Anionic block copolymerization of cyclotetrasiloxanes initiated by p-bis(dimethyllithiioxysilyl)benzene

✍ Scribed by Zonglin Liu; Yanhui Li; Daqin Wong; Shuxuan Hao

• Publisher: John Wiley and Sons
• Year: 1996
• Tongue: English
• Weight: 469 KB
• Volume: 62
• Category: Article
• ISSN: 0021-8995
• DOI: 10.1002/(sici)1097-4628(19961226)62:13<2355::aid-app21>3.0.co;2-0

✦ Synopsis

The triblock copolymers of poly(dipheny1-b-dimethyl-b-dipheny1)siloxane (PMP) and poly(diphenyl-b-dimethyl-co-methylvinyl-b-diphenyl)siloxane (PMVP) have been synthesized by the dianionic polymerization procedure. The polymerization of the cyclotetrasiloxane monomers initiated by lithium-based initiator has been carried out so as to avoid equilibration reactions. The new initiator, p-bis(dimethyllithiioxysilyl)benzene, was used. Dimethyl formamide (DMF) was used as a promotor. The effects of initiator concentration, polymerization temperature, and polymerization time on the reaction were investigated.

The block copolymers have been determined by 'H-NMR, infrared, ultraviolet, and differential scanning calorimetry. Progressive precipitation separation has been used to study the molecular weight distribution, and the integral distribution curves of the molecular weight have been given.