Composite Material of PDMS with Interchangeable Transmittance: Study of Optical, Mechanical Properties and Wettability

Flaminio Sales,João Ribeiro,Andrews Souza,Rui Lima,Elder Giovanetti,Ronaldo Ariati,Verônica Noronha

doi:10.3390/jcs5040110

Flaminio Sales, João Ribeiro + Show 5 more

Open Access

https://doi.org/10.3390/jcs5040110

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Abstract

Polydimethylsiloxane (PDMS) is a polymer that has attracted the attention of researchers due to its unique properties such as transparency, biocompatibility, high flexibility, and physical and chemical stability. In addition, PDMS modification and combination with other materials can expand its range of applications. For instance, the ability to perform superhydrophobic coating allows for the manufacture of lenses. However, many of these processes are complex and expensive. One of the most promising modifications, which consists of the development of an interchangeable coating, capable of changing its optical characteristics according to some stimuli, has been underexplored. Thus, we report an experimental study of the mechanical and optical properties and wettability of pure PDMS and of two PDMS composites with the addition of 1% paraffin or beeswax using a gravity casting process. The composites’ tensile strength and hardness were lower when compared with pure PDMS. However, the contact angle was increased, reaching the highest values when using the paraffin additive. Additionally, these composites have shown interesting results for the spectrophotometry tests, i.e., the material changed its optical characteristics when heated, going from opaque at room temperature to transparent, with transmittance around 75%, at 70 °C. As a result, these materials have great potential for use in smart devices, such as sensors, due to its ability to change its transparency at high temperatures.

Highlights

Nowadays, polymers and elastomers have been attracting the attention of many researchers with its performance in the daily and environmental life of the planet due to their wide range of chemical and physical properties and excellent characteristics such as flexibility and corrosion resistance [1]
There is an increasing interest in the study of polydimethylsiloxane (PDMS) for applications such as mechanical and civil engineering, electronic devices, and in biomedical fields [2,3,4,5,6,7]. Applications were reported such as water/oil and gas filtration membranes [8,9,10], sensors [11,12,13], lubricants [14], sealing agents [15], blood analogues [16,17,18], and for microfluidic devices [19,20,21,22,23]
There has been a significant growing interest in microelectromechanical systems (MEMS) and microfluidic and optical devices [24]. This wide range of applications is justified by the desirable properties presented by this polymer, PDMS, a silicone based on organic polymers that is non-toxic, non-flammable, and known as a material for which processing is simple with good repeatability and low cost

Summary

Introduction

Polymers and elastomers have been attracting the attention of many researchers with its performance in the daily and environmental life of the planet due to their wide range of chemical and physical properties and excellent characteristics such as flexibility and corrosion resistance [1]. There has been a significant growing interest in microelectromechanical systems (MEMS) and microfluidic and optical devices [24] This wide range of applications is justified by the desirable properties presented by this polymer, PDMS, a silicone based on organic polymers that is non-toxic, non-flammable, and known as a material for which processing is simple with good repeatability and low cost. It is an optically transparent material [11,25], biocompatible [26,27,28], highly flexible [29,30], waterproof [31], viscoelastic, and chemically and thermally stable [32,33,34]

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