Synthesis Of Chitosan Biguanidine Hydrochloride And Its Application In Antimicrobial Finishing And Dyeing Of Wool Fabric

All along,people are putting in a lot of effort to study various types of antimicrobial agents, whether organic or inorganic antimicrobial agents have made considerable progress.Chitosan is a polycationic compound,at the same time,because of its biodegradability,biocompatibility and environment-friendly nature,which is also more and more popular as a natural antimicrobial agent. But the high molecular weight of chitosan,as well as the presence of amino group,leading to a stronger intermolecular hydrogen bonding,making poor solubility of chitosan,has seriously affected many applications of chitosan.Meanwhile,chitosan has a complex double-helix structure, and -OH,-NH₂ in its structure both have strong reactivity,which can be carried out a variety of chemical modification under appropriate conditions,to improve its solubility,such as,quaternized, carboxyalkylated,guanidinylated,and sulphonyl and so on.In addition,the introduction of the relevant functional groups also can enhance the antimicrobial activity of chitosan.For the above reasons,this research used chitosan and dicyandiamide as raw materials to prepare chitosan biguanidine hydrochloride,studied the reaction time,the reaction temperature, the pH value,the molar radio of chitosan and dicyandiamide and other factors' influences on the reaction yield of chitosan biguanidine hydrochloride.This research used L₉(3⁴) orthogonal experimental to determine the optimal synthesis process.The structure of chitosan biguanidine hydrochloride was characterized by Fourier transform infrared spectroscopy and ¹³CNMR spectra. The substitution degrees of chitosan biguanidine hydrochloride were confirmed by elemental analysis.The preparation of chitosan biguanidine hydrochloride was simple and convenient.And it could be applied to wool fabric through padding-drying-curing process.The effect of process conditions on antimicrobial activity,washability,dyeing performance was studied.The main research papers were summarized in the following statements.1.Chitosan and dicyandiamide were used as the raw materials to prepare water-soluble chitosan biguanidine hydrochloride.The results of single-factor experiments and orthogonal experiments showed that the optimal synthesis conditions were:the molar radio of chitosan and dicyandiamide was 1:5,the reaction temperature was 90℃,the reaction time was 2h, and the reaction system pH value was 2.The minimal inhibitory concentrations on E.coli and S.aureus were:1.4mg/mL and 1.2mg/mL.2.Chitosan biguanidine hydrochloride was applied to wool fabric,through padding-drying-curing process.The results of the effect of various processing conditions on antimicrobial activity of wool fabric showed that the optimal finishing process of chitosan biguanidine hydrochloride on wool fabric:wool fabric was pretreated by hydrogen peroxide, the amounts of antimicrobial agent was 20%(o.w.f.),the amounts of citric acid as the crosslinking agent was 20%(o.w.f.).Excellent antimicrobial wool fabric was got on the condition of one dipping-one padding(With liquid rate of 80%),drying temperature was 70℃for 4min,and the final curing temperature was 130℃,the obtained wool fabrics owed the best antimicrobial activity and washability.After five times standard washings in accordance with AATCC61-2A,the antimicrobial value was still up 2.3.Through the comparing experiments of antimicrobial activity of wool fabrics treated by chitosan biguanidine hydrochloride and chitosan,the results showed that chitosan biguanidine hydrochloride treated wool fabric had better antimicrobial activity and washability than chitosan treated wool fabric.3.The wool fabrics were treated by chitosan biguanidine hydrochloride and then dyed using acid dyes,premetalized dyes and reactive dyes.The results showed that the treated wool fibers had significantly improved K/S value with different degrees;especially the results of premetalized dyes and reactive dyes for wool are obvious.The 20%chitosan bignanidine hydrochloride treated wool fabrics dyed with 3%(o.w.f.) dye produced the same or higher color yield than that of untreated fabrics dyed with 4%(o.w.f.) dye,meanwhile the dyeing percentage was also be a manifestation of this upgrade.Also,there were no significant influences on color fastness,such as the dry and wet rubbing fastness,wash fastness,which were still determined by the properties of the dye itself.