylcyclotrisiloxane with a biscatecholsiliconate. II. Kinetics of polymerization

Abstract

The kinetics of polymerization were investigated for the polymerization of hexamethylcyclotrisiloxane (D3) in toluene with methanol or water as an initiator, benzyltrimethylammonium bis(o‐phenylenedioxy)phenylsiliconate as a catalyst, and dimethyl sulfoxide (DMSO) as a promoter. The rate of initiation was found to be comparable with both water and methanol. Addition of catechol drastically reduces the rate of initiation. The rate of propagation was found to be dependent upon the catalyst, DMSO, catechol and the aging of the catalyst solution. Two types of functional groups were postulated to be present during the propagation reaction, i.e., SiOH (dormant form) and SiONR4 (living form). The former can be converted to the latter by R4NOH derived from hydrolysis of catalyst. A postulated mechanism of polymerization with biscatecholsiliconate is presented.

Dynamic light scattering from swollen poly(dimethylsiloxane) networks

“…This agreement is surprising, at first, in view of the higher concentrations of our solutions and networks (u2 0.2). However, one can keep the higher order corrections (u23 terms) to eqs [18][19][20] by taking into account the concentration dependence of reported earlier. 1 We find that because these corrections appear in both numerators and denominators on the right-hand side of eq 17, their effect is not appreciable.…”

“…To prepare the networks, the required amount of B2, Bi, and A4 was first diluted with toluene to a PDMS volume fraction of 0.10 and stirred overnight. The end-linking reaction was catalyzed with cts-dichlorobis(diethyl sulfide)platinum(II) in toluene to achieve a concentration of 20 parts platinum/106 parts PDMS. After the addition of the catalyst, each sample was filtered through 0.20-gm FP-Vericel syringe filters into glass vials which had been rinsed with filtered toluene.…”

End-Linked Poly(dimethylsiloxane) Elastomer Structure: 2H-NMR Transverse Dephasing Data Compared to Predictions of Statistical and Thermodynamic Models

“…13 B2 and B1 were produced by polymerizing hexamethylcyclotrisiloxane (D3), using insertion polymerization techniques developed to minimize polydispersity and branching. [14][15][16] B2 was produced by polymerizing D3 in toluene, using water as an initiator, dimethyl sulfoxide (DMSO) as a promoter, and benzyltrimethylammonium bis(o-phenylenedioxy)phenylsiliconate as a catalyst. B1 was produced by polymerizing D3 in cyclohexane, using n-BuLi as an initiator and DMSO as a promoter.…”

Sequence distribution in poly(dimethylsiloxane-co-methylvinylsiloxanes)

“…Numbering for V units begins at V adjacent to D unit. 6 Sample contaminated with about 15% MDVDM. conditions allowed quantitative integration.…”