Preparation Of DEET Microcapsules Based On PLA And Its Application In Cotton Fabric

With the improvement of economic level,people's demands for quality of life are also getting higher and higher.For textiles,their basic functions have been difficult to meet consumer demand.Therefore,in order to increase the added value of textiles,the development of functional textiles has become more and more popular in recent years.Among them,the functional finishing agent is finished on the fabric by the sustained-release microcapsule technology,so that the fabric can achieve a variety of long-lasting functions such as mosquito repellent,aroma,antibacterial,etc.Research has increasingly become a research hotspot.The principle of the microcapsule technology is to enclose the volatile active substance in a micro-container so that the active substance is released at a slow speed.The microcapsules can be firmly attached to the fibers by means of printing,padding,dipping,coating,etc.by means of adhesives,thereby increasing the service life of the functional textiles.In this paper,the solvent evaporation method is used to polylactic acid as the wall material and DEET as the core material.The preparation process and the sustained-release properties of the microcapsules are discussed in detail.The method of padding is used in conjunction with the adhesive and hot curing technology.The microcapsules were finished on cotton fabrics,and the finishing process was discussed to prepare mosquito repellent fabrics with better durability.The main research content of this topic includes the following aspects:(1)Preparation of polylactic acid/ DEET microcapsules: Dichloromethane wasused as the solvent,polylactic acid was used as the wall material,and DEET was used as the core material.The microcapsules were prepared by solvent evaporation.First,the microcapsule particle size and coating rate were used as indicators,and the single factor method was used to design the experiment.The solvent content,the ratio of the wall core,the ratio of the emulsifier,the shear rate,and the stirring speed were used to investigate the particle size and the coating rate.Impact.Orthogonal analysis was used to design the experiment and optimize the preparation conditions.The study shows that the optimum conditions are: the amount of methylene chloride is 20 ml,the ratio of wall core is 1:1,the ratio of emulsifiers Tween80 and Span80 is 1:1,the shear rate is 13000r/min,and the stirring speed is 900r/min..The average particle size of the microcapsules prepared under the optimized process was 242.8 nm,the PDI was0.319,the coverage was 38.5%,and the drug loading rate was 12.3%.The particle size of the microcapsules is normally distributed,and the particle size distribution is concentrated between 100 and 400 nm.(2)Morphology and performance characterization of polylactide/ DEET microcapsules: The morphology of microcapsules was characterized by field emission scanning electron microscopy.The structure of microcapsule was characterized by ir spectra,and the thermal stability of microcapsule was measured by thermogravimetric analyzer.At the same time,its sustained release performance at different temperatures was analyzed.The results show that the microcapsules have a good balling effect and a uniform particle size distribution.Infrared analysis showed that DEET was successfully coated into the wall material.By comparing the thermogravimetric(TG and DTG)analysis of the DEET and drug-loaded nanocapsules,it was shown that the encapsulated microcapsules can effectively reduce the influence of the external temperature on the core material of the capsule,so that it has a good thermal stability,thereby reducing the core material.The speed of Slow-release microcapsules in different temperature curve indicates that the environment temperature affects the release rate of microcapsules,generally the higher the temperature,the release of thecore material,the more acute,and with a certain interpretation of the phenomenon,and the phenomenon of sudden release will manifest with the increase of temperature.(3)Finishing of cotton fabric with acid/DEET microcapsules and study on the properties of the cotton fabric finished by microcapsules: The cotton fabrics were microcapsulated using padding method.The effects of microcapsule dosage,binder dosage,baking temperature and curing time on the properties of the finished cotton fabrics were discussed.influences.The content of the active ingredients on the fabric,the breaking strength of the finished fabric,the wrinkle recovery angle,and the air permeability were measured.The best microcapsule finishing process is:microcapsule 20g/L,waterborne polyurethane 60g/L,baking temperature 130°C,baking time 3min.The washed fabrics were characterized by water resistance test and their sustained-release properties were explored.The experimental results showed that fabrics added with waterborne polyurethane were more resistant to washing and retained 69.0% of active ingredient content after 15 times of water washing.The sustained release properties of the microcapsules are basically the same.The finished fabric is basically the same as the original style.