Preparation Of Cellulose-based Functional Hydrogel And Its Application In Dressings And Sensors

Hydrogels are a kind of high molecular polymer with three-dimensional network structure and swelling properties.It combines the properties of water absorption,water retention,drug release and conductivity to become a multifunctional composite soft material.Cellulose and its derivatives are a kind of green and environmentally friendly biomass resources that are easy to modify,have good biocompatibility and degradability,and are often used as important raw materials for hydrogels.Traditional hydrogels have disadvantages such as poor mechanical properties,poor biocompatibility,instability and easy damage.This paper selected carboxymethyl cellulose（CMC）and water-soluble cellulose acetate（WSCA）as raw materials to prepare three different hydrogels,and studied their structural properties.The details are as follows:1.Using carboxymethyl cellulose（CMC）,acrylic acid（AA）,aluminum chloride（AlCl₃·6H₂O）,a double-network interpenetrating structure hydrogel(CMC-Al³⁺-PAA)was synthesized by one-pot method,and the structure,morphology,swelling rate,self-healing and electrical conductivity of the hydrogel were studied experimentally.The experimental results showed that the swelling rate of CMC-Al³⁺-PAA hydrogels decreased with the increase of CMC content.CMC-Al³⁺-PAA hydrogels also had good mechanical properties.When the addition amount of CMC was 3%,the tensile strength was 249 k Pa,and it can withstand 85%deformation and compression cycles without breaking,and the deformation was completely recovered after pressure releasing.CMC-Al³⁺-PAA hydrogels had excellent self-healing properties,reaching a healing equilibrium state within 40 minutes,and the healing efficiency was 93%.CMC-Al³⁺-PAA hydrogels as a strain sensor responded quickly to human movement,such as bending of elbows,wrists and fingers,and showed good stability.It can also detect changes in ambient temperature and had a certain temperature sensitivity,which had great application potential in future flexible and wearable temperature-sensitive sensor devices.2.Water-soluble cellulose acetate（WSCA）was prepared from cotton linters,and PVA-FBA was obtained by acetal reaction of polyvinyl alcohol（PVA）and 4-carboxybenzaldehyde（FBA）under acidic conditions.Organic hydrogels（WSCA/PVA-FBA（7:3,8:2,9:1,10:0））were physically cross-linked with WSCA and PVA-FBA in different DMSO/H₂O solvents.The structure,morphology,mechanical properties,antifreeze and electrical conductivity of the organic hydrogels were studied.The results showed that the organic hydrogel had good mechanical properties.When the DMSO/H₂O and the WSCA content were 7:3 and 2%,the tensile strength and elongation at break of the organic gel were 0.85MPa and 719%.WSCA/PVA-FBA（7:3）organic hydrogels maintained their flexibility and conductivity at-80°C to monitor human motion information with high sensitivity,stability,and durability.WSCA/PVA-FBA organic hydrogel had good skin-like characteristics,which can trigger the capacitive screen of electronic products,and will have the application prospect of human-computer interaction,personal medical care and sports monitoring in harsh environments.3.Carboxymethyl cellulose（CMC）and polyethylene glycol（PEG）were modified to CMC-ADH and PEG-FBA through adipic acid dihydrazide（ADH）and 4-formyl benzoic acid（FBA）.The CMC-ADH/PEG-FBA hydrogels were synthesized by the principle of dynamic reversibility of the acylhydrazone bond.The structure and morphology,swelling rate,drug release ability,antibacterial and biocompatibility of the hydrogels were studied.The results showed that CMC-ADH/PEG-FBA hydrogels could self-heal in 24h and the swelling rate in PBS buffer was 41.5～83.2%.CMC-ADH/PEG-FBA hydrogels had good ability of drug release with the highest release rate of 76.9%.Bacterial culture experiments showed that the drug-loaded hydrogels had good antibacterial properties,and the diameter of the inhibition zones against E.coli and S.aureus was 12 and 11 mm respectively.In vitro co-culture of L929 cells and hemolysis experiments showed that hydrogels had good biocompatible.The hydrogels had hemostatic effect and better promotion effect on wound healing in the rat living body.The multifunctional CMC-ADH/PEG-FBA hydrogel is an ideal choice for drug delivery vehicles and wound dressings.