Cyclolinear polysiloxanes. I. Synthesis and characterization

Abstract

The synthesis and characterization of two novel cyclic siloxanes, diacetoxydiethyltetramethylcyclotetrasiloxane and diacetoxytriethylpentamethylcyclopentasiloxane, and cyclolinear polymers synthesized from these monomers are presented. The cyclic siloxanes were synthesized from tetramethylcyclotetrasiloxane and pentamethylcyclopentasiloxane, respectively, by acetylation followed by ethylation. The cyclic monomers were characterized with 1 H NMR spectroscopy. Subsequently, the cyclic siloxanes were self-condensed into cyclolinear polysiloxanes and cocondensed (extended) with silanol-terminated polydimethylsiloxane into high-molecular-weight polymers containing cyclic units with linear polydimethylsiloxane spacers (extended cyclolinear polysiloxanes). The molecular weights of both the cyclolinear polysiloxanes and extended cyclolinear polysiloxanes were determined.

Cyclolinear polysiloxanes. II. Crosslinking and characterization

“…Toluene and tetrahydrofuran were from Aldrich. The syntheses of CLPSs and eCLPSs were described in the previous article 1…”

“…Before injection, solutions were filtered through a 0.45-lm Teflon syringe filter. 1 H NMR spectroscopy was carried out with a Varian Gemini-300 spectrometer. The sample concentration was $30 mg/0.75 mL in CDCl 3 in a 5-mm sample tube.…”

“…The first part of this series of publications concerned the synthesis and characterization of two novel bifunctional cyclosiloxane monomers, diacetoxydiethyltetramethylcyclotetrasiloxane (D 4 Et 2 OAc 2 ) and diacetoxytriethylpentamethylcyclopentasiloxane (D 5 Et 3 OAc 2 ), their polymerization by self‐condensation, and cocondensation with silanol‐terminated polydimethylsiloxane (PDMS) 1. Figure 1 summarizes the structures of these monomers and the cyclolinear polysiloxanes (CLPSs) prepared from them.…”

A novel approach for anionic bulk polymerization of 1,3,5‐tris(trifluoropropylmethyl)cyclotrisiloxane

“…As discussed by Clarson et al [26, 27], the linear polydimethylsiloxane (PDMS) is degraded by the chain scission of an intramolecular cyclic transition state, resulting in the formation of the volatile cyclics, oligomers, and silica. To understand the degradation mechanism of PMTFPS, the degradation kinetic analysis was investigated.…”

Unraveling the architecture of plasma polymers by electrospray tandem mass spectrometry

“…Since the 228 Si=O group is unlikely to exist in condensed matter, occurrence of cycles within the oligomer 229 backbone was considered in lieu of double bonds. At that point, a nomenclature had to be 230 developed to designate these PDMS oligomers based on the extended cyclolinear polysiloxanes 231 (eCLP) representation [42]. Plasma oligomers were named k C i (α,ω), with the superscripted k − (hydro, hydroxy)-polysiloxanes, generated from segments between cross-links (Scheme 1, i), 245…”