Synthesis, formulation, and characterization of siloxane-polyurethane coatings using combinatorial high-throughput experimentation for underwater marine applications

Biological fouling of marine organisms on ship hulls is an ancient problem. Organo-tin based coatings have been used effectively; however, these coatings harm non-targeted sea-life. Fouling-release coatings appear to be an alternative way to combat fouling. Fouling-release coatings do not necessarily prevent the settlement of marine organisms but permit their easy removal with application of shear to the surface. It has been shown that coatings with low surface energy and low modulus provide easy removal of marine organisms. Poly(dimehylsiloxane)s (PDMS) have low surface energy and low modulus, and have received a lot of attention.; Preliminary studies were carried out to select an appropriate catalyst for synthesis of 3-aminopropyl-terminated PDMS (APT-PDMS) with combinatorial high-throughput experimentation (CHTE). Two combinatorial libraries were designed to synthesize APT-PDMS and PCL-PDMS-PCL, varying the molecular weight of both PDMS and PCL blocks. The two combinatorial synthesis libraries (48 oligomers and block copolymers) were added to siloxane-polyurethane coatings at 4 levels, resulting in 192 siloxane-polyurethane coatings. Coatings prepared from APT-PDMS have higher surface energies than coatings prepared from PCL-PDMS-PCL. On the other hand, coatings prepared from APT-PDMS have lower pseudo-barnacle adhesion than coatings prepared from PCL-PDMS-PCL. From 192 coatings, 16 coatings were down-selected for further analysis with analytical methods and biological workflows.; Novel hydroxyalkyl carbamate-terminated PDMS and dihydroxyalkyl carbamate-terminated PDMS were synthesized by reacting APT-PDMS with ethylene carbonate and glycerine carbonate, respectively. Further reaction of hydroxyalkyl carbamate-terminated PDMS and dihydroxyalkyl carbamate-terminated PDMS with epsilon-caprolactone resulted in carbamate-linked PCL-PDMS-PCL tribock copolymers and H-type PDMS-PCL block copolymers, respectively.; Using CHTE, 72 hydroxyalkyl carbamate-terminated PDMS; dihydoxyalkyl carbamate-terminated PDMS; carbamate-linked PCL-PDMS-PCL triblock copolymers and H-type PDMS-PCL triblock copolymers were synthesized varying the block length of PDMS and PCL. From 72 oligomers, 288 siloxane-polyurethane coatings were formulated by varying the siloxane polymer level in the coatings. The addition of PCL blocks to PDMS increases pseudo-barnacle adhesion for hydroxyalkyl carbamate-terminated PDMS, and the addition of PCL blocks to PDMS backbone decreases pseudo-barnacle adhesion for dihydroxyalkyl carbamate-terminated PDMS.