Direct measurement of electrostatic interactions between poly(methyl methacrylate) microspheres with optical laser tweezers.
basic_science · Level V
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- Record sourced from PubMed, PMID 31549697.
- Also identified by DOI 10.1039/c9sm01374a.
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Abstract
In this study, we measured the force of electrostatic interactions between poly(methyl methacrylate) (PMMA) particles dispersed in organic solvent mixtures of cyclohexyl bromide (CHB) and n-decane. Optical laser tweezers were employed to directly measure interactive forces between paired PMMA particles in a CHB medium that contained n-decane in various volume ratios. CHB, having a moderate dielectric constant, provided an environment with a high charge storage capacity. The addition of n-decane lowered the effective refractive index of the medium, which increased the optical trapping efficiency. We also fabricated microscope flow cells with a commonly used UV-curable adhesive and quantified the effects of dissolved adhesive compounds through interactive force measurements and nuclear magnetic resonance analysis. In addition, we studied the impact of CHB dissociation into H<sup>+</sup> and Br<sup>-</sup> ions, which could screen electrostatic interactions.