When Attempting Chain Extension, Even Without Solvent, It Is Not Possible to Avoid Chojnowski Metathesis Giving D3.
Molecules
; 26(1)2021 Jan 05.
Article
en En
| MEDLINE
| ID: mdl-33466286
ABSTRACT
A simple, mild and efficient method to prepare HSi- or HOSi-telechelic, high-molecular-weight polydimethylsiloxane polymers (to 41,600 g·mol-1) using the one-shot hydrolysis of MHMH is reported; titration of the water allowed for higher molecular weights (to 153,900 g·mol-1). The "living" character of the chain extension processes was demonstrated by adding a small portion of MHMH and B(C6F5)3 (BCF) to a first formed polymer, which led to a ~2-fold, second growth in molecular weight. The heterogeneous reaction reached completion in less than 30 min, much less in some cases, regardless of whether it was performed neat or 50 wt% in dry toluene; homogeneous reactions in toluene were much slower. The process does not involve traditional redistribution, as judged by the low quantities (<3%) of D4 produced. However, it is not possible to avoid Chojnowski metathesis from MHDDMH giving D3, which occurs competitively with chain extension.
Palabras clave
Texto completo:
1
Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Polímeros
/
Solventes
/
Dimetilpolisiloxanos
Idioma:
En
Revista:
Molecules
Asunto de la revista:
BIOLOGIA
Año:
2021
Tipo del documento:
Article
País de afiliación:
Canadá