| In the field of marine navigation, drag reduction and anti-biofouling is so long a subject. It is a relatively easy way to overcome the drag and biofouling by coatings. In this work, coating with thermo-sensitive and salt-sensitive properties is prepared, and a new thought to overcome the drag and biofouling may appear. Specific works are as follows:1. Using N-isopropylacrylamide (NIPAM) as the basic monomer, PEGMA as macromolecular stabilizer agent, BIS as crosslinker, dual sensitive (thermo-sensitive and salt-sensitive) microgel is prepared. GMA is added during the process for the purpose of crosslinking when preparing the coating. Results showed that dual sensitive microgel with micrometer size and nanometer size can be prepared with NIPAM, PEGMA, GMA, BIS, AIBA and the particle size of the microgel decreases as the content of PEGMA increases, and dual sensitive properties tend to be weak as the content of PEGMA increases.2. Acrylate polymer emulsion with uniform particle size is prepared as base material of coating through emulsifier-free emulsion polymerization. GMA is added in the process for the purpose of crosslinking when preparing the coating too. Tg is adjusted by the mass ratio of MMA and BA. Results showed that when the mass ratio of MMA, BA and GMA is 25:15:1, solid content is 5%, the initiator (AIBA) is 13wt% relative to all the monitors, polymerization temperature is 70?, polymerization time is 24h, conversion rate can be up to 98.2%, the particle size is 290.7nm.3. The microgel and the latex are blended at 80? with crosslinking agent to prepare the crosslinked coating. The optimum molecular weight and the optimum content of PEI are studied. Three kinds of PEI with different molicules of 1000,2000 and 5000 are studied. Result showed that epoxy groups react with amine groups and crosslinked coating is obtained. The optimum molecular weight and the optimum mol ratio of amine groups are 2000 and 0.6 to epoxy groups and the gel content is up to 99%.4. The relationship of the drag-reducing efficiency of the coating with the composition of the coating and the environment is studied by torque testing, including the content of microgel, the content of PEGMA unit in the microgel, the particle size, different temperatures and concentrations of NaCl. Results showed that drag-reducing efficiency increases as the content of microgel and the content of PEGMA units in the microgel increase, but when the content of microgel is more than 8wt%, drag-reducing efficiency begins to decrease, and the best drag-reducing efficiency is almost 50% compared to coatings without microgel (15?). Drag-reducing efficiency decreases as temperature and concentration of NaCl increase, and a jump point appears at the LCST of the microgel. The coating appears sensitivities to temperature and concentration of NaCl because of dual sensitivity of the microgel combining the result of DLS.5. The relationship of the anti-biofouling efficiency of the coating to BSA-FITC with the composition of the coating and the environment is studied, including the content of microgel, the content of PEGMA unit in the microgel, the particle size, different temperatures and concentrations of NaCl. Result showed that anti-biofouling efficiency increases as the content of microgel and the content of PEGMA units in the microgel increase. Compared to the coating without microgel, the anti-biofouling efficiency is 90% when the mass content of the microgel is 12%(15?). When mass content of microgel is 9%, and the temperatures are 15?, 37? and alternative temperatures, anti-biofouling efficiency increases and the best is 90%. Dynamic characteristics of coating facilitate anti-biofouling.6. Coatings with drag-reducing and anti-biofouling efficiency are at the same time obtained. |
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