Anisotropic robustness of talc particles after surface modifications probed by atomic force microscopy force spectroscopy--颗粒学报PARTICUOLOGY

Dokmai, V., Sinthiptharakoon, K., Phuthong, W., & Pavarajarn, V. (2021). Anisotropic robustness of talc particles after surface modifications probed by atomic force microscopy force spectroscopy. Particuology, 58, 308-315. https://doi.org/10.1016/j.partic.2021.04.008

Anisotropic robustness of talc particles after surface modifications probed by atomic force microscopy force spectroscopy

Vipada Dokmai ^a, Kitiphat Sinthiptharakoon ^b, Witchukorn Phuthong ^c *, Varong Pavarajarn ^a *

a Center of Excellence in Particle and Materials Processing Technology, Department of Chemical Engineering, Faculty of Engineering, Chulalongkorn University, Bangkok 10330, Thailand
b National Nanotechnology Center (NANOTEC), National Science and Technology Development Agency (NSTDA), 111 Thailand Science Park, Phahonyothin Road, Khlong Nueng, Khlong Luang, Phathum Thani 12120, Thailand
c Department of Physics, Faculty of Science, Kasetsart University, Ladyao, Chatuchak, Bangkok 10900, Thailand

10.1016/j.partic.2021.04.008

Volume 58, October 2021, Pages 308-315

Received 21 January 2021, Revised 20 March 2021, Accepted 10 April 2021, Available online 8 May 2021, Version of Record 13 September 2021.

E-mail: witchukorn.ph@ku.ac.th; Varong.P@chula.ac.th

Highlights

• From AFM measurement, adhesion of talc was found to result from van der Waals interactions.

• Anisotropic characters of talc surfaces persist even after surface modifications.

• Difference in hydrophobicity of different talc surfaces was experimentally verified.

Abstract

As a versatile mineral, the crystalline hydrated magnesium silicate talcum, or talc, has been widely used in numerous industries from pharmaceutical formulations to composite material designs. Its efficient application as filler/additives incorporates the improvement in concomitant properties within materials, e.g., strength, which involves interactions between talc particles and aqueous/nonaqueous matrices. Successful property enhancement imposes ideal mixing and homogenous adhesion within a talc particle, but they are limited by the coexistence of face and edge surfaces of talc, which exhibit different level of hydrophobicity. Here, using atomic force microscopy force spectroscopy, we showed that although hydrophilic talc particles obtained from acid treatment or aminosilanization better adhered with materials representing a matrix, the anisotropic characters of the two surface types persisted. Conversely, the degree of talc’s surface anisotropy reduced with the surface hydrophobization by aliphatic methylsilanization, but followed by the decrease in adhesion. With ten-fold difference in Hamaker constants of the probe/talc surface interacting pairs, we showed that the adhesions resulted from van der Waals interactions that suggested the influence of surface polarity. The insight from this work would provide grounds for strategies to modulate talc’s adhesion, hydrophobicity and surface uniformity.

Graphical abstract

Keywords

Talc; Atomic force microscopy; Force spectroscopy; AdhesionSurface

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