Graphene Based Poly(Vinyl Alcohol) Nanocomposites Prepared by In Situ Green Reduction of Graphene Oxide by Ascorbic Acid: Influence of Graphene Content and Glycerol Plasticizer on Properties.

Mónica Cobos,M Fernández

doi:10.3390/nano8121013

Abstract

The enhanced properties of polymer nanocomposites as compared with pure polymers are only achieved in the presence of well-dispersed nanofillers and strong interfacial adhesion. In this study, we report the preparation of nanocomposite films based on poly(vinyl alcohol) (PVA) filled with well dispersed graphene sheets (GS) by in situ reduction of graphene oxide (GO) dispersed in PVA solution using ascorbic acid (L-AA) as environmentally friendly reductant. The combined effect of GS content and glycerol as plasticizer on the structure, thermal, mechanical, water absorption, and water barrier properties of PVA/GS nanocomposite films is studied for the first time. Higher glass transition temperature, lower crystallinity, melting, and crystallization temperature, higher mechanical properties, and remarkable improvement in the thermal stability compared to neat PVA are obtained as a result of strong interfacial interactions between GS and PVA by hydrogen bonding. PVA/GS composite film prepared by ex situ process is more brittle than its in situ prepared counterpart. The presence of GS improves the water barrier and water resistance properties of nanocomposite films by decreasing water vapor permeability and water absorption of PVA. This work demonstrates that the tailoring of PVA/GS nanocomposite properties is enabled by controlling GS and glycerol content. The new developed materials, particularly those containing plasticizer, could be potential carriers for transdermal drug delivery.

Highlights

Poly(vinyl alcohol) (PVA) is a water-soluble semi-crystalline synthetic polymer obtained from the precursor polymer poly(vinyl acetate)
We report the preparation of nanocomposite films based on poly(vinyl alcohol) (PVA) filled with well dispersed graphene sheets (GS) by in situ reduction of graphene oxide (GO) dispersed in PVA solution using ascorbic acid (L-AA) as environmentally friendly reductant
The in situ reduction of GO in the presence of PVA by L-AA strategy adopted in this work to obtain PVA/Graphene Sheets Nanocomposite Films (PVA/GS) nanocomposites resulted in a good dispersion state of GS in the polymer matrix due to interactions through hydrogen bonding

Summary

Introduction

Poly(vinyl alcohol) (PVA) is a water-soluble semi-crystalline synthetic polymer obtained from the precursor polymer poly(vinyl acetate). In this study we show a simple, efficient and environment-friendly method to prepare PVA/graphene nanocomposites by in situ reduction of GO dispersed in PVA water solution, using ascorbic acid as the reducing reagent. A comparative study of an analogous PVA/graphene nanocomposite film prepared by Nanomaterials 2018, 8, 1013 the ex situ method is reported This green method has several advantages: its environmental friendliness, the most abundant and smallest graphitic domains produced by ascorbic acid as compared to other environment-friendly reductants [48,49], the suitability of the ascorbic acid reduced GO for biomedical applications, since both the L-AA and the resulting oxidized products are eco-friendly, and the prevention of graphene agglomeration in the PVA matrix. We have demonstrated that, by controlling the nanofiller and glycerol plasticizer content, the properties of PVA/GS nanocomposites may be tailored

Materials

Characterization Techniques

Findings

Conclusions