Enzymatic Preparation Of Carboxylated Viscose Fiber And Its Further Synthesis Of Functionalized Derivatives

Viscose fiber is a large amount of man-made fiber products made from natural cellulose such as wood cellulose,which is widely used in textile and other fields.However,viscose fibers exists some defects such as unctional group singleness,vulnerable to bacterial damage and so on.This paper aimed at improves its functional properties through the modification of the defects of viscose fibers.The existing chemical modification methods are generally characterized by poor specificity,harsh reaction conditions,narrow application range,and excessive waste water,which are not conducive to sustainable development.The functional groups on the surface of viscose fibers are hydroxyl groups,which have low reactivity.It is assumed that carboxylated viscose fibers can be prepared by oxidizing the hydroxyl group into the carboxyl groups with more reactivity.Enzymatic catalyzed chemical reaction has the characteristics of reaction conditions mild,high efficiency and specificity,harmless to human body and so on,which attract widely attention.It was reported that XXX XXX?XXX?can catalyze the oxidation of C1 of pyranoXXX to form gluconic acid.The cellulose on the surface of viscose fiber has a large number of reducing ends,and the semi-acetal hydroxyl in the terminal of pyranoXXX can be oxidized into carboxyl group under the catalysis of XXX.Therefore,the carboxylated viscose fiber is prepared.The carboxylated viscose fiber can become a kind of compound,which can be used as the starting material to synthesize a variety of functional fiber derivatives through modification reaction.It was reported that lipase can catalyse the reversed reaction direction and synthesizes esters and amides instead of hydrolyzing ester bonds in the non-aqueous medium.At present,there are neither studies on the preparation of carboxylated viscose fibers by XXX XXX nor the synthesis of functional derivatives of cellulose by enzymes in non-aqueous media.Based on this,on the one hand,silkworm pupa chitosan oligosaccharides,?-polylysine and oligomeric radish proanthocyanidins were respectively isolated and used as functional moleculars.On the other hand,the carboxylated viscose fiber was prepared with viscose fiber as raw material.Then the corresponding grafted fibers were synthesized by grafting silkworm pupa chitosan oligosaccharides,?-polylysine and oligomeric radish procyanidins.The aim of this paper is to provide a method and technology of whole-enzyme catalysis for the synthesis of functional viscose fiber derivatives for the fine chemical engineering discipline,and to enrich the empirical support of the biological catalysis science.The research conclusions obtained in this paper are summarized as follows:1.Study on preparation of carboxylated viscose fiberWith viscose fiber as raw material and XXX XXX as catalyst,carboxylated viscose fiber was prepared by carboxylation of the hemiacetal hydroxyl of viscose fiber.The formation of carboxylated viscose fiber was determined by FT-IR,SEM,XPS and NMR;The optimal condition for preparation of carboxylated viscose fiber was as follows:pH=6.0,the mass ratio of XXX/pretreatment viscose fiber of 0.06:1?w/w?,reaction temperature of 40^oC and reaction time was 4.5 h.2.Study on preparation of silkworm pupa chitosan oligosaccharide grafted with carboxylated viscose fiberSilkworm pupa chitosan oligosaccharide with deacetylation degree of 91.64±0.86%and Mw of?2.56±0.15??10³ g/mol was prepared with silkworm pupa as raw material;Preparation of silkworm pupa chitosan oligosaccharide grafted with carboxylated viscose fiber catalyzed by lipase in non-aqueous medium.The amino or hydroxyl groups in the silkworm pupa chitosan oligosaccharide were successfully reacted with the carboxyl of carboxylated viscose fibers to form amides or esters by characterization of FT-IF,TG-DTA,SEM and XPS analysis;The optimum condition of preparation of silkworm pupa chitosan oligosaccharide grafted with carboxylated viscose fiber was as follows:as isooctane as reaction solvent,the mass ratio of silkworm pupa chitosan oligosaccharide to carboxylated viscose fiber of 0.8:1?w/w?,reaction temperature 45 ^oC,the mass ratio of lipase to carboxylated to viscose fiber of0.07:1?w/w?,pH of 8.0,water content of 4.5%?w/w?;The results showed that the silkworm pupa chitosan oligosaccharide grafted with carboxylated viscose fibers showed good dyeing properties to anionic dyes,but poor dyeing properties to cationic dyes.Silkworm pupa chitosan oligosaccharide grafted with carboxylated viscose fiber showed good antimicrobial properties against gram-negative and gram-positive bacteria,especially gram-negative bacteria,with AP_?COS?values of 59.12%and 43.83%.3.Study on the preparation of?-polylysine grafted with carboxylated viscose fiberThe?-polylysine with average molecular weight of 4443 Da was separarted with commercially available?-polylysine with average molecular weight of 9508 Da as raw material;Preparation of?-polylysine grafted with carboxylated viscose fiber catalyzed by lipase in non-aqueous medium.?-polylysine was succseefully grafted with carboxylated viscose fiber proved by FT-IR,SEM and XPS analysis;The optimum condition of preparation of?-polylysine grafted with carboxylated viscose fiber was as follows:as isooctane as reaction solvent,reaction temperature 45 ^oC,the mass ratio of lipase to carboxylated to viscose fiber of 0.08:1?w/w?,pH of 8.0,water content of 4.5%?w/w?;The results showed that?-polylysine grafted with carboxylated viscose fiber had good dyeing properties for both anionic and cationic dyes,especially for anionic dyes.The moisture absorption of?-polylysine grafted with carboxylated viscose fiber increased with the increase of grafting rate.In addition,?-polylysine grafted with carboxylated viscose fiber showed good antimicrobial properties against gram-negative and gram-positive bacteria,especially gram-negative bacteria,with AP_?PL?values of66.67%and 55.09%,respectively.4.Study on preparation of oligomeric radish procyanidin grafted with carboxylated viscose fiberChitosan-based crosslinked phenylethylamine resin?PMCCR?was prepared with silkworm pupa chitosan and 2-phenylethylamine as raw material;Oligomeric and polymeric radish procyanidins was separated by methanol and PMCCR with red radish as raw material;Polymeric radish procyanidins was degraded by N-acetylneuraminate lyases.The results showed that,the proportion of procyanidins monomers?or oligomers?in the product increased to 11.2%,while polymers was reduced to 47.3%after degradation;Preparation of oligomeric radish procyanidin grafted with carboxylated viscose fiber catalyzed by lipase in non-aqueous medium,and the gratfting of oligomeric radish procyanidin was characterized by FT-IR,SEM and XPS analysis;The optimum condition of preparation of oligomeric radish procyanidin grafted with carboxylated viscose fiber obtained by single factor experiment and orthogonal experiment was as follows:as isooctane as reaction solvent,reaction temperature 45 ^oC,the mass ratio of lipase to carboxylated to viscose fiber of 0.08:1?w/w?,pH of 8.0,water content of 4.5%?w/w?;The oligomeric radish procyanidin grafted with carboxylated viscose fiber had good antibacterial properties against gram-negative and gram-positive bacteria,especially gram-negative bacteria,with AP_?PRO?value of 50.82%and 38.34%.The oligomeric radish procyanidin grafted with carboxylated viscose fiber had good anti-ultraviolet performance,which was in line with the national standard for evaluating the anti-ultraviolet performance of textiles.