Shear Bond Strength to Enamel, Mechanical Properties and Cellular Studies of Fiber-Reinforced Composites Modified by Depositing SiO₂ Nanofilms on Quartz Fibers via Atomic Layer Deposition

Abstract

Introduction

Poor interfacial bonding between the fibers and resin matrix in fiber-reinforced composites (FRCs) is a significant drawback of the composites. To enhance the mechanical properties of FRC, fibers were modified by depositing SiO₂ nanofilms via the atomic layer deposition (ALD) technique. This study aims to evaluate the effect of ALD treatment of the fibers on the mechanical properties of the FRCs.

Methods

The quartz fibers were modified by depositing different cycles (50, 100, 200, and 400) of SiO₂ nanofilms via the ALD technique and FRCs were proposed from the modified fibers. The morphologies, surface characterizations of nanofilms, mechanical properties, and cytocompatibility of FRCs were systematically investigated. Moreover, the shear bond strength (SBS) of FRCs to human enamel was also evaluated.

Results

The SEM and SE results showed that the ALD-deposited SiO₂ nanofilms have good conformality and homogeneity. According to the results of FTIR and TGA, SiO₂ nanofilms and quartz fiber surfaces had good chemical combinations. Three-point bending tests with FRCs showed that the deposited SiO₂ nanofilms effectively improved FRCs’ strength and Group D underwent 100 deposition cycles and had the highest flexural strength before and after aging. Furthermore, the strength of the FRCs demonstrated a crescendo-decrescendo tendency with SiO₂ nanofilm thickness increasing. The SBS results also showed that Group D had outstanding performance. Moreover, the results of cytotoxicity experiments such as cck8, LDH and Elisa, etc., showed that the FRCs have good cytocompatibility.

Conclusion

Changing the number of ALD reaction cycles affects the mechanical properties of FRCs, which may be related to the stress relaxation and fracture between SiO₂ nanofilm layers and the built-up internal stresses in the nanofilms. Eventually, the SiO₂ nanofilms could enhance the FRCs’ mechanical properties and performance to enamel by improving the interfacial bonding strength, and have good cytocompatibility.

Graphical Abstract

Keywords:

• atomic layer deposition
• SiO₂ nanofilms
• surface modification
• interfacial bonding

Ethics Approval and Informed Consent

Informed consents were signed with the approval of the Ethics Committee of the Affiliated Hospital of Stomatology, Nanjing Medical University (permit number: PJ2023-074-001). All research studies have been performed in accordance with the principles stated in the Declaration of Helsinki.

Acknowledgments

This work was supported by Jiangsu Province Capability Improvement Project through Science, Technology and Education-Jiangsu Provincial Research Hospital Cultivation Unit (YJXYYJSDW4), Jiangsu Provincial Medical Innovation Center (CXZX202227) and the National Natural Science Foundation of China [grant number 81701025].

Disclosure

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.