Introduction of Disulfide Cross-links into silk

견섬유에 Disulfide기의 도입

Thiol groups were introduced into silk by methoxymethylation using the hemiacetal of formaldehyde and methanol, reaction of the methoxymethyl groups with thiourea to introduce the isothiouronium group and subsequent hydrolysis of the isothiouronium groups. These thiol groups were then oxidized to disulfide groups using hydrogen peroxide. The methoxymethylation of silk was not so feasible as with nylon, and yellowing was observed. The mechanism of the methoxymethylation is discussed. Reaction of methoxymethyl silk with thiourea, hydrolysis of the isothiouronium salt and the oxidation of the thiol groups to disulfide groups are discussed by considering the yields of each reaction. These reactions were also not feasible, but almost half of the introduced methoxymethyl groups could be changed to thiol and disulfide groups.