Multilayer composite microcapsules synthesized by Pickering emulsion templates and their application in self-healing coating

Abstract

ARTICLE This journal isMultilayer composite microcapsules, richly and efficiently loaded with healing reagents (Isophorone diisocyanate, IPDI), are prepared based on lignin nanoparticle-stabilized oil-in-water (O/W) Pickering emulsion templates. The size control of the microcapsules is conducted by varying the lignin content and oil-water volume ratio in Pickering emulsions. With scanning electron microscope (SEM) and optical microscope (OM), the resulting microcapsules show spherical shape, ideal structure of rough outer surface and smooth inner surface, shell thickness of 4.5 m and mean diameter of 40-117 m. Fourier transform infrared spectra (FTIR) and Thermal gravimetric analysis (TGA) indicate extraordinary characteristics of the capsules: core fractions of 81.1 wt.%, excellent thermal stability with initial evaporating temperature of IPDI elevated for 72 °C, firm durability among aqueous solution-submersion and air-exposure with mass loss about 9.7 wt.% after four days submersion or two weeks exposure. Furthermore, the microcapsules are embedded into epoxy coatings for applying this technology into anticorrosive polymer coatings. Investigated by brine-submersion corrosion-accelerating test, the selfhealing microcapsules-incorporated epoxy coatings on steel plates demonstrate good dispersibility of capsules in coatings and favourable anticorrosive effects.

A simple process for lignin nanoparticle preparation

“…Successful utilization of lignin nanoparticles to reinforce phenolic foams or to stabilize Pickering emulsions has been reported in the literature. [9][10][11] Furthermore, as water dispersed polymer nanoparticles have been widely investigated in drug delivery systems, 12 lignin nanoparticles could be a potential precursor for drug delivery applications.…”

‘Containers’ for self-healing epoxy composites and coating: Trends and advances

“…Grubbs catalyst embedded in the matrix initiated the polymerization of the released DCPD via ring-opening metathesis polymerization (ROMP) Figure 2. Schematic for the synthesis process of multilayer composite microcapsules loaded with healing agents based on Pickering emulsion templates [29] Figure 3. Schematic illustration of the general route towards fabrication of healing agent-filled nanocapsules from miniemulsions using pre-synthesized polymers [31] to rebond the crack plane at room temperature.…”

“…Successively, the solvent evaporation technique was employed to form a PMMA shell around the polyetheramine core. Very recently, a facile method of preparation of microcapsules based on Pickering emulsion, in which the solid particles adsorbed on oil-water interface instead of surfactants in traditional emulsion was introduced [28,29]. Soild particles like nanoclay and lignin are remarkably stable to protect droplets from aggregation.…”

“…Soild particles like nanoclay and lignin are remarkably stable to protect droplets from aggregation. Yi et al [29] used cheap and ecofriendly material-lignin as Pickering emulsion stabilizer and the active hydroxyl groups in the chemical structure of lignin could react with isocyanate groups in oil phase and reinforced the stability of emulsions. Isophorone diisocyanate, (IPDI) was effectively loaded in lignin nanoparticle-stabilized oil-in-water (O/W) Pickering emulsion templates ( Figure 2).…”

Facile Preparation and Functionalization of Cellulose Microgels and their Properties and Application in Stabilizing O/W Emulsions

“…Examples include silica nanoparticles (Vignati et al 2003;Simovic and Prestidge 2004;Huo et al 2014), clay (Yang et al 2006), and latex particles (Giermanska-Kahn et al 2002;Walther et al 2008). Recently, Wei et al used a natural polymer, i.e., alkaline lignin extracted from furfural residues, to prepare Pickering emulsions, which can further be used as a template to fabricate composite capsules Yi et al 2015). Over the past decade, this new type of emulsion, i.e., Pickering emulsions, have received increasing attention both in fundamental research and practical applications due to their unique properties such as greater stabilization, relatively well controlled size, lower toxicity, and a reduced rate and extent of creaming/sedimentation owing to the enhanced viscosity of the continuous phase .…”