Synthesis of hyperbranched polycarbosilanes by hydrosilylation of triallylsilane is reported. Soluble high molecular weight polymer was obtained in an uncontrolled bulk reaction. Addition of 2-( 10-decen-1-y1)-13-oxazoline (i) afforded control over degree of polymerization (DP) and (ii) resulted in hyperbranched macromonomers. 17000 1 aw 1 800 (GPC (PS)) was obtained. 29Si NMR spectroscopy allowed identification of dendritic, branched, linear, and terminal silicon branch-points. A modified definition for the degree of branching yielded a value of 0.48 * 0.05 (theory: 0.44).

Chemical reactions during polymer melt processing afford a wide range of highly diversified polymers derived from well‐known polymers. This technology, especially functionalization, grafting, in‐situ formation of copolymers, segmented polymers, and compatibilizers, plays a key role in the development of novel thermoplastics including blends, composites, and polymers from renewable resources. Oxazolines are useful highly reactive and selective intermediates for polymer melt modification.