Preparation And Properties Of Graphene/carboxymethyl Cotton Fiber Hydrogel

Cotton gauze is a traditional wound dressing for its low price and extensive use. However, the high crystallinity and not easy swelling characteristics of cotton fiber makes it quite poor water absorbent, thus the cotton fiber products subjected to surface treatment to improve its water absorption capacity has become a research focus in the field of high-performance medical dressing. Cotton fiber textiles treated by the carboxymethylation can make the surface of the fiber form the network structure of hydrophilic carboxyl methyl groups and the core of the fiber maintain the original structure, which can not only be gelatinous but also maintain a certain mechanical properties. Meanwhile,carboxymethyl cotton hydrogels have good biocompatibility and can be used as medical dressings of hydrogel-forming materials. Functional medical dressing is aimed to meet different use for the purpose of having a specific function. Graphene is a new carbon adsorbent material with good biocompatibility and high specific surface area, its theoretical specific surface area of up to 2600m2/g,which a small amount can achieve a good adsorption. The combination of graphene and carboxymethyl cotton hydrogels can extent their application in drug load field, as well as broaden their application area.In this paper, cotton gauze was chosen as the raw material. Firstly, the carboxymethylation was finished by the ethanol-borne method, and the single factor analytical method has been used to analyze the effect of the ratio of the weight of water to ethanol, concentration of the sodium hydroxide and molar ratio of sodium hydroxide to monochloroacetic acid. The influence of the different factors on the swelling behavior and mechanical properties of CMC hydrogel was investigated to find the best condition of carboxymethylation. Secondly, the carboxymethyl cotton hydrogels were treated with the graphene solution via ultrasonic vibration process. In this case, graphene was attached to thecarboxymethyl cotton hydrogels to prepare graphene/ carboxymethyl cotton composite hydrogels,then analyse the effect of concentration of graphene solution on the behavior of water absorption,mechanical properties and adsorption properties. Finally, through model fitting and calculation of dynamics and thermodynamic data to find the adsorption mechanism of carboxymethyl cotton hydrogels to sinomenine. The main conclusions of research are as follows:1)The optimum performance of carboxymethyl cotton hydrogel was obtained on the weight ratio of water/ethanol is 50/50, the concentration of sodium hydroxide is 10% and the molar ratio of sodium hydroxide and monochloroacetic acid is 1. Experimental results showed that under this circumstance,carboxymethyl cotton hydrogel can obtained the degree of substitution is 0.62, the water absorption is756%, the salt absorption is 625%, the dry breaking force is 133.63 N and the wet breaking force is7.9N, which provide the experimental and theoretical basis for the developing on the high-performance medical dressings used in the wound treatment.2)The carboxymethyl cotton hydrogels were treated with the graphene solution via ultrasonic vibration process under the best condition as previously mentioned. Experimental results showed that with the increasing concentration of graphene solution, the behavior of water absorption, mechanical properties and adsorption properties of carboxymethyl cotton hydrogels is continuously increased,when the concentration of graphene solution is 0.2mg/ml, the water absorption is 906%, the salt absorption is 623%, the dry breaking force is 118.88 N and the wet breaking force is 7.69 N, as well as sinomenine adsorption is up to 45mg/g.3)Through adsorption kinetics and adsorption thermodynamics to find the adsorption mechanism of carboxymethyl cotton hydrogels on sinomenine. Adsorption thermodynamics results showed that carboxymethyl cotton hydrogels on the adsorption of sinomenine fit the Freundlich isotherm model, which contained both physical adsorption and chemical heterogeneous. Adsorption kinetics results showed that carboxymethyl cotton hydrogels on the adsorption of sinomenine fit secondary dynamic equation, sinomenine adsorption involved electron sharing and transfer. The adsorption mechanism of carboxymethyl cotton hydrogels on sinomenine involved both heterogeneous multi-layer physical adsorption and electron sharing and transfer of chemical adsorption.