Robust Silica-Cellulose Composite Aerogels with a Nanoscale Interpenetrating Network Structure Prepared Using a Streamlined Process.

Huazheng Sai,Litong Ma,Jing Zhang,Zhiqiang Jin,Yaxiong Wang,Rui Fu,Yutong Wang,Meijuan Wang

doi:10.3390/polym12040807

Huazheng Sai, Litong Ma + Show 6 more

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https://doi.org/10.3390/polym12040807

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Journal: Polymers	Publication Date: Apr 3, 2020
Citations: 9	License type: CC BY 4.0

Affiliation: Inner Mongolia University of Science and Technology

Abstract

Silica aerogels can be strengthened by forming a nanoscale interpenetrating network (IPN) comprising a silica gel skeleton and a cellulose nanofiber network. Previous studies have demonstrated the effectiveness of this method for improving the mechanical properties and drying of aerogels. However, the preparation process is generally tedious and time-consuming. This study aims to streamline the preparation process of these composite aerogels. Silica alcosols were directly diffused into cellulose wet gels with loose, web-like microstructures, and an IPN structure was gradually formed by regulating the gelation rate. Supercritical CO2 drying followed to obtain composite aerogels. The mechanical properties were further enhanced by a simple secondary regulation process that increased the quantity of bacterial cellulose (BC) nanofibers per unit volume of the matrix. This led to the production of aerogels with excellent bendability and a high tensile strength. A maximum breaking stress and tensile modulus of 3.06 MPa and 46.07 MPa, respectively, were achieved. This method can be implemented to produce robust and bendable silica-based composite aerogels (CAs).

Highlights

Aerogels are synthetic materials characterized by fine internal void spaces, open-pore geometry, and useful properties including low density, high porosity, high specific surface, and low thermal conductivity [1,2,3]
The weight of the dried samples first increased rapidly, and the growth rate became gentle and stabilized within 120 min (Figure 2a). This indicates that without condensation in the alcosols, the silica nanoparticles and precursor could diffuse in the bacterial cellulose (BC) matrix effectively; a diffusion balance was reached within 2 h
The pores in the BC matrix are much larger and more uniform than the nanoscale pore size of the cellulose nanofibers networks that were used as the matrix in previous studies [44,45,47]

Summary

Introduction

Aerogels are synthetic materials characterized by fine internal void spaces, open-pore geometry, and useful properties including low density, high porosity, high specific surface, and low thermal conductivity [1,2,3]. These materials have broad application potential in thermal insulation [4,5], oil absorption [6], catalysis [7], electrode materials [8], CO2 remove [9], tissue engineering [10], energy storage [11], adsorption of heavy metal ions [12], and as drug carriers [13]. The weak mechanical strength of aerogels means that they must be carefully manufactured, and these tedious and time-consuming preparation processes are often costly [16].

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