| Polyurethanes are widely used in the manufacture of footwear,apparel,bags,and automotive interiors due to their excellent properties.However,the raw materials are mainly derived from non-renewable petrochemical resources,and the polyurethanes,especially waterborne polyurethanes(WPU),generally have poor water resistance and antibacterial properties.With the implementation of sustainable development strategy and "carbon peaking and carbon neutrality"goals,employing renewable resources to replace petrochemical resources to prepare "green" and high-performance WPU has attracted the attention of researchers.In this thesis,modified castor oil-based polyol(CM)was prepared from castor oil(CO)through thiol-ene click reaction,and CM was used as crosslinkers to prepare castor oil-based waterborne polyurethane(CMWPU).Then,CMWPU was grafted to CMWPU to further improve the water resistance and impart certain antibacterial properties.Finally,Ti3C2Tx nanosheets were introduced into CMWPU-AP to further improve the antimicrobial properties of castor oil-based WPU,and the effect of the structure of castor oil based WPU on the properties was systematically studied.The main research works are as follows:(1)In order to investigate the effect of castor oil-based crosslinker CM on the properties of castor oil-based waterborne polyurethane,a multifunctional castor oil-based polyol CM(with a maximum hydroxyl value of 371 mg KOH/g)was prepared by the thiol-ene click reaction using castor oil as raw material,and its optimal preparation condition was determined.The modified castor oil-based waterborne polyurethane CMWPU with a solid content of about 30%was prepared by CM as crosslinkers.The results showed that the prepared CMWPU emulsions exhibited good storage stability when the dosage of CM was no more than 20%.When the dosage of CM was 20%,the prepared CMWPU film had the best comprehensive properties,the CMWPU film had a tensile strength of 10.8 MPa,glass transition temperature of 45℃,water absorption rate of 16.12%,contact angle of 87.4°,gel content of 87.37%,and showed UV shielding performance.It is showed that the CMWPU films had improved mechanical properties and water resistance.(2)In order to further improve the water resistance of CMWPU and impart its certain antibacterial properties,CMWPU-AP emulsion with a solid content of about 30%was prepared by introducing AP into the CMWPU system.The results showed that the prepared CMWPU-AP emulsion exhibited good storage stability when the dosage of AP was no more than 50%.When the dosage of AP was 30%,the prepared CMWPU-AP film had the best comprehensive performance with a tensile strength of 11.34 MPa,glass transition temperature of 75.3℃,water absorption rate of 2.18%,contact angle of 96.9°,gel content of 88.67%,and the film could inhibited the reproduction of E.coli and S.aureus.The inhibition rate of E.coli and S.aureus was 94.73%and 66.34%,respectively.It is showed that the mechanical properties,water resistance and glass transition temperature of CMWPU-AP material were significantly improved and exhibited a certain degree of antibacterial performance.(3)To further improve the antimicrobial performance of CMWPU-AP,Ti3C2Tx nanosheets were introduced into the CMWPU-AP system by means of the physical blending method.When the dosage of Ti3C2Tx was 0.75%,the prepared CMWPU-AP/Ti3C2Tx film had the best comprehensive performance.The CMWPU-AP/Ti3C2Tx film had a tensile strength of 9.33 MPa,elongation at break of 1.07%,water absorption of 1.19%,contact angle of 105.1°,glass transition temperature of 61.7℃.In addition,the material had excellent UV shielding performance,and showed good stability in 1 mol/L HCl solution and saturated salt water,but could degraded in alkaline solutions.The inhibition rates of E.coli and S.aureus was 99.41%and 98.03%,respectively,The introduction of Ti3C2Tx provided the material with excellent photothermal properties,and thus the CMWPU-AP/Ti3C2Tx-0.75 composite films exhibiting high inhibition rates for both E.coli and S.aureus after photothermal treatment,which indicated that the CMWPU-AP/Ti3C2Tx material had desirable water resistance and antibacterial properties. |
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