Copolymerization of Tri-n-butyltin Acrylate and Tri-n-butyltin Methacrylate Monomers with Vinyl Monomers Containing Functional Groups |
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| Authors: | B. K. Garg J. Corredor R. V. Subramanian |
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| Affiliation: | Department of Materials Science and Engineering , Washington State University , Pullman, Washington , 99164 |
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| Abstract: | A new approach to obtaining thermoset organotin polymers, which permits control of crosslinking site distribution and, through it, a better control of properties of organotin antifouling polymers, is reported. Tri-n-butyltin acrylate and tri-n-butyltin methacrylate monomers were prepared and copolymerized, by the solution polymerization method with the use of free-radical initiators, with several vinyl monomers containing either an epoxy or a hydroxyl functional group. The reactivity ratios were determined for six pairs of monomers by using the analytical YBR method to solve the differential form of the copolymer equation. For copolymerization of tri-n-butyltin acrylate (M1) with glycidyl acrylate (M2), these reactivity ratios were n = 0.295 ± 0.053, r2 = 1.409 ± 0.103; with glycidyl methacrylate (M2) they were r1 = 0.344 ± 0.201, r2 = 4.290 ± 0.273; and with N-methylolacrylamide (M2) they were r1 = 0.977 ± 0.087, r2 = 1.258 ± 0.038. Similarly, for the copolymerization of tri-n-butyltin methacrylate (Mi) with glycidyl aery late (M2) these reactivity ratios were r1 = 1.356 ± 0.157, r2 = 0.367 ± 0.086; with glycidyl methacrylate (M2) they were r1 = 0.754 ± 0.128, r2 = 0.794 ± 0.135; and with N-methylolacrylamide (M2) they were r1 ?4.230 ± 0.658, r2 = 0.381 ± 0.074. Even though the magnitude of error in determination of reactivity ratios was small, it was not found possible to assign consistent Q,e values to either of the organotin monomers for all of its copolymerizations. Therefore, Q,e values were obtained by averaging all Q,e values found for the particular monomer, and these were Q = 0.852, e = 0.197 for the tri-n-butyltin methacrylate monomer; and Q = 0.235, e = 0.401 for the tri-n-butyltin acrylate monomer. Since the reactivity ratios indicate the distribution of the units of a particular monomer in the polymer chain, the measured values are discussed in relation to the selection of a suitable copolymer which, when cross-linked with appropriate crosslinking agents through functional groups, would give thermoset organotin coatings with an optimal balance of mechanical and antifouling properties. |
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