Polysiloxane Bonded Silica Aerogel with Enhanced Thermal Insulation and Strength.

Weilin Wang,Zongwei Tong,Huiming Ji,Dong Su,Ran Li

doi:10.3390/ma14082046

Abstract

In order to improve the mechanical properties of SiO2 aerogels, PHMS/VTES-SiO2 composite aerogels (P/V-SiO2) were prepared. Using vinyltriethoxysilane (VTES) as a coupling agent, the PHMS/VTES complex was prepared by conducting an addition reaction with polyhydromethylsiloxane (PHMS) and VTES and then reacting it with inorganic silica sol to prepare the organic–inorganic composite aerogels. The PHMS/VTES complex forms a coating structure on the aerogel particles, enhancing the network structure of the composite aerogels. The composite aerogels can maintain the high specific surface area and excellent thermal insulation properties, and they have better mechanical properties. We studied the reaction mechanism during preparation and discussed the effects of the organic components on the structure and properties of the composite aerogels. The composite aerogels we prepared have a thermal conductivity of 0.03773 W·m−1·K−1 at room temperature and a compressive strength of 1.87 MPa. The compressive strength is several times greater than that of inorganic SiO2 aerogels. The organic–inorganic composite aerogels have excellent comprehensive properties, which helps to expand the application fields of silicon-based aerogels.

Highlights

SiO2 aerogels have many advantages, including low thermal conductivity, low density and large specific surface area [1,2,3]. They can be used for thermal insulation [4,5], oil-water separation [6], wastewater treatment [7], sound insulation [8] and catalysts [9]
The preparation of the composite aerogels can be divided into three stages: (1) The organic polymer (PHMS) and coupling agent (VTES) formed the PHMS/VTES complex by an addition reaction
(2) The PHMS/VTES complex reacted with silica sol to form composite gels

Summary

Introduction

SiO2 aerogels have many advantages, including low thermal conductivity, low density and large specific surface area [1,2,3]. They can be used for thermal insulation [4,5], oil-water separation [6], wastewater treatment [7], sound insulation [8] and catalysts [9]. SiO2 aerogels prepared by ambient pressure drying is generally less than 0.6 MPa [10,11]. In order to enhance the mechanical properties of SiO2 aerogels, the following methods have been proposed: changing precursor [13,14], organic polymer reinforcement [7,15] and fiber reinforcement [16,17]. We focused on two methods: changing precursor and organic polymer reinforcement

Methods

Results

Discussion

Conclusion