Preparation And Properties Of Modified Polylactic Acid Meltblown Material For Medical Dressing

Human life and health have always been put in the first place.When human skin is injured or damaged,medical dressings are needed to cure and protect it.With the progress of technologies and the growth of human demand,medical dressing has become functional and harmless,and the research on the functional modification of medical dressing has become more important.As an environment friendly and easily available polymer material,polylactic acid(PLA)has good biocompatibility.It has good air permeability and non-toxicity after being prepared as melt-blown material,which meets the basic requirements of medical dressings.This work mainly attempts to modify a polylactic acid melt blown material to be multi-function,and apply it to be material of medical dressings,so as to provide a new method for the preparation of multi-functional medical dressing.First of all,the PLA melt blown material provided by a laboratory was used as the main body of modification,and the hydrophilic modified polylactic acid(PLA(P))melt blown material was obtained by low temperature oxygen plasma treatment with different power and different modification time.The effects of different power and time on the properties of PLA(P)melt blown material were studied.the results showed that the comprehensive performance of PLA(P)was the best when the treatment power was80 W and the treatment time was 40 s;and the chemical structure and crystal morphology of PLA(P)were almost unchanged before and after modification;the air permeability and softness of PLA(P)melt blown material were obviously improved,the air permeability increased at the most 37.7%,and the softness increased at the most55.9%,but the mechanical properties were unchanged;from the analysis of water contact angle and liquid diffusion properties,it can be concluded that the hydrophobic surface of PLA melt blown material changed into PLA(P)hydrophilic surface,and its hydrophilicity was significantly improved;the liquid diffusivity of PLA(P)melt blown material in deionized water and sheep whole blood increased at least 5 times;and scanning electron microscopy showed that low temperature plasma modification caused more pores and grooves on the surface of PLA(P),which was beneficial to improve air permeability,softness and adhesion.Secondly,in order to further endow PLA(P)with antibacterial and coagulation properties,carboxymethyl chitosan(CCS)was modified by quaternization.The specific process was adopted to modify CCS with 2,3-epoxypropyl trimethyl ammonium chloride(GTA)as modifier to prepare quaternized carboxymethyl chitosan(QCCS).QCCS with different degrees of substitution(0.5 g,1.0 g,1.5 g,2.0 g)was obtained by changing the amount of GTA.Nuclear magnetic hydrogen spectrum analysis showed that QCCS,with a degree of substitution of 19.4%,34.8%,52.2% and 53%;bacteriostatic ring experiment and comparison QCCS than CCS to S bacteria(Staphylococcus aureus)and E bacteria(E.coli)better antimicrobial properties than CCS.PLA(P)melt blown material(PLA(P)-QCCS melt blown material)was obtained by impregnating PLA(P)melt blown material with different degrees of substitution and concentration of QCCS solution.The experimental analysis showed that the degree of substitution of QCCS was 19.4% and the concentration was 1.0%(mass fraction).At this time,the prepared PLA(P)-QCCS melt-blown material had good air permeability and softness,while ensuring certain mechanical properties;and the structure and crystal morphology of PLA(P)-QCCS melt-blown material had no obvious change compared with PLA(P)melt-blown material;the hydrophilicity of PLA(P)melt blown material loaded with QCCS was improved to a certain extent,and the static contact angle of PLA(P)melt blown material decreased by at the most 40.1%.Compared with PLA(P)melt blown material,the liquid diffusivity of deionized water and sheep whole blood was improved by 27.8% and 49.8%;respectively,and the clotting time of 3 min was shortened compared with the original material;After modification,the inhibition rate of S and E bacteria can reach more than 90%.Finally,because QCCS on the surface of PLA(P)melt-blown material was uneven and difficult to be adsorbed,it is necessary to introduce a kind of adhesive.In this work,different concentrations of dopamine hydrochloride(DA)were used as binders to treat PLA(P)melt blown materials,and then QCC was loaded to prepare PLA(P)-QCCS melt blown materials(QCCS/DA/PLA(P)melt blown materials).The effect of DA concentration on the content of QCCS on the surface of PLA melt blown material was studied,so it is necessary to introduce a kind of adhesive.The results showed that when the concentration of DA was 0.2%(mass fraction),the comprehensive properties of QCCS/DA/PLA(P)melt blown materials was optimum.Compared with PLA(P)melt blown materials,the air permeability and softness of QCCS/DA/PLA(P)were slightly decreased,but the mechanical properties were improved;the hydrophilicity was significantly improved,and the contact angle analysis showed that the optimal QCCS/DA/PLA(P)melt blown material formed a super hydrophilic surface,and the liquid diffusivity of deionized water and sheep whole blood could be increased by 6.6%;after modification,the clotting time in vitro was shorten 2 minutes;and the inhibition rate of S bacteria and E bacteria could reached at 99.0%;after introducing DA as binder,the load of QCCS on PLA melt-blown material could be increased by 2 times.At the same time,it could be found from the scanning electron microscope that the dispersion of QCCS on the fiber surface became uniform,which achieved the purpose of introducing DA.