Hydrophilic polymers are known to induce the deposition of sparingly soluble salts. Poly-2-hydroxyethyl methacrylate, (PHEMA), a hydrogel used for the fabrication of contact and intraocular lenses has been reported to favor the nucleation and crystal growth of calcium phosphate. PHEMA disks coated with graphene oxide (GO) were good nucleators of Hydroxyapatite (HAP). which precipitated at rates higher in comparison with the respective on the uncoated material. The mechanism of HAP crystal growth was controlled by surface diffusion as shown by the dependence of the rates on the relative supersaturation with respect to HAP. GO was reduced with phenyl hydrazine at ambient conditions yielding reduced GO (rGO) coated PHEMA. The hydrophobic rGO, inhibited drastically the crystal growth of HAP suggesting that surface hydrophilicity is a very important feature favoring nucleation and growth of sparingly soluble salts, possibly through the development of locally high supersaturation because of surface complexation.
Polymers have played an essential role in development of technology, applied engineering, and materials. Metallic counterparts in medical, construction, energy, water treatment, and electronic applications, are often replaced by polymers. Their characteristics such as wide range of elasticity, strength and degradability make them ideal for numerous applications. Moreover, they have the advantage of low material and processing costs.1 For specific applications, specialized surface treatment of polymers is needed. Surface treatment of polymers is done with plasma and laser treatment, UV radiation, grafting, metallization, ion sputtering etc. The physicochemical properties of the polymers surface are thus modified to fit specific needs and applications. Surface-treated polymers have found widespread use in microfluidics textiles, biomedical applications, electronics, water treatment and energy industries.2,3,4,5,6,7 Chemical surface modification of polymers used quite often. Most chemical surface treatment methods involve wet processes, in which the polymer is dipped or coated or sprayed with a chemical to enhance its surface properties. Surface modification of polymers with graphene attracted considerable research interest 8. Polymeric biomaterials, graphene and graphene oxide are being processed for applications in bone growth scaffolds 9 while protective contact lens coatings have been developed by deposition of graphene films.10 GO is a 2-D material, obtained from oxidation of graphite with strong oxidants.11 GO, in contrast with graphene is hydrophilic, because of the excess oxygen and high surface-to-volume ratio, which allows for its surface modification. The chemical structure of GO makes it attractive for biomedical applications in tissue engineering, drug delivery, wound healing and in medical devices.12 GO, the oxidized form of graphene consists of carbon, oxygen, and hydrogen, constituting possesses carbonyl, carboxyl, hydroxyl, and epoxy groups. GO can be easily dispersed in water forming stable aqueous colloids.13,14 While the surface of GO sheets contains some defects, the general basis of the material bears a strong resemblance to pure graphene.15 The flexibility of GO allows cell growth, while exhibiting antibacterial and antimicrobial properties. High concentrations of GO, however, may cause loss of biocompatibility.16,17 Due to the presence of functional groups, GO may be associated with completely biocompatible and non-toxic polymeric materials.
