Poly(dipentylsilylene) copolymers containing n-pentyl-n-oct-7-enylsilane units were prepared by reductive coupling of the corresponding dichlorosilanes. Linear high molecular weight and some crosslinked polymer were obtained. The soluble products exhibited optical and thermal properties like poly(dipentylsilylene). Differential scanning calorimetry was used to investigate crystallization and to monitor thermal crosslinking. Vinyl functionalized side chains were hydrosilylated with dipentylsilane and dimethylchlorosilane and crosslinked via the side chains. Hydrosilylation with di-n-pentyl(trimethylsiloxypropyl)silane led to a partial hydroxy functionalization of the polysilylene and enabled anionic PEO grafting of the poly(dipentylsilylene).