As part of ongoing efforts aimed at the development of extensive structure−property relationships for moisture-curable polysiloxane coatings containing tethered quaternary ammonium salt (QAS) moieties for potential application as environmental friendly coatings to combat marine biofouling, a combinatorial/high-throughput (C/HT) study was conducted that was focused on four different compositional variables. The coatings that were investigated were derived from solution blends of a silanol-terminated polydimethylsiloxane (HO-PDMS-OH), QAS-functional alkoxysilane, and methyltriacetoxysilane. The compositional variables investigated were alkoxysilane functionality of the QAS-functional silane, chain length of the monovalent alkyl group attached to the QAS nitrogen atom, concentration of the QAS-functional alkoxysilane, and molecular weight of the HO-PDMS-OH. Of these variables, the composition of the alkoxysilane functionality of the QAS-functional silane was a unique variable that had not been previously investigated. The antifouling (AF) and fouling-release (FR) characteristics of the 24 unique coating compositions were characterized using HT assays based on three different marine microorganisms, namely, the two bacteria, Cellulophaga lytica and Halomonas pacifica, and the diatom, Navicula incerta. Coatings surfaces were characterized by surface energy, water contact angle hysteresis, and atomic force microscopy (AFM). A wide variety of responses were obtained over the compositional space investigated. ANOVA analysis showed that the compositional variables and their interactions significantly influenced AF/FR behaviors toward individual marine microorganisms. It was also found that utilization of the ethoxysilane-functional QASs provided enhanced AF character compared to coatings based on methoxysilane-functional analogues. This was attributed to enhanced surface segregation of QAS groups at the coating-air interface and confirmed by phase images using AFM.
A high-throughput workflow was developed for the study of porous polymers generated using the process of chemically induced phase separation. The workflow includes automated, parallel preparation of liquid blends containing reactive, polymer network-forming precursors and a poragen, as well as a high-throughput poragen extraction process using supercritical CO 2 . A structure-process-property relationship study was conducted using epoxy-amine cross-linked networks. The experimental design involved variations in polymer network cross-link density, poragen composition, poragen level, and cure temperature. A total of 216 unique compositions were prepared. Changes in opacity of the blends as they cured were monitored visually. Morphology was characterized using a scanning electron microscope on a subset of the 216 samples. The results obtained allowed for the identification of compositional variables and process variables that enabled the production of porous networks.
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