Methacrylic acid monomer, determination

Rao and co-workers [62] applied Py-GC and C-NMR to the determination of sequence distribution of butadiene (B) - acrylonitrile (A) - methacrylic acid (M) terpolymers. Sequence distribution was described in terms of six triads (BBB, ABA, ABB, BBA, MBR and AMB) and found to vary with the mode of addition of methacrylic acid monomer. 

Methacrylic acid polymer is iasoluble ia the monomer, which may result ia the plugging of transfer lines and vent systems. Polymers of the lower alkyl esters are often soluble ia the parent monomer and may be detected by an iacrease ia solution viscosity. Alternatively, dilution with a nonsolvent for the polymer such as methanol results ia the formation of haze and can be used as a diagnostic tool for determining presence of polymer. 

Abstract. Auto-accelerated polymerization is known to occur in viscous reaction media ("gel-effect") and also when the polymer precipitates as it forms. It is generally assumed that the cause of auto-acceleration is the arising of non-steady-state kinetics created by a diffusion controlled termination step. Recent work has shown that the polymerization of acrylic acid in bulk and in solution proceeds under steady or auto-accelered conditions irrespective of the precipitation of the polymer. On the other hand, a close correlation is established between auto-acceleration and the type of H-bonded molecular association involving acrylic acid in the system. On the basis of numerous data it is concluded that auto-acceleration is determined by the formation of an oriented monomer-polymer association complex which favors an ultra-fast propagation process. Similar conclusions are derived for the polymerization of methacrylic acid and acrylonitrile based on studies of polymerization kinetics in bulk and in solution and on evidence of molecular associations. In the case of acrylonitrile a dipole-dipole complex involving the nitrile groups is assumed to be responsible for the observed auto-acceleration. 

Q = 1.4 and e = 0.46 were determined from the results of the copolymerization of the complex monomer 26 with methacrylic acid. The reactivity of the MA anion (Q = 0.9, e = —1.0) was affected by coordination to the Co(III) complex. In other words coordination, decreased the electron density of the vinyl group. 

A fluorescent MIP chemosensor for determination of 9-ethyladenine was fabricated [56]. It contained porphyrin as a luminescent functional monomer. The interaction of 9-ethyladenine with the porphyrin quenched the MIP luminescence at 605 nm when excited at 423 nm. The polymer was sensitive to 9-ethyladenine in the range of 0.01-0.1 mM however, it was already saturated at 0.15 mM. The same researchers used vinyl-substituted zinc(II) porphyrin and methacrylic acid as functional monomers for imprinting of (-)-cinchonidine [57]. The MIP luminescence, when excited at 404 nm, was significantly quenched at 604 nm upon binding of (-)-cinchonidine, even in the low concentration range of 0.01-2 mM. 

Zhang s group in China developed monolithic poly(styrene-co-divinylbenzene) CEC column in which EOF is supported by carboxyl groups of polymerized methacrylic acid units (Xiong etal. [51]). In a typical procedure, vinylized 75 mm i.d. capillaries were filled with a mixture of 5% styrene 21, 10% divinylbenzene 22, 5% methacrylic acid 1, and 80% toluene containing 1% azobisisobutyronitrile (in respect to monomers) and polymerized at 70°C for 24 h. The pore volume of 0.098 mL/g and mean pore size of 40 nm determined for this monolith appear to be rather small and do not correspond with the published SEM pictures that reveal existence of large pores, and the chromatographic performance of the columns in CEC mode. 

The material as received contained 8.8% methoxyl group (specified by the supplier) and its lignosulfonate content was 86.8% with reference to the purified material (determined in our laboratory by ultraviolet absorption at 280 nm). Vinyl monomers, namely, methyl acrylate (MA), methyl methacrylate (MMA) and methacrylic acid (MAA) were distilled under vacuum distillation was performed over cupric sulfate and through a copper-ring packed column to remove stabilizers. The central cut of each distilla-... 

Epoxy vinyl ester resins are a special class of unsaturated resin. This resin is made by capping an epoxy resin with methacrylic acid and then dissolving in styrene monomer to the desired viscosity. This gives mechanical properties similar to epoxy resins, but the processibility (low viscosity allowing for resin infusion processes) of an unsaturated polyester resin. As with unsaturated vinyl esters, the most common fire retardant vinyl ester resin is based on a resin made from a halogenated system, tetrabromobisphenol A. The level of bromine in the resin and the presence of antimony will determine the fire performance of the resin. These resins are normally used for corrosion resistant equipment or when fire performance and high mechanical properties are required. It is very difficult to get a low smoke value with a brominated vinyl ester resin again due to the fact that bromine... 

The listed amount of methacrylic acid was contained in the HEM A monomer used to form the poly (HEM A)/Silastic hydrogels, which had 20% grafted poly(HEMA). These hydrogels were equilibrated for 45 hrs at 37°C in 0.5mg/ml protein solutions in the listed solvents and then rinsed in the equilibration solvent, using decantation and dilution and 15 min of stirring. Ninhydrin assays were then used to determine absorbed protein. 

Monomers Polymerizable by Plasma Initiation. Polymerization data for all of the vinyl monomers utilized in this study are summarized in Table 1. As shown previously, methyl methacrylate is readily polymerizable (, ). Methacrylic acid (MAA) and acrylic acid (AA) are polymerized immediately upon exposure to the plasma. Because the resulting polymers are insoluble in their monomers, the products are precipitated out and conversion is low despite prolonged post-polymerization. However, if water is now added as solvent, polymerization becomes homogeneous and high conversions can be readily achieved with post-polymerization. For example, after a 15 second plasma initiation period more than 80% yield was obtained for a 75% aqueous solution of MAA. The molecular weight, determined by intrinsic viscosity measurements, was found to be 4.5 X 10 gm/mole. 

The photoinduced polymerisation of methacrylic acid by sodium peroxide has been determined to have an activation energy of 17.7 kJ/molel03. From this the macroradical lifetimes were determined to be 3.9 secs. In the intermittent photoinitiation of methyl methacrylate-styrene the dependence of the rate of propagation on monomer feed composition was understood in terms of a penultimate model and not a terminal model as previously assumed 4 with some evidence for cross-termination. An eosin-periodate combination has been found to induce the photopolymerisation of acrylonitrile where the dye was found to act as both the sensitiser and reducing agent. Hydroxyl radicals are assumed to initiate polymerisation while the N-bromosuccinimide induced photopolymerisation of N,N -methylenebisacrylamide is faster in 2-propanol solution O . 

Figure 2.6 Control of the graft polymerization as determined with step height measurements of the brush dry tMckness. ETFE substrates were activated with EUV interference lithography. In most cases, the data points roughly follow a square root dependence on the exposure dose. The brush thickness was also influenced by (A) the pH of the graft solution (aqueous solution of methacrylic acid), (B) the viscosity of the solution (GMA in dioxane), controlled by addition of PEG, and (C) the addition of a RAFT agent to the monomer solution (GMA in methylethyl ketone). For details, see the text. Source Figure compiled from Neuhaus et al. [14] and Parquet et al. [15,16] with permission from Elsevier Ltd. and ACS.

A similar approach has been adopted by Whitcombe et al. [15], where NMR chemical shift studies allowed the calculation of dissociation constants and a potential means for predicting the binding capacities of MIPs. The NMR characterization of functional monomer-template interactions has also been applied to the study of the interaction of 2,6-bis(acrylamido) pyridine and barbiturates [16], and of 2-aminopyridine and methacrylic acid [17]. Recent NMR work in our laboratory [18] has involved the determination of template-monomer interactions for a nicotine-methacrylic acid system. Significantly, it was shown in this study that template self-association complexes are present in the prepolymerization mixture and that the extent template self-association is dependent both upon solvent and the presence of monomer. 

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