RESUMO
Superhydrophobic materials rely on both chemical apolarity and surface roughness to achieve the high contact angles and the low roll-off angles that lead to self-cleaning and antibacterial properties. Current superhydrophobic coatings tend to be delicate and lose their properties easily when subjected to droplet impact. Such impact deteriorates these coatings through hydrodynamic wear; changing structure, eroding hydrophobic chemistry, and quickly leading to full wet out of the substrate. In fact, hydrodynamic wear is more detrimental to coatings than seemingly more aggressive mechanical wear including scratching with sandpaper - a common approach used to claim both self-similarity of a material and extreme robustness against wear. What makes certain coatings more robust against hydrodynamic wear? To understand this answer, we systematically study ten disparate self-similar superhydrophobic coating approaches from academia to industry by subjecting them to hydrodynamic wear with rapid droplet impacts. We offer an iteration of a spinning disk methodology that enables parallel testing of multiple coatings simultaneously. We have developed an analytical model that accurately estimates the average size and velocity of droplets created from the spinning disk. We find rapid droplet impacts that simulate a medium rain can deteriorate most coatings within seconds or minutes, with certain exceptions lasting up to 22 days. The more resilient coatings share common attributes including robust apolar chemistry, hierarchal topography, and a slow loss of sacrificial material. The best performing coatings can be characterized using power-law relationships that parallel mechanical fatigue functions and provide a predictive quantitative metric for the performance of hydrophobic coatings. Overall, this paper offers a quantitative approach to hydrodynamic wear of self-similar superhydrophobic coatings.
RESUMO
The biopharmaceutical industry is evolving in response to changing market conditions, including increasing competition and growing pressures to reduce costs. Single-use (SU) technologies and continuous bioprocessing have attracted attention as potential facilitators of cost-optimized manufacturing for monoclonal antibodies. While disposable bioprocessing has been adopted at many scales of manufacturing, continuous bioprocessing has yet to reach the same level of implementation. In this study, the cost of goods of Pall Life Science's integrated, continuous bioprocessing (ICB) platform is modeled, along with that of purification processes in stainless-steel and SU batch formats. All three models include costs associated with downstream processing only. Evaluation of the models across a broad range of clinical and commercial scenarios reveal that the cost savings gained by switching from stainless-steel to SU batch processing are often amplified by continuous operation. The continuous platform exhibits the lowest cost of goods across 78% of all scenarios modeled here, with the SU batch process having the lowest costs in the rest of the cases. The relative savings demonstrated by the continuous process are greatest at the highest feed titers and volumes. These findings indicate that existing and imminent continuous technologies and equipment can become key enablers for more cost effective manufacturing of biopharmaceuticals.
