An exploratory study on physical and mechanical properties-transmittance, pendulum hardness, dynamic-mechanical, and tensile-of photopolymerized styrene-butadiene-styrene block copolymer (SBS)-methacrylic monomer systems at different compositions was carried out. The insoluble and crosslinked polymerized systems prepared exhibit a high transmittance along the visible light region and retain the regular structure corresponding to the matrix (SBS), that is, the dynamic-mechanical spectra show the two peaks corresponding to the PS and PB phases in the tan delta-temperature plot. Trapped radicals remain in the photopoymerized SBS-methacrylic monomer (tetra or hexafunctional) system, so when these systems are heated above their vitreous transition temperature, a postpolymerization reaction is produced that gives rise to an increase of both the crosslinking density and the storage modulus. The modulus and ultimate tensile strength of the polymerized SBS-hexanediol dimethacrylate (HDDMA) systems increase with increasing initial proportions of the dimethacrylate monomer; on the contrary, the percent elongation at break and toughness decrease with increasing proportions of initial dimethacrylate monomer. (C) 2003 Wiley Periodicals, Inc.