TY - JOUR
T1 - Influence of cross-linker concentration on the cross-linking of PDMS and the network structures formed
AU - Carvalho Esteves, de, A.C.
AU - Brokken-Zijp, J.C.M.
AU - Laven, J.
AU - Huinink, H.P.
AU - Van, M.-P.
AU - With, de, G.
PY - 2009
Y1 - 2009
N2 - The cross-linking of linear di-vinyl-terminated Poly(dimethylsiloxanes) (PDMS) with tetrakis(dimethylsiloxane) was studied in the presence of different concentrations of the cross-linker (H/V = ratio of Si-H groups of the cross-linker and C=C bonds). The consumption of the Si-H and C=C bonds was monitored simultaneously by in situ Confocal Raman Microscopy (CRM) and ATR-FTIR Spectroscopy. When formulations with H/V > 1.0 are cross-linked at low temperature (25 °C) in air and atmospheric humidity conditions, hydrosilylation and secondary reactions occur simultaneously at early stages of the reaction. For H/V = 1.0 the C=C bonds are also consumed by side reactions.Films cross-linked from formulations with different H/V ratios were studied by NMR imaging, swelling/extraction experiments and SEM. Films cross-linked with H/V = 1.0 showed a slower magnetization decay due to the presence of a large percentage of extractable material not connected to the cross-linked network. After extraction, all the films show faster relaxation behavior, explained by the presence of two types of chemical cross-links as well as one type of physical cross-links. These cross-links result from the occurrence of hydrosilylation and secondary reactions and counterbalance each other at different H/V ratios.
AB - The cross-linking of linear di-vinyl-terminated Poly(dimethylsiloxanes) (PDMS) with tetrakis(dimethylsiloxane) was studied in the presence of different concentrations of the cross-linker (H/V = ratio of Si-H groups of the cross-linker and C=C bonds). The consumption of the Si-H and C=C bonds was monitored simultaneously by in situ Confocal Raman Microscopy (CRM) and ATR-FTIR Spectroscopy. When formulations with H/V > 1.0 are cross-linked at low temperature (25 °C) in air and atmospheric humidity conditions, hydrosilylation and secondary reactions occur simultaneously at early stages of the reaction. For H/V = 1.0 the C=C bonds are also consumed by side reactions.Films cross-linked from formulations with different H/V ratios were studied by NMR imaging, swelling/extraction experiments and SEM. Films cross-linked with H/V = 1.0 showed a slower magnetization decay due to the presence of a large percentage of extractable material not connected to the cross-linked network. After extraction, all the films show faster relaxation behavior, explained by the presence of two types of chemical cross-links as well as one type of physical cross-links. These cross-links result from the occurrence of hydrosilylation and secondary reactions and counterbalance each other at different H/V ratios.
U2 - 10.1016/j.polymer.2009.06.022
DO - 10.1016/j.polymer.2009.06.022
M3 - Article
VL - 50
SP - 3955
EP - 3966
JO - Polymer
JF - Polymer
SN - 0032-3861
IS - 16
ER -