| 초록 |
A strained ring, such as an epoxy, is a system ready to open and release the strain with a suitable nucleophile. For example, a thiol molecule can be deprotonated by a base and the resulting thiolate anion can attack the less hindered site of the epoxide unit. The alkoxide unit formed will be protonated due to its high basicity(pKa~17) by the thiol group(pKa~10). This thermodynamically driven proton transfer step is critical in quenching the alkoxide anion and its potential to start an anionic ring opening polymerization. The newly formed thiolate anion would be ready for attacking another epoxide ring, creating a second alkoxide anion. Repetition of the above steps would result a polymeric product. Our goal in this presentation would be to demonstrate that a photochemical stimulus can be applied to initiate a proton transfer polymerization process, and fabrication of nano, micrometer-sized hydrogel features prepared by micromolding in capillary and imprint lithography strategies. |
