Spectral characteristics of free and linked pyrene-type chromophores in solution, polymer matrices, and interpenetrating networks

Monomers, 1-pyrenylmethyl methacrylate (PyMMA), 1-pyrenylbutyl methacrylate (PyBMA), 4-(1-pyrenyl)methoxymethyl styrene (PyMMS) and allyl-(1-pyrenylme htyl) ether (PyMAE), with pyrene as chromophore, were prepared. Their spect ral properties (absorption, emission and emission decay) in solution, and d oped or bonded in polymer matrices and complex polymer systems as interpene trating polymer networks (IPN), were investigated. Spectral properties of p yrene-containing monomers doped in polystyrene (PS), polymethyl methacrylat e (PMMA), polyvinylchloride (PVC), polyethylene (PE) and grafted on PE as w ell as copolymerized in buthylmethacrylate-co-styrene copolymer (BMA-co-S) have been compared. Absorption and emission spectra of pyrene type probes i n solution and in IPN matrices exhibit typical absorption of the pyrene moi ety. For IPN with grafted probes on PE, the absorption is slightly shifted to red wavelength. For monomers, PyMMA, PyBMA and PyMAE grafted to PE, the shape of the emission spectrum depends on the wavelength of excitation. The ratio of intensity of the vibrational band, I-1/I-3, (I-1 peak at 377 nm a nd I-3 peak at 388 nm) has been a quite useful indicator of polarity of IPN . The relative quantum yields of fluorescence in IPN matrices are lower in comparison to polymer matrices of PE, PS, PMMA for all probes under study. The fluorescence life-times for bound and free probes have been in the rang e 100-200 ns, which is substiantialy shorter than for the parent pyrene chr omophore under the same or similar condition. Grafted probes on PE alone, o r as a part of IPN, exhibit substantially shorter life-time around 10 ns an d decay is rather complex.