SiO_2膜的孔径调节及疏水改性

Pore diameter adjusting and hydrophobic modification of SiO_2 film

以正硅酸乙酯为前驱体,添加聚丙烯酸[1](PAA)来增大SiO_2膜的孔径,并用聚合物溶液沉淀相转化法[2-3]对其进行疏水改性。通过热重分析(TG-DTG)、红外光谱(IR)、X射线衍射(XRD)、原子力显微镜(AFM)、比表面积(BET)以及接触角测量等对试样的热稳定性、化学组成、物相组成、比表面积及孔径分布、表面形貌和疏水性能等进行分析。结果表明,当PAA加入量为10%(体积分数,下同),800℃烧成后膜孔径可达53.73 nm。随PAA加入量增多,SiO_2膜孔径增大,但当加入量达到15%,800℃下焙烧时,膜表面开始出现裂纹;疏水改性后SiO_2膜的接触角的可增大至113°,但改性后的SiO_2膜孔洞明显较小,原因是涂覆于膜面的二甲基二乙氧化硅(DDS)堵塞了孔洞。可以得出在PAA加入量为10%~15%之间,600℃焙烧时,SiO_2膜可获得良好的疏水性。

Using ethyl orthosilicate as precursors,the pore size of the SiO2 membrane was increased by adding PAA,and the hydrophobicity was modified by the method of polymer solution precipitation phase transformation.The thermal stability,chemical composition,phase composition,specific surface area and pore size distribution,surface morphologies and hydrophobicity of the samples were analyzed by the method of TG-DTG,IR,XRD,AFM,BET and contact angle measurements.The results show that the optimum PAA adding amount is 10%(volume ratio),and the pore size is up to 53.73 nm after sintering at 800℃.With increasing the PAA adding amount,the pore size of SiO2 membrane increases,but when the adding amount reaches 15%(volume fraction),sintering at 800℃,the membrane surface begins to appear crack.The contact angle of the SiO2 membrane after hydrophobicity modification can increase to 113°.The pore size of the modified SiO2 membrane is obviously smaller after hydrophobically modified,it is because that the DDS coating on the membrane surface blocks the pore.It can be concluded that when the PAA is added in an amount between 10%and 15%and the sintering temperature is 600℃,the membrane with good hydrophobicity can be obtained.