Study On The Role Of Aldehyde Component In The Chemical Modification Of Silk Fibroin Mannich Reaction

In recent years,as a kind of polymer material,silk fibroin has been paid more and more attention and research outside the field of traditional garments.In recent years,as a kind of polymer material,silk fibroin has been paid more and more attention and research outside the field of traditional garments.Chemical modification method is an effective means to improve the physical and chemical properties of protein.In this paper,we used the Mannich reaction method to modify the aldehyde group The role of the mechanism of protein modification of the theory and technology development has some reference value.The paper first compares the color depth values of silk fibroin fibers modified by Mannich method with formaldehyde,pyruvaldehyde,glutaraldehyde and aromatic primary amine groups.It was found that Mannich method modified silk with synthetic orange D3 when the modification conditions were 2%owf of dye,1:30 of dye:aldehyde(molar ratio),pH of 4,temperature of 30 ?,time of 10 h and liquor ratio of1:50,Formaldehyde modified best,the fabric before and after soaping K/S values were 14.59,9.72,acetone-modified silk fabrics obtained before and after soaping K/S values were 14.61,8.81,glutaraldehyde modified the worst,Before and after the soaping K/S value of only 5.89,1.89.The strength and elongation at break of blanklike,aldehyde-treated and Mannich-modified samples were tested by Tensile Strength Tester.The breaking strength of fabrics treated with aldehyde-treated and Mannichtreated fabrics was improved,which indicated that the aldehyde was not only involved in Mannich reaction,May also have a cross-linking reaction with silk fibroin.Lithium bromide solution dissolution experiment and TG analysis showed that the cross-linking effect of aldehydes increased the stability of modified Mannich method.Secondly,the silk fibers were treated with formaldehyde in the same condition with acidic dyes without aromatic primary amine groups,and the color depth values were compared with Mannich modified silk containing aromatic primary amine dyes.The silk fabric with aromatic primary amine D3 was modified by Mannich method,the K/S value after soaping was 9.30,but the K/S value of acidic dye Orange ?without aromatic primary amine was only 1.97 after soaping,Amine acid dyes and silk bond fastness may be low,may only be ionic bond.In addition,the use of ion-hydrazine mass spectrometry,high performance liquid chromatography and UV-Vis spectroscopy and other means to verify that the aromatic primary amine containing dyes and aldehydes may form Schiff base products,but did not find the reaction between aromatic primary amine containing dyes or Form a cross-linking.Then,the silk fabrics were treated with aldehyde components(formaldehyde,pyruvic aldehyde and glutaraldehyde)under low temperature(temperature 30 ?),and the breaking strength and crease recovery angle were obviously improved compared with those of the original silk samples.The elongation at break did not change much.The structure of silk after aldehyde treatment was characterized by infrared spectroscopy,ion-hydrazine mass spectrometry and thermogravimetric analysis,which showed that the tryptophan,arginine,polypeptide and formaldehyde produced Schiff base Furfural products,which can be further reacted to form crosslinkinged products.TG,lithium bromide solution dissolution experiments showed that the cross-linking reaction increased silk fabric stability.Through the analog reaction of amino acids,aromatic primary amine-containing dyes and aldehydes,it was found that the primary amino-containing dyes and silk amino acid residues formed a covalent cross-linking.In summary,the Schiff base may be formed with the aromatic primary amine based dyes and formaldehyde at low temperature,and then Mannich reaction with the silk fibroin protein.The reaction of tryptophan,arginine and polypeptide with formaldehyde can generate a certain amount of The results showed that the crosslinking of silk fibroin macromolecule segments could be formed.The stability of silk fibroin structure increased and the breaking strength was improved.