Synthesis And Tanning Properties Of Cage-containing Sesquisiloxane Polymers

With the increasingly severe environmental problems and the strategic consideration of chromium resources,it is imperative to develop novel environmentally friendly non-chromium tanning agents.Cage silsesquioxane(POSS)has a unique intramolecular organic-inorganic hybrid structure.The inorganic core provides good structural stability and thermal stability.The peripheral organic groups can be designed according to requirements to make it suitable for various fields.Our group have studied the application of polycarboxyl POSS/polymer hybrid materials and octa amino POSS in the field of leather tanning.On this basis,this topic aims to prepare a POSS polymer containing both amino and carboxyl groups and POSS was introduced into biomass polysaccharides to prepare POSS grafted oxidized sodium alginate polymer material,and its tanning performance was studied.The specific research content is as follows:Vinyl cage type sesquisiloxane(POSS-Vi),acrylamide(AM)and methacrylic acid(MAA)were used as raw materials to prepare POSS polymer containing amino and carboxyl(P(POSS-AM-MAA))by free radical polymerization.Fourier infrared spectroscopy(FT-IR),X-ray diffractometer(XRD),transmission electron microscope(TEM)were used to characterize the structure and morphology of P(POSS-AM-MAA).The results showed that the composite P(POSS-AM-MAA)had a cubic cage structure of POSS surrounded by polymer segments.The P(POSS-AM-MAA)combined with 4%glutaraldehyde were used in the tanning process of goat pickled skin.The ratio of AM and MAA monomer,the amount of initiator,and the amount of P(POSS-AM-MAA)were investigated.The results showed that:when the ratio of AM to MAA in the composite P(POSS-AM-MAA)was 4:1,the amount of initiator was 4%,the P(POSS-AM-MAA)dosage was 8%and the combined pH was 8.5.The shrinkage temperature of the leather reached 83.7? and the thickening rate was 107.3%,which was higher than that of the glutaraldehyde tanned crust leather alone.The tensile strength,elongation at break and the tear strength of combined tanned leather was 16.5 MPa,109.5%,and 58.8 N/mm,which was equivalent to the glutaraldehyde tanned leather.Using sodium alginate(SAG),MAA and POSS-Vi as raw materials,the POSS grafted sodium alginate polymer(POSS-SAG-MAA)was prepared by graft polymerization,and further oxidized by sodium periodate,and obtained the POSS grafted oxidized sodium alginate polymer material(POSS-OSA-MAA).The structure and thermal stability of POSS-OSA-MAA were characterized by FT-IR,XRD,nuclear magnetic resonance spectrometer(NMR)and thermogravimetric analysis(TG).The results showed that:POSS-OSA-MAA was successfully synthesized,and the thermal stability of POSS-OSA-MAA was significantly higher than that of SAG.Employing POSS-OSA-MAA in leather tanning process,the effect of oxidation time and oxidant ratio on the tanning performance were studied.The tanning results showed that when the oxidation time was 20 h and the ratio of oxidant to POSS-SAG-MAA was 0.4:1,it exhibited the best the tanning effect.Compared with using only OSA alone,the shrinkage temperature increased from 68.9? to 73.1? and the thickening rate increased from 24.3%to 42.9%,the POSS-OSA-MAA tanned leather had higher mechanical properties..POSS-OSA-MAA was combined with skin collagen mimics,gelatin and collegn fibers under tanning conditions,and the products were characterized by XPS,FT-IR,XRD,UV,TG,fluorescence spectroscopy and other methods.The results showed that:POSS-OSA-MAA was combined with the amide group and hydroxyl group of the collagen by hydrogen bonding,and could form covalent bond with the amino group.POSS-OSA-MAA modified gelatin had higher thermal stability than OSA modified gelatin,because POSS-OSA-MAA could form more covalent bonds with gelatin.The POSS-OSA-MAA tanned leather had higher thermal stability and more dispersion than the OSA tanned leather.