Flexible Nanocomposites Based on Polydimethylsiloxane Matrices with DNA-Modified Graphene Filler: Curing Behavior by Differential Scanning Calorimetry.

Elisa Toto,Susanna Laurenzi,Maria Gabriella Santonicola

doi:10.3390/polym12102301

Abstract

Novel silicone-based nanocomposites with varied elastic properties were prepared by blending standard polydimethylsiloxane (PDMS) with a lower viscosity component (hydroxyl-terminated PDMS) and integrating a graphene nanoplatelets (GNP) filler modified by strands of deoxyribonucleic acid (DNA). The curing behavior of these nanocomposites was studied by dynamic and isothermal differential scanning calorimetry. The activation energies of the polymerization reactions were determined using the Kissinger method and two model-free isoconversional approaches, the Ozawa–Flynn–Wall and the Kissinger–Akahira–Sunose methods. Results show that the complex trend of the curing behavior can be described using the isoconversional methods, unveiling lower activation energies for the nanocomposites with standard PDMS matrices. The role of the DNA modification of graphene on the curing behavior is also demonstrated. The curing reactions of the nanocomposites with the PDMS matrix are favored by the presence of the GNP–DNA filler. PDMS/PDMS–OH blends generate softer nanocomposites with hardness and reduced elastic modulus that can be tuned by varying the amount of the filler.

Highlights

Composite materials consisting of carbon-based fillers embedded in an elastomeric polymer matrix are increasingly considered for stretchable and flexible electrodes in applications such as sensors, transducers and actuators in different fields, from aerospace technology to biomedicine and biotechnology [1,2,3]
The interest in silicone nanocomposites with graphene filler is steadily growing as they can be endowed with a wide array of multifunctional properties by integrating the exceptional mechanical strength and the good thermal and electrical conductivities of graphene nanoplatelets (GNP) [4,5,6] with the flexibility of a nontoxic polymer matrix, such as polydimethylsiloxane (PDMS), which is widely used in biocompatible materials and wearable devices [7,8]
Dynamic differential scanning calorimetry was used to analyze the curing kinetics of nanocomposite mixtures made of silicone-based matrices containing GNP nanofiller modified with

Summary

Introduction

Composite materials consisting of carbon-based fillers embedded in an elastomeric polymer matrix are increasingly considered for stretchable and flexible electrodes in applications such as sensors, transducers and actuators in different fields, from aerospace technology to biomedicine and biotechnology [1,2,3]. The interest in silicone nanocomposites with graphene filler is steadily growing as they can be endowed with a wide array of multifunctional properties by integrating the exceptional mechanical strength and the good thermal and electrical conductivities of graphene nanoplatelets (GNP) [4,5,6] with the flexibility of a nontoxic polymer matrix, such as polydimethylsiloxane (PDMS), which is widely used in biocompatible materials and wearable devices [7,8]. The DNA-modified graphene nanofiller was successfully embedded in a silicone (Sylgard 184 PDMS) matrix, which is transparent to UV radiation, creating a UV-sensitive stretchable nanocomposite [13]. This would allow for the use of such nanocomposites as soft elastic substrates for cell proliferation [16]

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Conclusion