Robust and hydrophilic polymeric films with honeycomb pattern and their cell scaffold applications

Starting from a commercially available block copolymer, polystyrene-b-polybutadiene-b-polystyrene (SBS), micro-patterned polymer films were successfully prepared by evaporating SBS/carbon disulfide solutions with different concentrations under high humidity. The influence of solution concentration on the pore size and array was investigated in detail. With the increase of solution concentration, regular pore arrays turned into random because of weakened convention. Once the concentration was more than 60 mg mL(-1), a bimodal size distribution appeared. Photo-chemical cross-linking was achieved by exposing the polymer films in deep UV light (wavelength 254 nm), monitored by attenuated total reflective Fourier transform infrared and X-ray photoelectron spectroscopy. After 1 h cross-linking, either solvent resistance or thermal stability or surface wettability of the films was significantly improved. The cross-linked honeycomb structured films became resistant to a wide range of organic solvents and thermally stable up to 350 degrees C, an increase of more than 250 K as compared to the un-crosslinked films. Another beneficial effect of the photo-chemical process was the formation of polar groups on the film surface, changing surface wettability from hydrophobicity to hydrophilicity, enhanced by the micro-patterned surface. The resultant films were non-cytotoxic and hence suitable as cell scaffolds. It was found that hydrophilic, micro-patterned polymer films with a uniform pore size of 3 mm facilitated cell attachment and proliferation.