Preparation Of Chitosan Based Composite Microcapsules And Its Application In Textiles

Functional textiles are becoming more and more popular,but if functional active substances（phase change materials,dyes,fragrances,etc.）applied directly to textiles,it will cause problems such as low utilization and poor durability performance.Therefore,the encapsulation of these active substances by microencapsulation technology can improve their utilization on textiles and solve the problem of energy waste.At present,the single function textiles in the market cannot meet people’s needs,and do not conform to the concept of green and sustainable development,so the preparation of multifunctional microcapsules based on biomass and the application on textiles will become the main development direction of the textile market.Based on it,we chose biomass material chitosan as wall material and different active substances as core material to study the preparation of functional composite microcapsules and their application performance on textiles.The overall research content of this paper is mainly to firstly use chitosan as shell material,prepare chitosan microcapsules by single condensation method,and then the amino groups of chitosan molecules are used to graft nanocapsules or nanoparticles with different performances to obtain functional composite microcapsules.Then,the prepared functional microcapsules were treated onto the textiles,which endowed the textiles with photochromic,antibacterial,energy storage,superhydrophobic and other properties.The research parts and conclusions of this paper are mainly divided into three aspects:（1）Preparation of double-compartment chitosan composite microcapsules and their application in textilesChitosan microcapsules were firstly prepared by single coacervation method using chitosan as the wall material and solid paraffin as the core material.Then,styrene nanocapsules with internally encapsulated photosensitive dyes（spiro[1,3,3-trimethylindol-（6’-nitrobenzodihydrofuran）]）were prepared by the microemulsion method.The epoxy group on the glycidyl methacrylate（GMA）molecule was used to graft the styrene photochromic nanocapsules onto the surface of chitosan microcapsules by ring-opening reaction with the amino group on the chitosan molecule to obtain double-chambered chitosan composite microcapsules.The prepared composite microcapsules were then added to silicone resin and coated onto the surface of cotton fabric using the coating method to obtain multifunctional fabric.The morphology of the prepared composite microcapsules was characterized by SEM,which demonstrated that the microcapsules had a strawberry-type double-chambered structure.The encapsulation rates of chitosan microcapsules and styrene photochromic nanocapsules were calculated by TGA,and the encapsulation rates of 65.42%and 83.87%were obtained,respectively.The multifunctional fabrics were further demonstrated to have thermal insulation performance by thermal imaging analysis.The Gram-negative bacterium E.coli and the Gram-positive bacterium S.aureus were selected as indicator bacteria and the antibacterial performance of the multifunctional fabric was characterized by the oscillation method,and the calculated results showed that the inhibition rates of the functional fabric against these two bacteria were 77.7%and97.2%,respectively.In addition,the multifunctional fabric could turn purple under UV light irradiation,and showed different shades of purple under different intensity of sunlight.（2）Preparation of Zn O/chitosan composite microcapsules and their application in textilesThe Zn O nanoparticles with superhydrophobic properties were firstly obtained by surface modification of Zn O nanoparticles usingγ-methacryloxypropyltrimethoxy silane coupling agent（KH570）and 1H,1H,2H,2H-perfluorooctyltriethoxysilane（PFOTS）.The modified Zn O particles were then grafted onto the surface of chitosan phase change microcapsules by Michael addition reaction to obtain Zn O/chitosan composite microcapsules.The Zn O/chitosan composite microcapsules were finished onto the surface of wool fabric by reducing the disulfide bonds of the scale layer of wool fabric using tricarboxyethylphosphine（TCEP）,followed by the thiol-ene click reaction between the double bonds on the composite microcapsules and the sulfhydryl groups on the wool fabric.The morphological characterization of the composite microcapsules by SEM demonstrated that the modified Zn O particles were successfully loaded on the chitosan microcapsule surface.Due to the encapsulated phase change material,the multifunctional wool fabric has good energy storage and thermal insulation performance with a temperature difference of 3～5°C.The surface of the functional wool fabric is also superhydrophobic,with the static water contact angle of water droplets on the surface of the fabric greater than 150°and the rolling angle less than 10°;in addition,the functional wool fabric also has antibacterial performance,with98.9%and 97.2%inhibition rates for S.aureus and E.coli,respectively.After the antibacterial experiment,it was found that the antibacterial rate of composite microcapsules was higher than that of chitosan microcapsules,which was due to the fact that the modified zinc oxide also had antibacterial properties,and the composite with chitosan could play synergistic antibacterial effect.（3）Preparation CO₂-responsive sustained release chitosan microcapsules and their application in textilesThe modified chitosan was obtained by adding dimethyl aminoethyl methacrylate（DMAEMA）into the molecular structure of chitosan.CO₂-responsive sustained release chitosan microcapsules were prepared with modified chitosan as wall material and lemon essential oil（LFO）as core material by single coacervation method.The multi-functional non-woven fabric or viscose fiber with antibacterial and CO₂ responsive fragrance release dual performances can be obtained by dipping and rolling the microcapsules onto the surface of non-woven fabric or viscose fiber.The results of SEM showed that the microcapsules had regular spherical shape with an average particle size of about 5μm.The encapsulation rate of LFO was calculated as 30.34%by TGA test.The sustained release performance of the microcapsules was tested by UV absorption photometer.The results showed that the chitosan microcapsules encapsulated with LFO had a sustained release performance and a faster sustained release under CO₂atmosphere.The antibacterial activity of multifunctional nonwoven fabric was tested.According to the antibacterial results,the antibacterial activity of chitosan microcapsules encapsulated with LFO was superior to that of chitosan,because LFO also had certain antibacterial activity,and the antibacterial activity of multifunctional nonwoven fabric against S.aureus and E.coli was 98.3%and 95.7%,respectively.