Application Of Quaternary Ammonium Compounds-Nano Clay Composites In Long-term Anti-mildew Of Bamboo

Bamboo and its products are easy to mildew,and often need anti-mildew treatment.However,mildew preventive will be leached in the long-term outdoor use process,due to the influence of environmental factors such as wind and rain,which will reduce the protective life of bamboo and its products.Therefore,efficient and long-term are important research directions of bamboo protection.In this study,aiming at the phenomena that bamboo is easy to mildew and mildew preventive is easy to lose,natural nano-clays were used to load mildew preventive and applied in the field of bamboo protection.Quaternary ammonium compounds(QACs)are a kind of organic mildew preventive and cationic surfactant.It is widely used in bamboo or wood preservation and mildew prevention.However,it is soluble in water and has poor thermal stability.There are problems of durability and service life in the application process.Halloysite(HNT)which has hollow tubular ructure and Montmorillonite(MMT)which has lamellar structure,are both have good loading and adsorption properties for drugs.Two kinds of nano-clays are widely used in the field of drug sustained release,and their research experience also inspires us to apply them to bamboo protection.In this paper,two commonly used QACs mildew preventives,Dodecyl Dimethyl Benzyl Ammonium Chloride(BAC)and Didecyl Dimethyl Ammonium Chloride(DDAC),were used to prepare QACs/nano-clay composites,which HNT and MMT were used as carriers.Thermal stability and release characteristics of QACs in nano-clay were investigated.QACs-nano clay composites were applied to the modification of wood wax oil.The anti-mildew and leaching resistance of QACs were explored.The main research contents and conclusions are as follows:1)Preparation and characterization of QACs-nano clay composites.QACs were loaded into the cavity of HNT by vacuum pressure method,and were inserted into the interlayer of MMT by cation exchange.Infrared spectrum analysis showed that QACs were successfully loaded into nano-clays.quaternary ammonium salt could be inserted into the interlayer of MMT,and its alkyl chain increased the interlayer spacing of MMT from 1.15 nm to 1.75 nm and 2.85 nm,respectively,while QACs could not be inserted into the interlayer of HNT.nitrogen adsorption test showed that quaternary ammonium salt successfully entered the inner cavity of halloysite.2)Performance evaluation of QACs-nano clay composites.After modification of QACs,The hydrophobicity of nano-clays is obviously improved.Thermogravimetric analysis showed that nano-clays have a certain protective effect on QACs,which improved its thermal stability significantly.The loads of BAC and DDAC in HNT were 8.55 % and 10.61 %,respectively,and 22.5 % and 30.9 % in MMT.The accelerated release test showed that nano-clays had a good slow-release effect on QACs.Korsmeyer-Peppas model was used to simulate the release of QACs and found that the release of QACs was mainly due to the dissolution.The inhibition zone test showed that the QACs-nano clay composites could maintain the original antifungal activity,and had certain inhibition effect on mould fungi and stain.3)The application of QACs-nano clay composites in wood wax oil: The addition of QACs can improve the stability of nano-clays in wood wax oil.The addition of nano-materials can reduce the glossiness of bamboo coating,without negative impact on color,and improve the hydrophobicity of bamboo surface.QACs-nano clay composites can give wood wax oil Good anti-mildew properties,and leaching resistance of QACs was significantly improved.