Photonic band gap materials attracted a great deal of attention as potential candidates for various optoelectronic applications.1 Within this field, elastomeric polymer-based colloidal crystals, also referred to as synthetic opal films, show a reversible mechanochromic response while stretching with excellent color changes.2,3 The lack of mechanical strength in such opal films, which is a basic prerequisite for a reversible combined optical and mechanical response, can be overcome by subsequent photo- or thermally induced cross-linking reactions.3,4 However, cross-linking processes are necessary which reliably do not proceed under the conditions of colloidal crystallization and compression molding but which can be activated a posteriori. Within this contribution an in-situ cross-linked network, generated by subsequent UV irradiation of the melt-flow opal films as well as a thermally induced cross-linking protocol is described. Efficient reactions for thermally induced cross-linking are based on the chemistry of epoxides, alcohols and isocyanates. Monomers bearing the corresponding epoxide and alcohol functionalities were introduced into the seeded emulsion polymerization in order to obtain monodisperse particles with diameters in the range of 100-500 nm. As a result, the combined mechanical and optical properties of the opal films can be significantly improved. Studying the mechanical properties of these novel elastomeric opal films together with investigations of the excellent optical properties revealed that original iridescent reflection colors can be achieved after stretch-tuning and relaxation.1. J.F. Galisteo-L�pez, C. L�pez et al., Adv. Mater. 2011, 23, 30.2. C.G. Sch�fer, M. Gallei et al., Chem. Mater. 2013  , 25, 2309.3. C.G. Sch�fer, M. Gallei et al., Langmuir 2013  , 29, 11275.4. C.G. Sch�fer, M. Gallei et al., ACS Appl. Mater. Inter. 2013,   5, 10623.

Efficient cross-linking strategies in colloidal crystal films featuring enhanced photonic and mechanical properties

248th National Meeting (2014)

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