Water-Resistant Latex Coatings: Tuning of Properties by Polymerizable Surfactant, Covalent Crosslinking and Nanostructured ZnO Additive

Abstract

This paper deals with the development of acrylic latexes providing high-performance water-resistant coatings. For this purpose, mutual effects of anionic surfactant type (ordinary and polymerizable), covalent intra- and/or interparticle crosslinking (introduced by allyl methacrylate copolymerization and keto-hydrazide reaction, respectively) and ionic crosslinking (provided by nanostructured ZnO additive) were investigated. The latexes were prepared by the standard emulsion polymerization of methyl methacrylate, butyl acrylate and methacrylic acid as the main monomers. The addition of surface-untreated powdered nanostructured ZnO was performed during latex synthesis, resulting in stable latexes comprising dispersed nanosized additive in the content of ca 0.9-1.0 wt.% (based on solids). The coating performance with emphasis on water resistance was evaluated. It was determined that the application of the polymerizable surfactant improved coating adhesion and water-resistance, but it wasn′t able to ensure high water-resistance of coatings. Highly water-resistant coatings were obtained provided that covalent intra- and interparticle crosslinking together with ionic crosslinking were employed in the coating composition, forming densely crosslinked latex films. Moreover, coatings comprising nanostructured ZnO additive displayed a significant antibacterial activity and improved solvent resistance.

Effect of Fluorinated Comonomer, Polymerizable Emulsifier, and Crosslinking on Water Resistance of Latex Coatings

“…The networking in these copolymers could be ascribed to intermolecular chain transfer reactions to the polymer owing to BA copolymerization [75,76]. When comparing corresponding copolymers differing in emulsifier type, a higher degree of crosslinking was always determined in the case of the H-designed copolymers, which may indicate a higher molecular weight of the copolymers prepared using the polymerizable emulsifier [77] on the one hand, or to a higher quality of coalescence and polymer chain interdiffusion in the case of the polymerizable-emulsifier-based films on the other hand.…”

Surfactant-free latexes as binders in paint applications

“…Later, the solvent evaporates releasing volatile organic compounds. As environmental regulations have imposed severe restrictions to the use of coalescent agents, multiphase polymer particles [3][4][5][6][7][8] and crosslinking using covalent [9][10][11][12], ionic [13], and hydrogen [14,15] bonds are used to overcome the film formation paradox.…”

“…A way of avoiding surfactant migration is to attach it covalently to the polymer by using reactive surfactants (surfmers) [10,17]. The main difficulty using surfmers is that the surfmer should be reactive enough to be fully incorporated at the end of the process and not too reactive to avoid burying during the semicontinuous process [18].…”

Synthesis of Cross‐Linked Block Copolymer Nanoassemblies and their Coating Application

“…[33,43] As well-known, core-cross-linked block copolymer nanoassemblies dispersed in water have the character, that the hydrophobic block is crosslinked and the block copolymer nanoassemblies are hard to be dissolved or solvated when a cosolvent is added. [34,44] Therefore, coalescence of core-cross-linked block copolymer nanoassemblies is restricted, which makes them unsuitable for coating application, in which mechanical properties and water resistance are essential. [45,46] In comparison, corona-cross-linked block copolymer nanoassemblies can be coalesced more easily than the core-cross-linked ones with or without cosolvents.…”

“…[30,31] Of all the cross-linking moieties, diacetoneacrylamide (DAAM) with adipic acid dihydrazide (ADH) is the most favorable. [32][33] The most remarkable feature of the keto-hydrazide crosslinking reaction is fast curing at room temperature, [34] providing great convenience in synthesis of cross-linked block copolymer nanoassemblies. The second method to prepare crosslinked block copolymer nanoassemblies is based on duringpolymerization cross-linking.…”