Texture Analysis of Hydrophobic Polycarbonate and Polydimethylsiloxane Surfaces via Persistent Homology

Abstract

Due to recent climate change-triggered, regular dust storms in the Middle East, dust mitigation has become the critical issue for solar energy harvesting devices. One of the methods to minimize and prevent dust adhesion and create self-cleaning abilities is to generate hydrophobic characteristics on surfaces. The purpose of this study is to explore the topological features of hydrophobic surfaces. We use non-standard techniques from topological data analysis to extract morphological features from the AFM images. Our method recovers most of the previous qualitative observations in a robust and quantitative way. Persistence diagrams, which is a summary of topological structures, witness quantitatively that the crystallized polycarbonate (PC) surface possesses spherulites, voids, and fibrils, and the texture height and spherulite concentration increases with the increased immersion period. The approach also shows that the polydimethylsiloxane (PDMS) exactly copied the structures at the PC surface but 80 to 90 percent of the nanofibrils were not copied at PDMS surface. We next extract a feature vector from each persistence diagram to show which experiments hold features with similar variance using principal component analysis (PCA). The K-means clustering algorithm is applied to the matrix of feature vectors to support the PCA result, grouping experiments with similar features.

A Method for Simultaneous Polishing and Hydrophobization of Polycarbonate for Microfluidic Applications

“…The second important aspect of the character of the surface of PC is its wettability. The wettability of native PC surface (contact angle is 84 • ) into a hydrophobic or even superhydrophobic material is possible via physical [6][7][8][9][10][11][12][13][14][15][16] or chemical modification [17]. The physical approach uses surface texturing via controlled laser ablation [9,10,14] or via solvent induced crystallization of polycarbonate [6][7][8][11][12][13]15,16].…”

“…The wettability of native PC surface (contact angle is 84 • ) into a hydrophobic or even superhydrophobic material is possible via physical [6][7][8][9][10][11][12][13][14][15][16] or chemical modification [17]. The physical approach uses surface texturing via controlled laser ablation [9,10,14] or via solvent induced crystallization of polycarbonate [6][7][8][11][12][13]15,16]. To put it another way, a hierarchical surface structure obtained by physical modification (texturing geometry and depth) strongly increases the surface roughness [18,19].…”

“…Different types of hierarchical structures (pores, cavities and pillars) can be fabricated with the use of lasers, which consequently yields increasing the PC static contact angle from 84 • to 120 • [9,14] or even 155 • [10]. Another physical approach employs a phase separation process with the use of chemical solvents such as: dichloromethane [8], acetone [7,11,12,16], dimethylformamide [6] or a mixture of the last two [13,15]. The resulting surface texture depends on the parameters of the process such as: the type and concentration of solvent, temperature and process duration.…”

Characterization and Processing Behavior of Heated Aluminum-Polycarbonate Composite Build Plates for the FDM Additive Manufacturing Process

“…The most common type of PC is obtained by interacting diphenyl carbonate with bisphenol A (2,2-bis-(4-hydroxyphenyl)-propane) to give bisphenol-A groups linked by carbonate groups giving PC high tensile and impact strength over a wide range of temperatures. The polymers are highly transparent to visible light and have better light transmission characteristics than many types of glass and are soluble in organic solvents and alkalis [52] (p. 242) and [53].…”

Grain Analysis of Atomic Force Microscopy Images via Topological Data Analysis

“…Our method is demonstrated in two types of AFM images: (i) ZnO and Zn2O3 thin films grown by RFmagnetron sputtering [25][26]; and (ii) Polycarbonate wafers textured through crystallization in an acetone solution [24].…”