This article reports on optically active core/shell nanoparticles constituted by chiral helical polymers and prepared by a novel approach: using self-assembled polymer micelles as reactive nanoreactors. Such core/shell nanoparticles were composed of optically active helical-substituted polyacetylene as the core and thermosensitive poly(N-isopropylacrylamide) as the shell. The synthetic procedure is divided into three major steps: (1) synthesis of amphiphilic diblock copolymer bearing polymerizable C[tbond]C bonds via atom transfer radical polymerization, followed by (2) self-assembly of the diblock copolymer to form polymer micelles; and (3) catalytic emulsion polymerization of substituted acetylene monomer conducted using the polymer micelles as reactive nanoreactors leading to the core/shell nanoparticles. The core/shell nanoparticles simultaneously exhibited remarkable optical activity and thermosensitivity. The facile, versatile synthesis methodology opens new approach toward preparing novel multifunctional core/shell nanoparticles.(c) 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012