Networks of poly(dimethylsiloxane) (PDMS) are created with electrochemically and optically active iron(II) tris(bipyridine) (Fe(bpy)32+) cross-links which show promise as electrically switchable elastomeric materials or sensors.First, bipyridine-terminated PDMS (bpyPDMS) is synthesized by attaching 4'-methyl-2,2'-bipyridine-4-carboxylic acid to amine-terminated PDMS using a carbodiimide coupling scheme. BpyPDMS is then blended with FeCl2 in differering proportions and the resulting networks are characterized. UV-vis spectra of network films exhibit a strong absorbance peak at ~540 nm indicative of successful Fe(bpy)32+ cross-link formation though attempts to quantify the absorbance are complicated by film thickness and film uniformity. The network is insoluble in several solvents which readily dissolve PDMS. DSC indicates that crystallization is suppressed by the addition of FeCl2 to bpyPDMS, though the network Tg is not significantly different than the Tg of PDMS or bpyPDMS.Network films can be placed on electrode surfaces and swollen with solvent in order to perform cyclic voltammetry (CV). CV studies reveal that the Fe(bpy)32+ cross-links near the electrode are accessible to oxidation, the oxidation is reversible, and the oxidation potential of the cross-links is near that of 'free' Fe(bpy)32+. Spectroelectrochemical measurements indicate that the oxidation of Fe(bpy)32+ is accompanied by a loss of the absorbance peak at 540 nm, and much of the absorbance can be recovered by reducing Fe(bpy)33+ back to Fe(bpy)32+. Figure 1. <img src='https://acs-archive-assets2.s3.amazonaws.com/240nm/uploads/45100_acs-2010.jpg' alt='' />

Poly(dimethylsiloxane) networks with iron(II) tris(bipyridine) crosslinks

247th National Meeting (2014)

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