Safer carbon nanotube processing expands industrial and consumer applications.

Safer, less-reactive superacid processing enables printing and coating of carbon nanotubes into films, fibers, and fabrics.

Effect of fiber diameter, pore size and seeding method on growth of human dermal fibroblasts in electrospun poly(epsilon-caprolactone) fibrous mats.

Nonwoven fiber mats of poly(epsilon-caprolactone) (PCL) and PCL blended with poly(ethylene oxide) (PEO) were generated by electrospinning. Differential scanning calorimetry, scanning electron microscopy, and gravimetric measurement confirm the removal of PEO after immersion in water, as well as an increase in the PCL crystallinity. The reorganization of PCL resulted in the macroscopic alteration of the electrospun mat, decreasing the peak pore diameter up to a factor of 3 while only minimally affecting the fiber diameter. This technique was used to create electrospun PCL scaffolds with similar fiber diameters but different pore diameters to examine the effect of pore diameter on cell growth. Human Dermal Fibroblasts (HDF) were seeded into multiple samples using a perfusion seeding technique to guarantee successful cell deposition. Fluorescence analysis at 7, 14, and 21 days found that cells proliferated at a faster rate on scaffolds with peak pore diameters greater than 6 microm, as determined by mercury porosimetry. Cell conformation was also found to change as the peak pore diameter grew from 12 to 23 microm; cells began aligning along single fibers instead of attaching to multiple fibers. Knowledge of the effect of void architecture on cell proliferation and conformation could lead to the development of more effective scaffolds for tissue engineering.

Spraying asymmetry into functional membranes layer-by-layer.

As engineers strive to mimic the form and function of naturally occurring materials with synthetic alternatives, the challenges and costs of processing often limit creative innovation. Here we describe a powerful yet economical technique for developing multiple coatings of different morphologies and functions within a single textile membrane, enabling scientists to engineer the properties of a material from the nanoscopic level in commercially viable quantities. By simply varying the flow rate of charged species passing through an electrospun material during spray-assisted layer-by-layer deposition, individual fibres within the matrix can be conformally functionalized for ultrahigh-surface-area catalysis, or bridged to form a networked sublayer with complimentary properties. Exemplified here by the creation of selectively reactive gas purification membranes, the myriad applications of this technology also include self-cleaning fabrics, water purification and protein functionalization of scaffolds for tissue engineering.

Electrospun poly(styrene-block-dimethylsiloxane) block copolymer fibers exhibiting superhydrophobicity.

Block copolymer poly(styrene-b-dimethylsiloxane) fibers with submicrometer diameters in the range 150-400 nm were produced by electrospinning from solution in tetrahydrofuran and dimethylformamide. Contact angle measurements indicate that the nonwoven fibrous mats are superhydrophobic, with a contact angle of 163 degrees and contact angle hysteresis of 15 degrees . The superhydrophobicity is attributed to the combined effects of surface enrichment in siloxane as revealed by X-ray photoelectron spectroscopy and surface roughness of the electrospun mat itself. Additionally, the fibers are shown by transmission electron microscopy to exhibit microphase-separated internal structures. Calorimetric studies confirm the strong segregation between the polystyrene and poly(dimethylsiloxane) blocks.