Fluorinated latexes

No.5, 26th Feb. 2002, p. 1658-62 CONVENIENT SYNTHESIS OF FLUORINATED LATEXES AND CORE-SHELL STRUCTURES BY MINIEMULSION POLYMERIZATION... 

Details are given of the polymerisation of fluoroalkyl acrylate miniemulsions to produce fluorinated latexes. Copolymerisation reactions were also performed with standard hydrophobic and hydrophilic monomers to produce either core-shell latexes or statistical copolymers. Solubilities, molecular weights and particle sizes were investigated. 19 refs. 

The formation of coagulum is observed in all types of emulsion polymers (i) synthetic rubber latexes such as butadiene-styrene, acrylonitrile-butadiene, and butadiene-styrene-vinyl pyridine copolymers as well as polybutadiene, polychloroprene, and polyisoprene (ii) coatings latexes such as styrene-butadiene, acrylate ester, vinyl acetate, vinyl chloride, and ethylene copolymers (iii) plastisol resins such as polyvinyl chloride (iv) specialty latexes such as polyethylene, polytetrafluoroethylene, and other fluorinated polymers (v) inverse latexes of polyacrylamide and other water-soluble polymers prepared by inverse emulsion polymerization. There are no major latex classes produced by emulsion polymerization that are completely free of coagulum formation during or after polymerization. 

EFEP, ETFE, FEP, PCTFE, PEA, PTEE, PTFE micropowders, fluorocarbon elastomers (FKM, fluorinated TPE), FKM latex Fluorosilicones... 

In general, polymerization using a condensed reaction medium can be done in four different modes. While processes for solution polymerizations are already commercialized, dispersion polymerization and emulsion polymerization are not The reason lies in the difficulty of finding a suitable latex stabilizer or alternatively a surfactant that is capable of forming micelles. These additives should not only be C02-compatible but also inexpensive and sustainable. Hence, the fluorinated materials already developed- currently the only ones which perform satisfactorily - are not likely to be applied industrially. Since the present suspension polymerizations are both already relatively green and use inexpensive... 

Fluorinated monomers, 4-(A -adamantylamino)-2,3,5,6-tetrafluorostyrene and 2,3,4, 5,6-pentafluorostyrene, were polymerized in water after complexation with RM-)3-CD without the use of surfactants or cosolvents (Figure 4.17). CD induced high reactivity and formation of stable poly(2,3,4,5,6-pentafluorostyrene) latex particles. The CD ring has a strong influence on copolymerization parameters compared to the uncomplexed monomers. 

The hydrophobic monomers styrene and MMA were copolymerized with the sodium salt of vinylbenzylsulfosuccinic acid as a polymerizable surfactant grafting of the surfactant onto the particles was estimated to be about 50-75% [51]. A polymerizable surfactant was formed by the esterification of hydroxypropylmethacrylate or hydroxyethyhnethacrylate with succinic anhydride [53]. However, in addition to the surfmer, sodium dodecyl sulfate (SDS) was employed to provide a sufficient stability to the latexes. A mono-fluorooctyl maleate surfactant was used to stabilize the polymerization of styrene in miniemulsion [55]. Although the polymerizable moiety was not fixed at the end of the fluorinated chain (the hydrophobe part), the surfactant could be copolymerized with the styrene monomer. Subsequently, on comparison of the infrared (IR) spectra (vibration of -CF2 and -CFj) before and after dialysis, it was estimated that 92% of the surfactant had remained grafted post-dialysis. 

No.6,23rd March 1999, p. 1715-21 LATEX BLENDS OF FLUORINATED AND FLUORINE-FREE ACRYLATES EMULSION POLYMERIZATION AND TAPPING MODE ATOMIC FORCE MICROSCOPY OF FILM FORMATION... 

L. He, J. Liang, X. Zhao, W. Li, H. Luo, Preparation and comparative evaluation of well-defined fluorinated acrylic copolymer latex and solution for ancient stone protection. Prog. Org. Coat. 69 (4) (2010) 352-358. 

X. Xiao, R. Xu, Preparation and surface properties of core-shell polyacrylate latex containing fluorine and silicon in the shell, J. App. Pol. Sci. 119 (3) (2011) 1576-1585. 

The miniemulsion is also well suited to the preparation of copolymers. Here, a mixture of hydrophobic monomers can be used, for example a mixture of styrene and MMA [20] or styrene and butyl acrylate [21], MMA and p-methylstyrene, vinyl hexanoate, or vinyl 2-ethyUiexanoate [22]. Fluorinated monomers can also be copolymerized with monomers such as MMA and styrene [14]. Miniemulsification of such mixed monomer species allows efficient copolymerization reactions to be performed with standard hydrophobic and hydrophilic monomers in a common heterophase situation, resulting either in core-shell latexes or in statistical copoly-... 

K. Li, X.R. Zeng, H.Q. Li, X.J. Lai, Role of acrylic acid in the synthesis of core-shell fluorine-containing polyacrylate latex with spherical and plum blossom-like morphology. J. App. Polym. Sci. 132 (2015) (Article number 42527)... 

All the fluorinated surfactant and wax are initially added to the polymerization reactor. Monomer, initiator, and chain transfer agent can be added incrementally or continuously during the reaction. Pressure is held constant by the addition of the monomer. Upon completion of the polymerization, the product is recovered as latex. Flash evaporation and creaming are the common methods for concentration of the latex. It may be further stabilized by the addition of surfactants. To recover a powder, the latex is coagulated, followed by washing and drying of the polymer. 

---