High Efficiency Platinum Acetylide Nonlinear Absorption
Chromophores Covalently Linked to Poly(methyl methacrylate)
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Abstract
We
report three platinum acetylide acrylate monomers containing known
two-photon absorption (TPA) chromophores and their covalent incorporation
into polymers via free radical polymerization with methyl methacrylate.
The photophysical properties of the platinum acetylide monomers and
resulting poly(methyl methacrylate) (PMMA) copolymers were investigated
to determine if the one- and two-photon photophysical properties of
the chromophores were maintained in the copolymers. The photophysical
properties of the series of copolymers were studied in solution and
solid state with minimum shifts exhibited in the ground state absorption,
photoluminescence, and triplet–triplet transient absorption
spectra. The polymer films displayed markedly stronger phosphorescence
and longer triplet excited state lifetimes than the polymers in solution
or the monomers. The incorporation of the platinum acetylide chromophores
into the PMMA copolymers allows the materials to be cast as thin films
or into free-standing monoliths. Films with ∼3.6 μm in
thickness and monoliths with 1 mm path length were fabricated and
examined. The nonlinear absorption responses of the polymers in solution
were measured via the nanosecond <i>z</i>-scan method, and
the solid state polymer monoliths were measured via nonlinear transmittance.
Both measurements indicate that the polymers exhibited strong transmittance
attenuation at input pulse energies exceeding 100 μJ