Structural studies of asymmetrically substituted poly(di-n-alkylsilanes) as a function of pressure have shown that side-chain architecture is important for the observation of piezochromism. UV-vis, Raman, and FTIR measurements of poly(di-n-alkylsilanes) with linear side chains of two different lengths indicate that a piezochromic shift of the UV-vis absorption maximum at 315 nm is observed. However, if instead one or both of the side chains are branched, the Si backbone is prevented from adopting a planar zigzag conformation and hence no large changes in the UV-vis spectrum are observed. © 1992, American Chemical Society. All rights reserved.