Particle dispersion governs nano to bulk dynamics for tailored nanocomposite design

Colijn, Ivanna; Postma, Erik; Fix, Raoul; van der Kooij, Hanne M.; Schroën, Karin

doi:10.1016/j.jcis.2023.12.071

Cited by 2 publications

(1 citation statement)

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“…LSI exploits multiple light scattering to evaluate, with both high temporal and spatial resolution, the dynamics inside opaque materials. This characteristic feature has encouraged the deployment of LSI in numerous fields such as biology, food technology, materials science, and surface science. − In a turbid medium, light propagates via multiple scattering events. After a certain number of such events, the propagation direction of the photons is completely randomized (Figure a, inset).…”

Section: Resultsmentioning

confidence: 99%

Quantifying the Open Time and Film Formation of Waterborne Coatings with Laser Speckle Imaging

Semerdzhiev,

van der Kooij,

Fokkink

et al. 2024

ACS Appl. Opt. Mater.

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In drying waterborne paints, the time span between the deposition of the liquid dispersion and the formation of a uniform solid film harbors a procession of complex phenomena each of which determines the final properties of the dry paint film. One of the major challenges in the design of sustainable, water-based paints is to match or surpass the drying performance of their solvent-based counterparts. In particular, the so-called “open time”the time during which the paint remains wet and susceptible to alterations without affecting the aesthetics of the final filmis often much shorter in waterborne systems than in solvent-borne equivalents. This short time window hastens the painter, limits remodeling of defects, and makes it difficult to smoothly blend the edges of a previously and freshly deposited paint without introducing permanent brush marks. Optimizing and tailoring the open time is thus desired. This endeavor would greatly benefit from methods capable of determining this critical parameter in a fast and objective way. Yet, experimental access to the internal dynamics accompanying the drying process is challenging. Paints are often opaque, which precludes the use of traditional optical methods. Additionally, the drying phenomena usually populate a multitude of time and length scales. To address these obstacles, we deploy the optical technique laser speckle imaging (LSI), which allows probing nanoscale motions deep inside turbid paints. We apply this method to quantitatively and objectively determine the open time. We develop a set of scaling relations that accurately predict the experimentally measured open time as a function of key parameters governing the drying process. Additionally, we harness the wide temporal dynamic range of LSI to capture phenomena that occur during the later drying stages, including deformation and coalescence of the polymer particles.

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