Novel optically-active methacrylic homopolymers bearing in the side chain one or more chiral groups of one single configuration (based on the L.-lactic acid residue) linked to the spiropyran chromophore, have been successfully synthesized and fully characterized. These intrinsically chiral polymers exhibit remarkable thermal stability, with glass transition temperatures in the range 100-130 degrees C and decomposition temperatures around 270 degrees C. The chiroptical characterization indicates the occurrence of asymmetric induction on the electronic transitions of the side-chain chromophore related to the number of L-lactic acid residues interposed between the main chain and the spiropyran chromophore. In the presence of acid, these systems can be used to modulate the protonation of polymeric azopyridine moieties upon photoisomerization of the spiropyran group. In addition to UV-Vis spectroscopy, the proton transfer process occurring between the macromolecular components can be also followed by CD spectroscopy, the system thus behaving as a chiroptical switch. (C) 2012 Elsevier Ltd. All rights reserved.