Study of miniemulsion formulation containing 1-octyl-3-methylimidazolium hexafluorophosphate for its application in low-emitting coating products

Abstract

Room temperature ionic liquids (RTILs) are non-volatile organic salts, and few of them with low melting point may replace the conventional coalescing agents in waterborne coatings, thus preventing volatile organic compounds (VOCs) emission, caused by coalescing agents. The formation of waterborne coating containing RTILs can be achieved by the encapsulation of RTILs inside latexes via miniemulsion polymerization. Achieving a stable miniemulsion is a crucial step for further polymerization. In this study, 1-octyl-3-methylimidazolium hexafluorophosphate (C8mimPF6) was chosen, and various factors which might affect droplet size and its stability, including surfactant type, surfactant concentration, and C8mimPF6 concentration, were investigated. It was found that the presence of a small amount of C8mimPF6 coupled with the surfactant would offer marked effects on the droplet size reduction and droplet stability. Such effect may reach its maximum from 1 to 5 wt% C8mimPF6. Above the critical concentration, adding more C8mimPF6 to the oil phase may cause a larger initial droplet size as well as weaken the droplet stability. Such observations were consistent with the zeta potential measurements for miniemulsions prepared under similar conditions.

Mass transfer and reaction kinetics of soybean oil epoxidation in a formic acid‐autocatalyzed reaction system

“…The droplet size of the two‐phase mixture in this system was measured by Zetasizer (nano series, Malvern Instruments Ltd., UK). This technique has been widely used to measure droplet size …”

Effect of C8mimPF6 on miniemulsion polymerization for application in new latex coating products

“…interfacial space alignment. 20 It has been reported in open literature that the tighter interfacial structure may reduce the entry rate of radicals into droplets. [34][35][36] Thus it would be expected that the number of radicals in droplets/particles, n, would be reduced.…”

“…It is worth mentioning that with the increase in storage time (where no reaction took place), the droplet size of the miniemulsions containing higher concentrations of C 8 mimPF 6 also increased to a similar magnitude. 20 This indicates that although the droplet nucleation appeared to be dominating, the nal particle size of the latex was strongly inuenced by the droplet/particle size at the early stage of the reaction and the storage stability. for the initial 10 min, which conrm the occurrence of micellar or homogeneous nucleation during reaction.…”

“…The effect of RTILs on the initial droplet size and stability of miniemulsions was reported in our earlier work. 20 In this study, 1-octyl-3-methylimidazolium hexauorophosphate (C 8 mimPF 6 ) was chosen as the target RTIL. Two kinds of initiators, hydrophobic 2,2'-azobis(isobutyronitrile) (AIBN) and hydrophilic hydrogen peroxide/ascorbic acid (H 2 O 2 /Vc) were used in the polymerization.…”