Design and preparation of adhesion-enhanced EG-BPSQ/SiO2 antifogging and antireflective coatings
Thioether-ester-bridged sesquioxane(EG-BSQ)precursor was prepared from mercaptoene click reaction of ethylene dimethacrylate(EGD)and 3-mercaptopropyl trimethoxysilane(MPTMS)[n(EGD)∶n(MPTMS)=1.0∶2.4]at the catalysis of 1,8-diazecyclic[5,4,0]undeca-7-ene(DBU)under N2 atmosphere,and then reacted with acetic acid and NaOH to obtain EG prepolymer(EG-BPSQ),which was further reacted with SiO2 sol through in situ hydrolytic polycondensation to synthesize S-EG composite sols.Finally,EG-BPSQ/SiO2(S-EG for short)composite coatings were obtained via impregnation pulling method,and characterized by FTIR and SEM.The effects of V(EG prepolymer)∶V(SiO2 sol)and treatment temperature on static water contact angle,transmittance,adhesion,anti-fog and anti-reflection performance of S-EG composite coatings were investigated.The results showed that the introduction of EG-BPSQ into SiO2 sol enhanced the bonding between SiO2 nanoparticles as well as coating and substrate,EG-BPSQ displayed the effect of"bonding"and"pore formation"at the same time.When V(EG prepolymer)∶V(SiO2 sol)=1∶3 and treatment temperature 150℃,the transmittability of the composite coating(HT-S-EG-3C)reached up to 98.5%,~8%higher than that of the blank substrate,while the adhesion reached grade 0.Static water contact angle of 15° indicated high hydrophilicity,which led to anti-fog and anti-reflection performance.