Study On Preparation And Properties Of Copolymers Of Starch, Phenols And Vinyl Monomer With HRP Catalysis

Enzyme catalysis has the characteristics of high efficiency, strong selectivity, mild reaction conditions, green environmental and so on. Products, which are difficult to synthesize by means of traditional chemical method, can be obtained by enzyme catalysis, so enzyme catalysis is widely used in various fields such as food industry, light industry, medicine, perfume, environmental protection and energy. In this paper, free radical graft copolymerisation of starch and vinyl monomer and the copolymerization of phenols and aromatic amines monomers were carried out using horseradish peroxidase (HRP) as catalyst. The products were used as leather retanning agent, and the application effect was studied.Firstly, the preparation and application of modified starch retanning agent was researched. It was explored that the new graft copolymerization reaction system of starch and acrylamide (AAM) by means of HRP/H2O2/acetylacetone (ACAC), and starch-polyacrylamide graft copolymer was synthesized. The main factors that affect the polymerization were discussed and the optimum reaction conditions were determined as follows:50 g distilled water and 5 g starch were put into a 500 mL three-neck round-bottom flask to gelatinization in high temperature for 10 min, then cooling to ambient temperature. Appropriate amount phosphate buffer solution was put into the flask to control the system pH 7.0, then 3 g AAM and 0.2 g ACAC were added to the flask together, and catalyst was HRP/H2O2 at 30℃for 3.5 h. The retanning agent R-1 was obtained. The structure and properties of the retanning agent R-1 were characterized by FTIR, NMR and GPC, and the results shown that the expected structure of graft copolymer was obtained. The application test indicated that the amount of retanning agent R-1 was 6%, the leather thickening rate of back-ridge, middle, belly was 20.31%,23.95% and 28.73%, respectively. The softness, grain condition and mechanical property of leather retanned by R-1 were better than that of comparison leather samples. The application test was excellent and reached the national standard. It was observed from SEM that R-1 has good dispersion effect to fiber and makes leather have excellent softness comparing with leather samples.Secondly, the preparation and application of phenol and aromatic amines copolymer were studied. The copolymer was synthesized by means of radical copolymerization of p-hydroxybenzoic acid (PHBA) and sulfanilic acid (SAA), and the reaction was catalyzed by HRP/H2O2. The effects of polymerization temperature, system pH, amount of monomers and HRP, H2O2 dropwise time and reaction time on structure and properties were investigated. The optimum reaction conditions were that in 150 mL solution composed of deionized water and phosphate buffer, the molar ratio of PHBA and SAA was 2:1, the amount of PHBA and SAA was 0.15 mol, the optimum temperature was 30℃, the reaction time was 3.5h, the amount of HRP was 5 mg, the dropwise time of 17 g 30% H2O2 was 2 h and the pH value maintained 8.0. Retanning agent R-2 without formaldehyde was obtained. The structure and properties of the copolymer were characterized by FTIR, NMR, GPC and PyGC-MS, and the mechanism of polymerization between PHBA and SAA was advanced. The applied results shown that when the amount of the retanning agent R-2 was 7%, the thickening rate of leather in the back-ridge, middle and belly were respectively 6.91%,7.95% and 11.72%, and the softness and grain of leather retanned by retanning agent R-2 were good. On the other hand, comparing with contrast leather, it has excellent softness, desired dyeing effect and particular style. R-2, which has sulfonic group, phenolic hydroxyl, carboxyl, amino and so on, combined with collagen by means of multiple hydrogen bonds, electrovalent bonds and a little covalent bonds. Thus R-2 has filling effect and retanning effect, and at the same time R-2 can endow the leather excellent softness and particular style. The innovation in this study was that two retanning agents, which were starch-vinyl graft copolymer retanning agent and PHBA and SAA copolymer retanning agent, were synthesized using HRP catalytic polymerization.