Methacrylic surfmer

Maleate Surfmers were found to outperform methacrylic and crotonic compounds in the copolymerization of styrene, butyl acrylate and acrylic acid in seeded and nonseeded semicontinuous processes [17]. The maleate Surfmer achieved high conversion without homopolymerization in the aqueous phase which can result in emulsion instability. The methacrylate Surfmer was too reactive as opposed to the crotonate which was not sufficiently reactive. The reported dependence of the maleate Surfmer conversion on the particle diameter is consistent with a reaction at the particle surface. 

One way to achieve this result relies on the change in the relative monomer reactivity following composition drifts. Thus, in a combination ofhigh and low reactivity monomers, the former will preferentially react first, leaving a considerable proportion of the latter for copolymerization when the supply of the high reactive monomer is depleted. This has been confirmed in the terpolymerization of methyl methacrylate/butyl acrylate/vinyl acetate in the presence of the maleate Surfmer reported in Figure 6.49. 

The maleic Surfmers were tested in core-shell emulsion polymerization of styrene/butyl acrylate in comparison with a standard nonreactive surfactant (nonyl phenol reacted with 30 mol of EO - NP30). While the methacrylic-derived Surfmer was completely incorporated during the polymerization (although about one-third of it was buried inside the particles) the NP30, the maleic Surfmer and the allylic and vinyl Surfmers were not incorporated and could be extracted with acetone (for the last two probably because of the formation of acetone-extractable oligomers due to a chain transfer behavior) [31]. 

Recently Uniqema has introduced commercially a Surfmer under the trade name of Maxemul 5011. Maxemul is produced by esterification of an unsaturated fatty anhydride with a methoxy PEG such that the reactive group is close to the hydrophilic moiety [ 34 ]. Stable latexes with a solid content of 52% were produced in the seeded emulsion polymerization of film-forming methyl methacrylate/butyl acrylate/acrylic acid (3% Surfmer on monomers, constant monomer feeding rate over 4 h, potassium persulfate/sodium metabisulfate redox initiator). The latexes were stable to electrolytes but not to freeze-thaw. 

Recently, this kind of surfmer was studied in more detail [43] in the copolymerization of styrene, butylacrylate, and acrylic acid (49 49 2) in semi-continuous (seeded or nonseeded) protocols at 30% or 50% solid contents recipes, on the basis of kinetics (both overall and instantaneous whole conversion), evaluation of the surface tension, and amount of coagulum produced. The reactivity ratios with the comonomer have also been measured for the reaction that took place in water phase, and a two-phase titration technique has been developed to analyze the conversion of the surfmers. The behavior of these surfactants was compared to that of a methacrylic compound and a crotonic compounds (IX and X of Table 3). 

The acylation of alcohol-containing monomers, such as hydroxyethyl acrylates and methacrylates or vinylbenzyl alcohol, with maleic, or succinic, or sulfosuccinic anhydride, allows easy preparation of bifunctional polymerizable surfactants [64]. Some among these compounds, listed in Table 5, have been engaged in batch polymerization of styrene as well as in core-shell copolymerization of styrene and butyl acrylate. Stable latexes have been obtained in both cases, with only low floe production. A high conversion of the surfmers was most often reached, with little burying. However, these latexes do not show a noticeable resistance to the addition of electrolytes and cannot withstand freezing tests these features are not so surprising because their stabilization is only electrostatic and in no way steric. It can be noted, however, that their water rebound is somewhat limited, unless their water... 

Another estimate of the incorporation yield of a styrenic surfmer of polyethylene oxide in batch copolymerization with styrene has been published recently. The polyethylene oxide absorbance can be estimated (using NMR) in the latex produced [72]. The incorporation yield was shown to be between 7-42%, most of the surfactant remaining in the serum. Latex stabillity involves a long enough polyoxyethylene sequence (around 50 units). At variance with saccharide surfactants [73], copolymerization of the styrene with a more hydrophilic monome such as methyl methacrylate tends to reduce the incorporation yield. 

Lansalot and coworkers very recently reported a new strategy for the synthesis of iron-oxide nanoparticles using a functional monomer approach (Joumaa et al, 2008). By selectively designing a functional monomer with a pendant reactive phosphate group, which can selectively interact with the iron particles, the successful incorporation of these particles into the polymer nanoparticles was achieved. This monomer was utilized as a surfmer and displayed a phosphate group at one extremity and a polymerizable methacrylic functionality at the other one that are separated by a short poly(ethylene) glycol spacer. 

Miniemulsion polymerization of styrene and -butyl methacrylate was used by Pich et al. [64] to prepare polymeric particles by using a fluorinated comonomer that acts as a surfmer providing... 

---