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Freeze–thaw poly­(vinyl alcohol) hydrogels (PVA-H) offer great potential for several biomedical applications due to their biomimetic mechanical properties and biocompatibility. Despite these advantages, the use of PVA-H for load bearing applications has been limited due to poor performance in boundary lubrication compared to natural tissue such as articular cartilage. Recently, zwitterionic polymer brushes have been shown to act as effective boundary lubricants on rigid substrates; however, to the best of our knowledge, the synergistic effects of zwitterionic brushes coupled with the biomimetic fluid load support exhibited by hydrogels have not been reported. We report here on our investigation involving the synthesis and characterization of two unique types of polymer brush functionalized PVA hydrogels. The zwitterionic polymers that were compared contained either [2-(methacryloyloxy)­ethyl]­dimethyl-3-sulfopropyl­ammonium hydroxide, PMEDSAH, or 2-methacryloyl­oxyethyl­phosphoryl­choline, PMPC, repeating units. Both hydrogels coated with zwitterionic polymers were found to be cytocompatible. We report further on micrometer-scale surface properties via water contact angle goniometry, surface roughness measurements, and scanning electron microscopy. Finally, the impact of brush functionalization on the mechanics of the tribologically enhanced gels is reported with comparison to natural articular cartilage within the context of Hertzian contact theory.

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Speech is one of the most fundamental forms of self-expression and communication in humans [1]. Voiced speech is produced by fluid-structure interactions that drive vocal fold oscillations, creating a periodic pressure oscillation in the vocal tract. This excitation has a fundamental frequency, typically ranging between 100 and 200 Hz, depending on the individual. Thousands of people lose this ability each year when they are forced to undergo a total laryngectomy, which removes the entire larynx, usually to prevent the spread of cancer. The American Cancer Society predicts there will be about 3,000 laryngectomees in the United States alone during 2013 [2][3].