Cyclic poly(dimethylsiloxane) via ring-closing dehydrocoupling of α,ω-dihydroxy-PDMS with α,ω-dihydrido-PDMS in dilute solution
✍ Scribed by Marcus Foston; Haskell W. Beckham
- Book ID
- 104088266
- Publisher
- Elsevier Science
- Year
- 2010
- Tongue
- English
- Weight
- 434 KB
- Volume
- 51
- Category
- Article
- ISSN
- 0032-3861
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✦ Synopsis
Cyclic poly(dimethylsiloxane) (PDMS) was prepared from commercially available linear a,u-dihydroxy-PDMS by a platinum-catalyzed dehydrocoupling of its chain ends with a,u-dihydrido-PDMS in dilute solution. Ring closing was verified by MALDI-ToF mass spectrometry along with GPC, IR, 1 H and 29 Si NMR spectroscopy. Purification of the cyclic PDMS was achieved by inclusion complexation of linear byproducts with g-cyclodextrin. Cyclic yields are ! 50% and the average molecular weight (M) closely reflects that of the linear starting material. Yields of large cycles, [(CH 3 ) 2 SiO] x where x > 6, are greater than those achieved by the traditional ring-chain equilibration route beginning with [(CH 3 ) 2 SiO] 4 and [(CH 3 ) 2 SiO] 5 [1], and the M is greater than that obtained for the cyclic product obtained from basecatalyzed cyclodepolymerization of the same a,u-dihydroxy-PDMS precursor [2].