Glass‐transition temperature of a polyacrylate latex film and its water whitening resistance

Abstract

Polyacrylate latex materials have become a hot area recently in China due to its environmental friendliness. However, the water whitening resistance of the polyacrylate latex products in the market is largely unsatisfactory, which seriously affects the appearance and performance of the latex products. In this work, the effect of glass‐transition temperature (Tg) of a polyacrylate latex film on its water whitening resistance was investigated. The light transmittance measurement showed that the higher the Tg of the latex film, the better the water whitening resistance. Atomic force microscope, surface element analysis, static water contact angle measurement, and attenuated total reflection–Fourier transform infrared were used to characterize the accumulation of the emulsifier on the surface of the latex film. It was found that the amount of emulsifier migrated to the surface of the latex film increased with the increase of the Tg of the latex film, that is, the amount of emulsifier remained inside the latex film decreased, thereby reducing its affinity to water. In addition, the higher the Tg of the latex film, the lower the water absorption, also reducing the affinity of the latex film to water. Both work together to improve the water whitening resistance of polyacrylate latex film with higher Tg. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48361.

Effect of acrylic acid on water‐whitening resistance of polyacrylate latex films and its mechanism

“…However, the fact was the opposite, that is, the surface of H series latex film showed greater hydrophilicity. This seemingly abnormal phenomenon was clearly explained in our previous work 27 …”

“…Our group 27 once studied the influence of T g on the water‐whitening resistance of a latex film, and found that the latex film with a higher T g was more resistant to water whitening than that with a lower T g . The results in this work can further verify our previous conclusion.…”

Coupled effect of water absorption and ion transport in hydrated latex anti-corrosion coatings

“…Another important aspect, polymer mechanical properties also influence water absorption. Crosslinking between polymer chains 7,8,22 and higher glass transition temperature (T g ) 20,23,24 both reduce water absorption. Finally, both covalently and non-covalently bound emulsifiers have a significant effect on water absorption, as increasing emulsifier concentration raises water absorption.…”

Amphiphilic Statistical Copolymers from Catalytic Chain Transfer as Reactive Surfactants in Emulsion Polymerization

“…They not only control the colloidal stability of the particles in the latex, but the type and architecture of the used surfactant also have a large influence on the physical and rheological properties of the latex and thus on the final application. − In most cases, surfactants are not covalently bound to the colloidal particles; therefore, surfactants can desorb over time. Furthermore, during film formation, surfactants can migrate from the colloidal particles toward the film surface and have a negative effect on film properties such as adhesion strength, peel strength, water resistance, gloss, and blocking. − To circumvent these negative effects, reactive surfactants that are chemically bound to the polymer particles can be used. − An ideal reactive surfactant should not be too reactive at the start of the emulsion polymerization, in order to avoid the chemically bound surfactant molecules from being buried inside the latex particles, but at the end of the emulsion polymerization, all surfactants should have reacted to obtain a stable latex. − Reactive surfactants containing a propenyl end-group are promising candidates displaying the right reactivity, and methacrylic oligomers containing these end-groups (called macromonomers in the remainder of this paper) are readily prepared via catalytic chain transfer polymerization (CCTP), , and their subsequent copolymerization behavior has been subscribed previously. − In earlier studies, amphiphilic macromonomers were synthesized and subsequently used as stabilizers in an emulsion polymerization. − In our earlier work, methacrylic acid (MAA) macromonomers were synthesized via CCTP and were used directly in an emulsion polymerization to form in situ amphiphilic copolymers, in a mechanism similar to what is commonly known as polymerization-induced self-assembly. − Only in the cases where the MAA macromonomers were sufficiently fast converted into amphiphilic copolymers, stable latexes could be produced. In another study, a two-step copolymerization of MAA macromonomers with methyl methacrylate (MMA) or butyl acrylate (BA) gave amphiphilic stabilizers suitable for the emulsion polymerization with MMA, albeit the rheology and physical properties of the systems were rather different .…”