Sol-gel preparation and photophysical properties of pseudo-interpenetrating polymer networks based on poly(3-alkylthiophene)/polysiloxane glass

In this work poly(3-hexadecylthiophene) (P3HDT) was dispersed in a polysilo xane polymer network and in a hybrid organic inorganic copolymer network po lysiloxane/(3-mercaptopropyl)trimethoxysilane (3MPTMOS) using the sol-gel p rocess. Spectroscopic analysis in the ultraviolet-visible region as a funct ion of temperature shows that the tetraethoxysilane/poly(3-hexadecylthiophe ne) (TEOS/P3HDT) pseudo-interpenetrating polymer network (pseudo-IPN) has e mission band centered at 5400 +/- 75 Angstrom at 25 degrees C which we attr ibute to P3HDT. At 100 degrees C this emission band intensity decreases by almost half and has blue shift to 5000 +/- 100 A. As the temperature is fur ther increased an increase in the intensity of this 5000 +/- 100 A band is observed. On the other hand the TEOS-3MPTMOs/P3HDT pseudo-IPN has an emissi on maximum at 5000 +/- 100 A at 25 degrees C and instead of a blue shift an unusual red shift to 5800 +/- 100 A is observed as the temperature increas es. Using sol-gel processing techniques we have prepared a new type of lumi nescent glass composite with luminescence properties covering a region of t he visible spectrum from 4000 to 7000 Angstrom. The control of the electron ic and optical properties we explain by the interaction and geometric restr iction imposed by the inorganic host matrix together with the thermochromic properties of P3HDT. (C) 2000 Elsevier Science B.V. All lights reserved.