Effects of chain architectures on the surface structures of conjugated rod-coil block copolymer brushes

Anisotropic electrokinetic transport in channels modified with patterned polymer brushes

Molecular dynamics simulations have been used to predict the transport dynamics of fluids through nanochannels with polymer patterning surfaces. The effects of different parameters, such as separation between polymer stripes, solvent quality, and direction and strength of the electric field, were explored in terms of electroosmotic flow transport characteristics, conformational dynamics of the polymer brush and ion distribution. Anisotropic electrokinetic transport becomes significant due to the surface patterning of polymers when the direction of the electric field is changed. At the separation between adjacent polymer stripes comparable to the chain length, local strong flow close to the bare surfaces weakens dramatically under the electric field along the stripe direction. However, when the electric field is switched to the direction perpendicular to the stripes, the flow is enhanced considerably. The coupling of the polymer solvent quality further richens and complicates the transport behaviors. We explain the physical mechanism of the electroosmotic flow in complex polymer patterning channels by analyzing the interrelationship among various properties.

Functionalization of surfaces with branched polymers

This review summarizes recent developments in the field of surfaces functionalized with branched polymers, including the fabrication methods, morphologies, properties and applications.

Thermoresponsive luminescent electrospun fibers prepared from poly(DMAEMA-co-SA-co-StFl) multifunctional random copolymers

We report novel thermoresponsive electrospun (ES) fibers prepared from multifunctional random copolymers of poly((2-(dimethylamino)ethyl methacrylate)-co-(stearyl acrylate) -co-(9,9-dihexyl-2-(4-vinylpenyl)-9H-fluorene)) (poly(DMAEMA-co-SA-co-StFl)). The moieties of DMAEMA, SA, and StFl were designed to exhibit the thermoresponsive, physical cross-linking, and fluorescent functionality, respectively. The effects of the copolymer compositions on the morphology and photoluminescence of the prepared ES fibers were explored. The prepared P4 copolymer with the DMAEMA/SA/StFl mole ratio of 92/3/5 showed the lower critical solution temperature (LCST) of 32.5 °C. A significant temperature-dependent swelling and de-swelling behavior was found in the P4 ES fibers, which had the diameter of 753 ± 174 nm and 5-10 nm StFl aggregated domain. Accompanied with volume-changing on the P4 ES fibers, a reversible photoluminescence (PL) quenching was also observed during the heating and cooling cycle between 40 and 60 °C. Such reversible switching of the "on-off" PL intensity was probably due to the light absorption ability of the StFl moiety, resulted from the extended/compact structural transformation on the PDMAEMA moiety. Furthermore, the high surface/volume ratio of the ES fibers led a much better temperature response compared with the corresponding spin-coated film. The present study demonstrated that the ES fibers prepared from multifunctional copolymers exhibited the thermoreversible variation on both volume and photoluminescence intensity.