Quantitative imaging of heterogeneous dynamics in drying and aging paints

Abstract

Drying and aging paint dispersions display a wealth of complex phenomena that make their study fascinating yet challenging. To meet the growing demand for sustainable, high-quality paints, it is essential to unravel the microscopic mechanisms underlying these phenomena. Visualising the governing dynamics is, however, intrinsically difficult because the dynamics are typically heterogeneous and span a wide range of time scales. Moreover, the high turbidity of paints precludes conventional imaging techniques from reaching deep inside the paint. To address these challenges, we apply a scattering technique, Laser Speckle Imaging, as a versatile and quantitative tool to elucidate the internal dynamics, with microscopic resolution and spanning seven decades of time. We present a toolbox of data analysis and image processing methods that allows a tailored investigation of virtually any turbid dispersion, regardless of the geometry and substrate. Using these tools we watch a variety of paints dry and age with unprecedented detail.

Imaging the Molecular Motions of Autonomous Repair in a Self‐Healing Polymer

“…Laser Speckle Imaging : The LSI method is based on the multiple scattering of light, essentially the imaging equivalent of Ddffusive Wwve Ssectroscopy . See van der Kooij et al for a detailed description of the technique. In this experimental LSI setup (Figure S3, Supporting Information), an expanded and coherent laser beam (Cobolt Samba, 1 W, λ = 532 nm) was projected onto the turbid sample of interest.…”

“…In this paper, we visualize for the first time the microscale dynamics governing the macroscopic repair of a polymer using the optical method laser speckle imaging (LSI) . We study autonomous healing in a thermoplastic, polyetherimide‐based elastomer that exhibits excellent mechanical properties and spontaneous healing under ambient conditions .…”

A critical and quantitative review of the stratification of particles during the drying of colloidal films

“…95 It is a good candidate technique to characterize structure formation during the stratification process. Laser speckle imaging 96 has been demonstrated to provide information on heterogeneous particle dynamics in drying colloid films and paints with a spatial resolution of micrometres and a time resolution of milliseconds. In the future, it could be employed as a powerful complementary technique in the study of stratifying systems.…”

Laser Speckle Strain Imaging reveals the origin of delayed fracture in a soft solid

“…We quantify the internal dynamics in the elastomer during the mechanical experiment in space and time by analyzing the fluctuations of the speckle pattern created by multiply scattered photons ( Fig. 1 , B and C, and movie S1), using the intensity structure function to create image contrast ( 17 , 21 , 24 , 25 ) where I is the speckle intensity at position ( x , y ) and at time to macroscopic fracture Δ t = t − t f , and τ is the correlation time. Whereas the raw speckle images of a strained elastomer show no signs of precursors to failure ( Fig.…”