The effect of temperature on the ordered thin film of silica nanoparticles was studied by LB-BAM combination technique
利用LB-BAM联用技术研究温度对二氧化硅纳米颗粒有序薄膜的影响

摘要

本文采用Langmuir-Blodgett（LB）技术与Brewster Angle Microscopy（BAM）技术联用，系统研究了温度对空气-水界面上二氧化硅纳米颗粒有序薄膜形成的影响。实验结果表明，在10-20℃条件下，二氧化硅单层膜的等温曲线变化较小，薄膜在较大表面压力范围内保持固相，且纳米颗粒排列紧密有序。当温度高于25℃时，等温曲线发生显著变化，气相向液相转变过程减缓，纳米颗粒堆积行为受到影响。在25℃条件下，表面压力为36和40mN/m时，单层膜较为平坦，而在较低压力下出现亮区和暗区，表明液相扩张相与凝聚相共存。温度升高至45℃时，单层膜出现相分离和纳米颗粒团聚现象，均匀性显著降低。研究证实，压缩速率为7mm/min时,温度控制在20℃以下，有利于形成均匀且有序的二氧化硅纳米颗粒薄膜。本研究为优化LB技术制备工艺提供了重要指导，对探索温度调控下的新型有序薄膜结构及其应用具有参考意义。

Abstract

In this paper, Langmuir-Blodgett (LB) technique was combined with Brewster Angle Microscopy (BAM) technique to systematically study the effect of temperature on the formation of ordered thin films of silica nanoparticles at the air-water interface. The experimental results show that under the condition of 10-20℃, the isothermal curve of silica monolayer film changes little, the film remains solid in a large surface pressure range, and the nanoparticles are arranged tightly and orderly. When the temperature is higher than 25℃, the isothermal curve changes significantly, the transition process from gas phase to liquid phase slows down, and the stacking behavior of nanoparticles is affected. Under the condition of 25℃, when the surface pressure is 36 and 40mN/m, the monolayer film is relatively flat, while bright and dark areas appear at lower pressures, indicating that the liquid expansion phase and the condensed phase coexist. When the temperature rises to 45°C, phase separation and nanoparticle agglomeration occur in the monolayer film, and the uniformity is significantly reduced. Studies have shown that when the compression rate is 7 mm/min and the temperature is controlled below 20°C, it is conducive to the formation of a uniform and ordered silica nanoparticle film. This study provides important guidance for optimizing the LB technology preparation process and has reference significance for exploring new ordered film structures and their applications under temperature control.