Hybrid shell microcapsules containing isophorone diisocyanate with high thermal and chemical stability for autonomous self‐healing of epoxy coatings. Issue 22 (29th November 2019)

• Record Type: Journal Article
• Authors: Attaei, Mahboobeh; Vale, Mário; Shakoor, Abdul; Kahraman, Ramazan; Montemor, M. Fátima; Marques, Ana C.
• Is Part Of: Journal of applied polymer science. Volume 137:Issue 22(2020)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2019-11-29
• Subjects: isophoronediisocyanate -- microcapsules -- shelf‐life -- silanes; Polymers -- Periodicals; Polymerization -- Periodicals; 668.9
• DOI: 10.1002/app.48751
• Languages: English
• ISSNs: 0021-8995

Abstract

ABSTRACT: Silica‐polyurea/polyuretane hybrid shell microcapsules (MCs) loaded with isophorone diisocyanate (IPDI) with long shelf‐life and high thermal and chemical stability are prepared via emulsification followed by interfacial polymerization at the surface of oil droplets of the oil‐in‐water emulsion. The resultant MCs are aimed at self‐healing performance in epoxy coatings. A commercially available, highly reactive polyisocyanate named tris( p ‐isocyanatophenyl) thiophosphate is successfully employed as shell forming agent, while triethoxyoctylsilane and hexadecyltrimethoxysilane (HDMS) are tested as "latent" active hydrogen sources. The resulting MCs display core–shell morphology, spherical shape with diameter of 5–20 μm, shell thickness ca. 1–2 μm, and an IPDI core fraction of 69 and 65 wt %, when HDMS and triethoxyoctylsilane are employed, respectively. MCs exhibit an increased thermal stability, comparing with pure IPDI, which makes them robust enough to resist the thermal cycles involved in the coating's preparation. Stability of MCs inside specific solvents and chemicals, their chemical composition and shelf‐life as well as effect of MCs on the epoxy curing are evaluated by Fourier transformed infrared spectroscopy. MCs, remarkably, show excellent environment stability and a long shelf‐life of more than 3.5 months. Their addition to an epoxy formulation is found to heal damaged zones in the epoxy coating, as shown by scanning electron microscopy and electrochemical impedance spectroscopy. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48751. Abstract : Tiny microcapsules (5–20 μm) contain isophorone diisocyanate were synthesized. Highly reactive isocyanate was employed to help the fast formation thin and impermeable shell. Hybrid shell microcapsules show high encapsulation efficiency and long shelf‐life. Microcapsules exhibiting high thermal and excellent chemical resistance.