Y. Israeli et al., PHOTOOXIDATION OF POLYDIMETHYLSILOXANE OILS .3. EFFECT OF DIMETHYLENEGROUPS, Polymer degradation and stability, 42(3), 1993, pp. 267-279
Photo-oxidations at wavelengths longer than 300 nm of polydimethylsilo
xanes (PDMS) formed by hydrosilylation reactions (i.e. containing dime
thylene (approximately CH2-CH2 approximately) and methine [GRAPHICS] g
roups) have been examined. The consumption of initial functional group
s and the appearance of new groups derived from the photo-oxidation we
re followed by FTIR. H-1, C-13 and Si-29 NMR and GC/MS. The main photo
-oxidation process is the hydroperoxidation of dimethylene groups and
the photoscission of hydroperoxide groups into beta-silylated carboxyl
ic acid (approximately SiCH2-COOH) and silanol groups (SiOH). A small
part of the silanols formed is condensed into ester and siloxane group
s.