Solution-cast films of sulfonated block copolymers are investigated for applications in water purification, gas separations, and fuel cells. It is well known that solvent composition influences the structures that form in solutions of sulfonated block copolymers and in the corresponding films. The solutions often contain trace water due to the hygroscopic nature of sulfonated polymers, and the effect of trace water on structure formation has not been previously explored. Water will drive dissociation of sulfonic acid, which in turn might accelerate the rearrangement of polymer chains by disrupting hydrogen bonds between acid groups. In this work, we examine the effects of trace water on the solution-state structure of a sulfonated pentablock copolymer (SPC) and the ultimate film morphology using smallangle X-ray scattering. The solvent used was a mixture of toluene and n-propanol with varying molar ratios of water to sulfonic acid (λ). In solutions with λ = 0, the SPC adopts a disordered structure. The addition of trace water (λ = 3.2) to SPC solutions drives a rapid self-assembly into an ordered lamellar structure. However, the presence of trace water in the solution has little effect on processing the SPC into films as water will rapidly escape from the drying film in a dry environment. For film processing, ambient humidity is more important than trace water in the solution as moisture in air provides a constant supply of water to the film as the solvent evaporates. While there are many variables that control the morphology of solution-cast SPC films, these studies demonstrate that trace amounts of water play a critical role in kinetics and thermodynamics of solution-state self-assembly and the evolution of nanoscale structures during film drying.

The in situ recovery of n-butanol from conventional batch fermentation is an effective strategy to overcome cytotoxic titer limitations. Here, we demonstrate efficient butanol recovery using magnetically responsive micro/mesoporous carbon adsorbents. Although large surface areas (>1400 m2/g) promote adsorption, inclusion of magnetic Ni nanoparticles enables direct and facile magnetic retrieval of spent adsorbents, bypassing the need for column configurations (e.g., packed or expanded bed). Butanol loading capacities of a family of mesoporous powders (4–10 wt %Ni content) are not significantly impacted by Ni content, performing comparably to commercial resins and activated carbons (e.g., up to 0.26 g/g at 12.5 g/L equilibrated butanol). Magnetic recovery of the mesoporous powder is dependent on the Ni content, with up to 89 wt % recovery achieved in 6 min with 10 wt % Ni. Desorption studies using retrieved adsorbents demonstrated an average of 93% recovery of the total adsorbed butanol. Biocompatibility studies using an Escherichia coli model showed no discernible toxicity, even at high Ni content and levels of adsorbent addition. Kinetic studies indicate that neither the effective adsorption or desorption rates should constitute a bottleneck with respect to the future development of a semicontinuous butanol fermentation process using these novel, magnetically responsive adsorbents.