Preparation And Characterization Of Nano-ZnO Hydrogels For Bamboo Mildew

Bamboo is easy to mildew,which directly affects the use value and economic value of bamboo products.Although domestic and foreign scholars have done lots of studies on bamboo anti-mildew and achieved good results,the existing anti-mildew treatment technology hasn’t realized the long-lasting anti-mildew of bamboo.In order to overcome this problem,this paper uses N-isopropylacrylamide(NIPAm)as a base material,the nano-ZnO particles with strong bactericidal properties are encapsulated into the hydrogels to prepare temperature-sensitive nano-antibacterial hydrogels.Finally,the composite bamboo material is gotten by the nano ZnO composite hydrogel treatment.The controlled release of nano-ZnO is achieved by the temperature sensitive property of the composite hydrogel,thereby achieving the long-lasting effect of bamboo.The mian work and conclusions are listed as follows:(1)The nano-ZnO was produced via the in situ method in poly(N-isopropylacrylamide-co-acrylic acid)(P(NIPAm-co-AAc))hydrogel.The results show that nano-ZnO particles were monodispersed in the P(NIPAm-co-AAc)hydrogel.The concentration of the nano-ZnO was higher in the ZnO/P(NIPAm-co-AAc)hydrogel.The swelling properties of the ZnO/P(NIPAm-co-AAc)hydrogel were better than the ZnO/PNIPAm hydrogel,while the deswelling properties were poorer.And ZnO/P(NIPAm-co-AAc)hydrogel has temperature response at 35 ~oC.The hydrogels that contained more ZnO nanoparticles demonstrated greater antibacterial properties against Trichoderma viride and Penicillium citrinum of bamboo,while the all of the hydrogels had much less antibacterial activity against Aspergillus niger.(2)At room temperature,adding a nano ZnO dispersion or dispersant(sodium dodecylbenzene sulfonate(SDBS);cetyltrimethylammoniumbromide(CTAB);polyvinylpyrrolidone(PVP))/nano-ZnO successfully prepared ZnO/PNIPAm composite hydrogel by free radical polymerization method.The results show that the ZnO/PNIPAm composite hydrogel prepared by adding nano-ZnO dispersion has the smallest particle size and the most stable,and the nano-ZnO is most uniformly dispersed in the gel.The addition of nano-ZnO dispersion or dispersant didn’t change the LCST value of ZnO/PNIPAm composite hydrogel,and the phase transition temperature was still around 32°C.The solid content of the ZnO/PNIPAm composite hydrogel was 1.03 wt%.(3)The bamboo strips were treated to atmospheric pressure impregnation and pressure impregnation treatment by ZnO/PNIPAm composite hydrogel having a solid content of 1.03 wt%.The results showed that the drug loading rate of bamboo strips increased with the immersion time and the pressure of the pressing.The process parameters of optimum immersion treatment are an applied pressure of 0.3 MPa and an immersion time of 3 h.Compared with atmospheric pressure impregnation,pressure impregnation can significantly increase the drug loading rate of bamboo without changing the internal structure of bamboo.The anti-mildew effect of bamboo strips after pressure impregnation treatment with nano-ZnO composite hydrogel was significantly improved.