Preparation of highly dispersed and concentrated aqueous suspensions of nanodiamonds using novel diblock dispersants

Ren-Mian Chin; Shinn-Jen Chang; Chia-Chen Li; Cha-Wen Chang; Ruo-Han Yu

doi:10.1016/j.jcis.2018.03.017

Preparation of highly dispersed and concentrated aqueous suspensions of nanodiamonds using novel diblock dispersants

J Colloid Interface Sci. 2018 Jun 15:520:119-126. doi: 10.1016/j.jcis.2018.03.017. Epub 2018 Mar 7.

Authors

Ren-Mian Chin¹, Shinn-Jen Chang², Chia-Chen Li³, Cha-Wen Chang², Ruo-Han Yu²

Affiliations

¹ Institute of Materials Science and Engineering, and Department of Materials & Mineral Resources Engineering, National Taipei University of Technology, Taipei 10608, Taiwan.
² Material and Chemical Research Laboratories, Industrial Technology Research Institute, Hsinchu 30011, Taiwan.
³ Institute of Materials Science and Engineering, and Department of Materials & Mineral Resources Engineering, National Taipei University of Technology, Taipei 10608, Taiwan. Electronic address: ccli@ntut.edu.tw.

PMID: 29533851
DOI: 10.1016/j.jcis.2018.03.017

Abstract

Hypothesis: Finding an efficient dispersant for obtaining a good dispersion of 5-nm detonation nanodiamond (DND) is always a challenge. Two newly designed diblock copolymers, both poly(ammonium methacrylate)-block-poly(2-phenoxyethyl acrylate) (PMA-b-PBEA) but with different molar ratios of PMA to PBEA, were proposed to be efficient dispersants in stabilizing the concentrated aqueous suspensions of DND.

Experiments: The dispersion efficiency of dispersants for DND in aqueous suspensions was studied by the measurements of particle size, sedimentation property, and rheological behavior. The interactions between the added dispersants and DND were identified by the zeta potential and adsorption analyses. Calculations based on Derjaguin-Landau-Verwey-Overbeek (DLVO) theory were conducted for clarifying the dominant parameters relating to the dispersion efficiency of dispersants.

Findings: Compared with the commercially popular dispersant ammonium polyacrylate, these two diblock dispersants exhibited superior efficiency in the stabilization of DND suspensions. Using the diblock copolymers as dispersants, good dispersion stability in a DND suspension with an extremely high solid content of 30 wt% was achieved. According to experimental analyses and based on DLVO calculations, a low number of accompanied counter-ions, high adsorption capability, and thick PMA-b-PBEA adsorption layer are the main reasons for the extremely high dispersion efficiency of the two new dispersants.

Keywords: Adsorption; Aqueous suspension; DLVO theory; Detonation nanodiamond; Dispersion; Polyacrylate.