Preparation And Application Of Bacterial Cellulose And Gd Modified Polyacrylamid Composite Hydrogel

Hydrogels,with high moisture content,porosity and outstanding extensibility,and inherent electrical conductivity and biocompatibility,play an important role in the feild of flexible sensors and biomedical materials.Polyacrylamide（PAM）has the advantages of simple preparation and good biocompatibility,but the poor mechanical properties limit the application due.As a result,this paper intends to construct a double network（DN）hydrogel and nanocomposite（NC）hydrogel and introduces bacterial cellulose（BC）fragments to modify PAM hydrogel to meet the requirements for mechanical properties of flexible sensors and biomedical materials.（1）In this paper,Gd³⁺crosslinked SA was used to prepare Gd³⁺-PAM/SA composite hydrogel with high elongation at break.The effect of Gd³⁺on the properties of PAM/SA hydrogel was studied by testing the mechanical properties,water absorption,electrical and sensing properties.It was found that Gd³⁺-PAM/SA hydrogel showed a high elongation at break of 2200%,high stability in liquid environment,400%monitoring range and 1.48 strain sensitivity.In addition,its 10%strain response time was 130 ms and recovery time was 170 ms.At the same time,Gd³⁺-PAM/SA hydrogel showed high electrical stability in 1000 cycles under50%tension.（2）The broken BC reinforced PAM/CNT hydrogel was used to construct PAM/BC/CNT composite hydrogel,and the properties of PAM/BC/CNT composite hydrogel were evaluated.It is found that BC and CNT are entangled with each other and form network of PAM/BC/CNT hydrogel;the elongation at break of PAM/BC/CNT hydrogel is 1700%,and the breaking strength is 0.3 MPa.The composite hydrogel shows a sensing range of up to 800%and a sensitivity of 4.1%.At the same time,the sensor has excellent durability.PAM/BC/CNT hydrogels can be used to detect subtle human movements,recognize different letter features and identify different breathing scenes.（3）In this paper,the broken BC was added to PAM/SA hydrogel to construct PAM/BC/SA composite hydrogel.By studying the effects of BC on the mechanical properties,water absorption and wettability of PAM/SA hydrogel,the potential of its application in cartilage repair was evaluated.The results show that when the concentration of BC is 0.4 wt.%,the hydrogel has the compression strength of 0.45 MPa at 60%compression,and the hydrogel shows high compression recovery.The elastic modulus of PAM/BC/SA-0.4 is 0.23 MPa,which meets the requirement of 0.1-1.0 MPa compression modulus of cartilage.In summary,the Gd³⁺-PAM/SA and PAM/BC/CNT composite hydrogels studied in this paper exhibit good mechanical properties,have a wide sensing range and high sensitivity,and can meet the needs of flexible sensing.PAM/BC/SA composite hydrogel has good compression recovery and has the potential to be applied in cartilage tissue engineering.