Study On The Modification Of Microfibre Synthetic Leather Fabrics By Collagen And Its Surface Hydrophilicity

Microfiber Synthetic Leather is a kind of high-grade synthetic leather in which microfiber nonwovens is as substrate to be impregnated with polyurethane,and then they are through a series of surface treatment.The microstructure,appearance quality and performance are most similar to leather.With the enhancement of environmental protection requirements,more environmentally friendly materials,such as waterborne polyurethane are used in the synthesis process of synthetic leather.However,the relatively inert surface properties of microfiber synthetic leather fabrics(MFSLF)are the major drawback which limits its application.Therefore,on the basis of hydroxylated MFSLF(MFSLF-OH),silane coupling agent,imidazole crosslinking agent were used in the hydrophilical modification of MFSLF-OH to prepare the aminated MFSLF(MFSLF-NH2)and thiolated MFSLF(MFSLF-SH).And then MFSLF-NH2 and MFSLF-SH were respectively grafted with different collagen to prepare two kinds of collagen modified MFSLF(MFSLF-NH2-C,MFSLF-SH-CMA).Specific research contents are as follows.Firstly,MFSLF-OH was modified with silane coupling agent(3-aminopropyl)trimethoxysilane(APS)to obtain MFSLF-NH2.The optimal reaction conditions optimized by single factor and orthogonal experiments were that the reaction temperature was 60?,the amount of APS was 0.7 mL and the reaction time was 5 h(based on 2.5 ± 0.2 g of MFSLF-OH).Then MFSLF-NH2 was activated by dipentaerythritol pentaacrylate(5Acl)to prepare double bond-bearing MFSLF(MFSLF-C=C),which lay a foundation for subsequent grafting with collagen.The optimal reaction conditions were that the reaction temperature was 25?,the reaction time was 1.5 h and the amount of 5Acl was 0.5 mL(based on 1.3±0.2 g of MFSLF-NH2).Under these conditions,the grafting rate was 50.5%,the molar ratio of amino groups to double bond was 2:1.And it is speculated that the structure of MFSLF-C=C was two amino groups connecting with a double bond.Finally,collagen was grafted with MFSLF-C=C to obtain the first kind of collagen modified MFSLF(MFSLF-NH2-C).The results showed that the optimal reaction conditions were that the dipping time was 3 h,the dosage of K2S2O8 was 0.054 g and the amount of collagen was 5%(based on 1.3±0.2 g of MFSLF-C=C).Fourier transform infrared spectroscopy(FTIR)and X-ray photoelectron spectroscopy(XPS)was used to characterize the molecular structure of MFSLF-NH2 and MFSLF-C=C.The results showed that the reaction was carried out as expected.The scanning electrons microscopy(SEM)and atomic force microscopy(AFM)analysis showed that the mean square roughness of MFSLF-NH2 and MFSLF-NH2-C were increased by 138.5%and 151.8%,respectively.Compared with MFSLF,the water contact angle of MFSLF-NH2 and MFSLF-NH2-C decreased from 138.7±1° to 87.3 ± 1° and 68.3± 1° respectively,which indicated the surface hydrophilicity,was enhanced.Furthermore,the tensile strength of MFSLF-NH2 and MFSLF-NH2-C were increased by 81.3%and 50.3%,and the elongation at break was changed from 67.23MPa to 73.65 MPa and 55.15 MPa,respectively.N'N-carbonyldiimidazole(CDI)was used to activate MFSLF-OH to prepare CDI activated MFSLF(MFSLF-EIm).The optimal activation conditions obtained by single factor and orthogonal experiments were that the activation temperature was 50?,the CDI dosage was 0.7 g and the activation time was 2 h(based on 2.5 ± 0.2 g of MFSLF-OH).Under the condition the grafting rate was 62.3%.And then MFSLF-SH was prepared by the reaction of MFSLF-EIm with DL-homocysteine thiolactone hydrochloride(DLPA).The optimal reaction conditions were that the amount of DLPA was 0.9 g,the reaction time was 1.5 h,the reaction temperature was 35? and the content of tris(2-aminoethyl)amine(TAEA)was 0.5 mL(based on 1.3±0.2 g of MFSLF-EIm).Under this condition,the content of the thiol group in MFSLF-SH was 0.208 mmol/g.The calculation results showed that an ester imidazoles condensated with fifty DLPA to produce fifty thiol group in situ.Finally,based on the principle of thiol-ene chemical reaction in“click chemistry",the methacrylate modified collagen(CMA)was grafted with MFSLF-SH to obtain the second kind of collagen modified MFSLF(MFSLF-SH-CMA).FTIR and XPS were used to characterize the structure of MFSLF-EIm and MFSLF-SH.The results showed that the reaction was carried out as expected.Compared with MFSLF,SEM and AFM showed the mean square roughness of MFSLF-EIm,MFSLF-SH and MFSLF-SH-CMA were increased by 378.8%,225.2%and 192.3%,respectively.Water contact angle of MFSLF-EIm,MFSLF-SH and MFSLF-SH-CMA decreased from 138.7 ± 1° to 128.3± 1°,97.6 ± 1° and 74.6± 1°,respectively.Furthermore,the tensile strength of MFSLF-EIm,MFSLF-SH and MFSLF-SH-CMA were increased by 29.24%,45.44%and 73.8%.These results showed that the surface hydrophilicity of MFSLF was significantly improved through gradual modification.And the tensile strength of MFSLF-SH-CMA was significantly enhanced after grafting with collagen.The comparison of two kinds of collage modified MFSLF(MFSLF-NH2-C and MFSLF-SH-CMA)showed that MFSLF-SH-CMA was rougher and MFSLF-NH2-C had better hydrophilicity.Compared with MFSLF,the water-vapour transmission rate of MFSLF-NH2-C and MFSLF-SH-CMA were increased by 128.4%and 119.4%.The tensile strength was increased by 50.3%and 73.8%,respectively.In conclusion,MFSLF-NH2-C has better hydrophilicity and moisture permeability,which is more suitable for clothing substrate.MFSLF-SH-CMA has more obvious improvement in mechanical properties,so it can be used as substrate of shoe and sofa leather.