Cross-Linking and Degradation Properties of Plasma Enhanced Chemical Vapor Deposited Poly(2-hydroxyethyl methacrylate) Courtney A. Pfluger, Rebecca L. Carrier, Bing Sun, Katherine S. Ziemer, Daniel D. Burkey * Introduction Poly(2-hydroxyethyl methacrylate) (PHEMA) is one of the major synthetic polymers approved by the FDA for biomedical and pharmaceutical applications, [1] as it is nontoxic, biocompatible, and possesses adequate mechan- ical strength for most biomedical applications. [2–4] There are numerous examples of PHEMA’s use in cell culture applications. Mabilleau et al. successfully demonstrated that J774.2 macrophage cells cultured on a PHEMA surface both proliferated and maintained a high viability. [5] Also, Merrett et al. cultured corneal epithelial cells on PHEMA with similar positive results. [6] Biodegradable polymers such as PHEMA are found to be useful as drug delivery vehicles because of their ability to break down in a controllable fashion and degrade into naturally occurring or inert chemicals in the body. [7] PHEMA, due to its hydrophilic nature, hydrates when exposed to water, becoming a hydrogel. Over time, the polymer is hydrolyzed resulting in erosion of the matrix. [8] These PHEMA hydrogels have been shown to be useful for cell immobilization, [9–11] coating drug delivery devices for neural micro-electrode arrays, [12] artificial skin, [13] corneal replacements and repairs, [6,14] controlled drug release, [15] and as synthetic articular cartilage. [16,17] Understanding the degradation of PHEMA films is important because both porosity and hydrogel formation depend on how the film degrades over time. Chemically Communication C. A. Pfluger, R. L. Carrier, B. Sun, K. S. Ziemer, D. D. Burkey Department of Chemical Engineering, Northeastern University, Boston, Massachusetts 02115, USA E-mail: pfluger.c@neu.edu; r.carrier@neu.edu; sun.b@neu.edu; kziemer@coe.neu.edu; d.burkey@neu.edu Plasma Enhanced Chemical Vapor Deposition (PECVD) of poly-2-hydroxyethyl methacrylate (pHEMA) biocompatible, biodegradable polymer films were produced alone and cross-linked with ethylene glycol diacrylate (EGDA). Degree of cross-linking was controlled via manipula- tion of the EGDA flow rate, which influenced the amount of swelling and the extent of degradation of the films in an aqueous solution over time. Noncross-linked pHEMA films swelled 10% more than cross-linked films after 24 h of incubation in an aqueous environment. Increasing degree of film cross-linking decreased degradation over time. Thus, PECVD pHEMA films with variable cross-linking properties enable tuning of gel for- mation and degradation properties, making these films useful in a variety of biologically significant applications. 126 Macromol. Rapid Commun. 2009, 30, 126–132 ß 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim DOI: 10.1002/marc.200800647