Synthesis Of Cross-Linked Network Containing Helical Polymers And Their Application In Chiral Recognition

Gels are composed of solvent and three-dimensional networks, and are able to absorb and retain solvent within their network architectures. And the small molecules can be absorbed and released along with the solvent. Helical polymers with ordered secondary structure generally show "chiral amplification" effect, so they often demonstrate extremely high optical activities. The application research of helical polymers along such directions as biomimetic materials, stimuli-response materials, switching materials, chiral catalysis and chiral recognition has made significant progress. So we prepared gels with helical polymers in this study, which present optical activities. Then we examined the enantioselective adsorption performance of the gels. These findings could provide important information for us to further design and develop new materials for applications in chiral recognition and chiral resolution. The main works are as follows:In the present study, we prepared novel gels via one-pot two-step approach. In the first step, optically active helical N-propargylamide copolymer chains, which contained M1 and M2-M5 with Rh catalyst, were synthesized. In the second step, the azo groups in the M1 initiated free radical polymerization of St or MMA in the presence of a crosslinking agent, TMPTA. At last, we successfully synthesized gel 1-gel 11. The gels were characterized by FTIR, SEM, CD and UV spectra, and the swelling ratio. The intense CD effects indicated that the gels synthesized possessed high optical activity. Then we explored the chiral recognition performance of gel 5 as the representative, which showed the preferential adsorption towards to (R)-(+)-phenylethylamine. These results indicate that such gels possess enantioselective recognition ability.N-Propargylamides (M6 and M7) having proline group were synthesized and characterized by FTIR and NMR. Then we prepared the macromonomer poly(7-co-8-co-2) by copolymerization of M7, M2 and M8 simultaneously possessing helical polymer backbones and pendent polymerizable vinyl groups. Poly(7-co-8-co-2) was found to adopt helical structures under the investigated conditions. Next the optically active hydrogel containing proline group was synthesized by the copolymerization of poly(7-co-8-co-2) with N-isopropylacrylamide in the presence of AIBN initiator and BIS cross linker, and the hydrogel was characterized by FTIR, SEM, DSC, CD and UV spectra, and the swelling ratio measurement. The experimental results revealed that the hydrogel synthesized not only exhibited the typical performances that the traditional PNIPAm hydrogels but also presented the expected optical activity.