Journal of Biomaterials Science 22 (2011) 139–152 brill.nl/jbs Synthesis and Characterization of Co-polymers Based on Methyl Methacrylate and 2-Hexyl Acrylate Containing Naphthopyrans for a Light-Sensitive Contact Lens Cláudia R. J. O. D. Nabais a , B. Mark Heron b , Hermínio C. de Sousa c , Maria H. Gil c and Abílio J. F. N. Sobral d,∗ a Departamento de Engenharia Mecânica e Gestão Industrial, Faculdade de Engenharia da Universidade do Porto, 4200-465 Porto, Portugal b Department of Colour and Polymer Chemistry, University of Leeds, Leeds LS2 9JT, UK c CIEPQPF, Chemical Engineering Department, University of Coimbra, Pólo II–Pinhal de Marrocos, Rua Sílvio Lima, 3030-790 Coimbra, Portugal d Departamento de Química, Faculdade de Ciências e Tecnologia da Universidade de Coimbra, 3004-535 Coimbra, Portugal Received 3 March 2009; accepted 12 November 2009 Abstract Three different naphthopyrans were incorporated in co-polymers of methyl methacrylate (MMA) and 2- ethylhexyl acrylate (EHA), with and without cross-linking with ethyleneglycol dimethacrylate (EGDMA), by a free radical polymerization method. The obtained materials were characterised in terms of some of their chemical and physical properties that could be important for the final functional properties of the envisaged application. Despite other important functional properties that should be evaluated in the near future, the system based in the physical entrapment of 3,3-bis(4-methoxyphenyl)-3H-naphtho [2,1-b]pyran presented a good potential for its application as novel light-sensitive contact lenses.  Koninklijke Brill NV, Leiden, 2011 Keywords Methyl methacrylate, 2-ethylhexyl acrylate, naphthopyrans, photochromic contact lenses 1. Introduction The application of polymeric materials in ophthalmology has been the subject of a large number of publications in recent years [1–3]. Real and potential uses include, for example, the preparation of contact lenses, intraocular lenses ophthalmic inserts and artificial cornea [4–7]. The particular case of contact lenses provides not only a safe and efficient way of correcting some problems with vision (e.g., myopia, * To whom correspondence should be addressed. E-mail: asobral@ci.uc.pt  Koninklijke Brill NV, Leiden, 2011 DOI:10.1163/092050609X12580984253769