# Biocompatible Composite Protective Thin Layer Containing Cellulose Fibers and Silica Cryogel

## TL;DR

This paper describes the creation of a biocompatible composite layer using cellulose and silica cryogel for insulation and protection on various surfaces.

## Contribution

The novel contribution is the development of a composite thin layer with enhanced adhesion and reduced water solubility suitable for multiple surfaces.

## Key findings

- The composite layer's water solubility was reduced from 97 wt% to 1–3 wt% by removing alkali content.
- Surface treatments like etching and mechanical roughening significantly improved adhesion properties.
- SEM analyses showed interactions between the matrix and reinforcement phase in the composite.

## Abstract

The aim of the present research was to synthesize protective composite layers from biodegradable cellulose and biocompatible, sol–gel-derived silica cryogel. An important task in the present work was to achieve good applicability on distinct (smooth and rough) surfaces of various materials (from metallic to ceramic). The aim was to utilize the composite layers as thermal and electric insulation coating. The investigation put some effort into the enhancement of mechanical strength and the elasticity of the thin layer as well as a reduction in its water solubility. The removal of the alkali content leads successfully to a significant reduction in water solubility (97 wt% → 1–3 wt%). Adhesion properties were measured using a specialized measurement technique developed in our laboratory. Treatments of the substrate surface, such as alkaline or acidic etching (i.e., Na2CO3, HF, water glass), mechanical roughening, or the application of a thin alkali-containing primer layer, strongly increase adhesion. SEM analyses revealed the interactions between the matrix and the reinforcement phase and their morphology.