Effects of the Nanomechanical Properties of Polymer Nanoparticles on Crack Patterns during Drying of Colloidal Suspensions

Abstract

Coalescence during drying of suspensions containing glassy polymer nanoparticles generates fascinating crack patterns, whereas coalescence of soft polymer particles gives crack-free films. This process is widely used in environmental-friendly water-based coatings, which use nanosized polymer nanoparticles in the film formation process. Numerous studies have shown that polymer nanoconfinement could lead to a drastic modification of the polymer properties such as a reduction of the glass transition temperature (T g). If such a change in the properties of polymers also exists when nanoconfined in nanoparticles in suspension, then one would expect an alteration in the film formation process, particularly a reduction in the minimum film formation temperature. In this paper we look at the effect of nanomechanical properties of polymer nanoparticles on crack patterns generated by particle coalescence. We study crack pattern morphology during drying of aqueous suspensions of PBMA nanoparticles (50 nm diameter) with different nanomechanical properties (different cross-linking ratios). We investigate the effect of temperature and relaxation time on crack morphologies in the transition from crack to crack-free films. These results were analyzed in terms of time−temperature superposition and compared to bulk behavior.

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Film‐forming behavior and mechanical properties of colloidal silica/polymer latex blends with high silica load

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