ABSTRACT:Two photocrosslinkable NLO polymers of poly(glycidyl methacrylate) substituted with 4-nitro-4Ј-hydroxyl stilbene (PGMAS) and acryloyl-functionalized epoxybased polymer (PENAA) carrying 4-nitroaniline moieties were synthesized and characterized. By using the sulfonium salt cationic photoinitiator BDS ⅐ 2PF 6 which can induce cationic or/and radical polymerization, the photocrosslinking of PGMAS and the interpenetrating polymer network (IPN) formed by the photocrosslinking of PGMAS and PENAA simultaneously were reported. The poled and photocrosslinked polymer films and IPN films exhibit relatively stable second-order nonlinear optical activity. The influence of stilbene isomerization in PGMAS films with different crosslink densities on the SHG stability was also investigated.

Two interpenetrating polymer networks (IPNs), (one pseudo‐IPN consisting of a linear polyurethane/epoxy‐based polymer network and one full‐IPN consisting of a poly(methyl methacrylate)/epoxy‐based polymer network) have been synthesized and characterized. Both IPNs showed only one Tg; hence a homogeneous phase morphology is suggested. The second‐order non‐linear optical coefficients (d33) of the pseudo‐IPN and the full‐IPN were measured and found to be 2.78 × 10−7 esu and 1.86 × 107 esu, respectively. The study of temporal stability at room temperature and elevated temperature (120 °C) indicates that the full‐IPN is more efficient at improving the orientational stability of the non‐linear optical chromophores than the pseudo‐IPN, because of the permanent entanglements of the two component networks in the full‐IPN. © 1999 Society of Chemical Industry