Facile Preparation of Hydrophobic PET Surfaces by Solvent Induced Crystallization

Elisabet Afonso,Aránzazu Martínez-Gómez,Nuria García,Andrea Huerta,Pilar Tiemblo

doi:10.3390/coatings12020137

Elisabet Afonso, Aránzazu Martínez-Gómez + Show 3 more

Open Access

https://doi.org/10.3390/coatings12020137

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Abstract

In this work, Polyethylene terephthalate (PET), one of the most widely consumed polymers, has been used as starting material for the development of non-stick surfaces through a fast, simple and scalable method based on solvent-induced crystallization to generate roughness, followed by a fluorination step. Several solvents were tested, among which dichloromethane was chosen because it gives rise to the formation of a particulate layer with rough topography. This particulate layer was covered by a polymer thin and smooth skin that must be removed to leave the rough layer as surface. The skin has been successfully removed by two strategies based on mechanical and chemical removal, each strategy producing different surface properties. A final treatment with a diluted solution of a fluorinated silane showed that it is possible to obtain PET surfaces with a water contact angle higher than 150° and low water adhesion. The reason behind this behavior is the development of a hierarchical rough profile during the induced polymer crystallization process. These surfaces were characterized by XRD, FTIR and DSC to monitor solvent induced crystallization. Topography was studied by SEM and optical profilometry. Wetting behavior was studied by measuring the contact angles and hysteresis.

Highlights

Surface modification of polymer materials is an appealing strategy to manage desirable functionalities, such as water repellency, antiicing, antifogging, antifouling, anticorrosion, and friction reduction, among others [1,2,3,4,5,6]
In this work, Polyethylene terephthalate (PET), one of the most widely consumed polymers, has been used as starting material for the development of non-stick surfaces through a fast, simple and scalable method based on solvent-induced crystallization to generate roughness, followed by a fluorination step
This particulate layer was covered by a polymer thin and smooth skin that must be removed to leave the rough layer as surface

Summary

Introduction

Surface modification of polymer materials is an appealing strategy to manage desirable functionalities, such as water repellency, antiicing, antifogging, antifouling, anticorrosion, and friction reduction, among others [1,2,3,4,5,6]. Several approaches based on bottom-up and top-down methods have been used to develop rough surfaces, whereas chemical modification is commonly done by fluorination and plasma treatments. The most widely known lotus leaf profile to achieve hydrophobicity is based on hierarchical rough structures on the micrometric and nanometric scales. In this sense, one of the most popular strategies is the application of particle coatings, modified silica nanoparticles or all-organic particles [7]. Choosing starting materials highly available such as polymers makes sense because of the versatility of these materials in terms of properties, and because the development of non-stick properties in polymeric surfaces fosters the adaptation of these materials to the circular economy objectives. Controlling wetting properties helps optimizing the use of resources and simplifies the rinsing stage previous to recycling by making surfaces self-cleaning

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