Methacrylic acid polymerization specificity

Even the earliest reports discuss the use of components such as polymer syrups bearing carboxylic acid functionality as a minor component to improve adhesion [21]. Later, methacrylic acid was specifically added to adhesive compositions to increase the rate of cure [22]. Maleic acid (or dibasic acids capable of cyclic tautomerism) have also been reported to increase both cure rate and bond strength [23]. Maleic acid has also been reported to improve adhesion to polymeric substrates such as Nylon and epoxies [24]. Adducts of 2-hydroxyethyl methacrylate and various anhydrides (such as phthalic) have also been reported as acid-bearing monomers [25]. Organic acids have a specific role in the cure of some blocked organoboranes, as will be discussed later. 

Monomers. A wide variety of monomers can be used, and they are chosen on the basis of cost and abiUty to impart specific properties to the final product. Water solubiUties of iadustriaHy important monomers are shown ia Table 1 (38). The solubiUty of the monomer ia water affects the physical chemistry of the polymerization. Functional monomers like methacrylic and acryUc acid, infinitely soluble ia water, are also used. These monomers impart long-term shelf stabiUty to latices by acting as emulsifiers. The polymerization behavior of some monomers, such as methacrylic acid, as well as the final latex properties are iafiuenced by pH. For optimum results with these acids, polymerization is best performed at a pH of ca 2. After polymerization, the latex is neutralized to give adequate shelf stabiUty at tractable viscosities. 

Synthetic. The main types of elastomeric polymers commercially available in latex form from emulsion polymerization are butadiene—styrene, butadiene—acrylonitrile, and chloroprene (neoprene). There are also a number of specialty latices that contain polymers that are basically variations of the above polymers, eg, those to which a third monomer has been added to provide a polymer that performs a specific function. The most important of these are products that contain either a basic, eg, vinylpyridine, or an acidic monomer, eg, methacrylic acid. These latices are specifically designed for tire cord solutioning, papercoating, and carpet back-sizing. 

As a result of specific interactions, molecules of one component are surrounded by molecules of the second component in the segments of helix form. On the basis of these findings it is possible to assume that similar structures are formed during polymerization of methyl methacrylate in the presence of the isotactic template, or polymerization of methacrylic acid in the presence of poly(L-lysine). However, more experimental results are still needed. 

Inhibitors are introduced al specific points in the process to prevent polymerization Sulfuric acid serves as catalyst in a combined hydrolysis-esterilieaiion of methacrylamide sulfate to a mixture of methyl methacrylate and methacrylic acid. Conversion of methacrylamide sulfate to methyl methacrylate can be carried out using a variety of procedures for die recovery of crude methyl methacrylate and fur separation of methanol and methacrylic acid for recycling. A schematic of the overall process is given in Figure I. The overall yield based on acetone cyanohydrin is approximately 90D Most of Ihe world supply of MMA is still produced by this process. 

Another example of new sorbents is the molecular imprinted polymers (MIP) from the work of Siemann and co-workers (1996). They synthesized a methacrylic acid-ethylene glycol dimethacrylate copolymer with atrazine as an imprint molecule. Imprint synthesis entails polymerization around an imprint species with monomers that are selected for their ability to form specific and definable interactions with the imprint molecule. The atrazine is chemically removed from the polymer leaving holes or cavities. The cavities are formed in the polymer matrix whose size and shape are complementary to that of the imprint molecule (Siemann et al., 1996). These recognition sites enable the polymer to rebind the imprint species selectively from a mixture of closely related compounds, in many instances with binding affinities approaching those demonstrated by antigen-antibody systems. 

The goal of this chapter is to explore the analogy between macromo-lecular complex formation of the labeled probe chain and a polymeric proton donor, such as poly(acrylic acid) (PAA) or poly(methacrylic acid) (PMAA), and the adsorption of the probe chain on colloidal particles such as silica or polystyrene. The basis for a possible analogy between these two situations arises from the nature of the local interactions. Macromolecular complex formation arises from specific interactions such as hydrogen bonding likewise, we expect that similar specific interactions exist between the PEG and the silica or polystyrene substrate. In essence, we consider the macromolecular complex to represent an interaction with a molecular substrate, whereas the colloidal problem involves a solid substrate. 

Triblock and random polyampholytes based on DMAEM-MMA-MAA were examined for their phase separation behaviour [52]. Triblock polyampholytes have a much broader phase separation region than the random ones. The specific structure of PMAA-fc-PlM4VPCl with the excess of cationic or anionic blocks at the lEP is close to the structure of non-stoichiometric IPC. It is suggested that its nucleus consists of intraionic IPC surrounded by cationic blocks protecting it from precipitation [53]. ABC triblock copolymers of polystyrene-b/ock-poly(2-(or 4)vinylpyridine)-fc/ock-poly(methacrylic acid) were synthesized by living anionic polymerization [53 a]. Interpolymer complexation of the polyvinylpyri-dine and poly(methacrylic acid) blocks in the micellar solution was studied in relation to pH in solution by potentiometric, conductimetric and turbidimetric titration and in bulk by FTIR spectroscopy. 

Recently, Takeuchi and coworkers [37] reported the use of molecular imprinting for constructing a highly specific porphyrin-based receptor site. 9-Ethyladenine [37] was chosen as the imprint molecule. Two different functional monomers were utilized to bind 58 during the polymerization process, methacrylic acid (MAA) and a polymerizable zinc-porphorin derivative, 59 (P-53), as shown in Fig. 20. Reference polymers imprinted with 56 were fabricated using either 59 or MAA (P-54 and P-55, respectively) and corresponding nonimprinted, blank polymers were prepared using MAA and 59, MAA, or 57 as functional monomers to form polymers P-56, P-57, and P-58, respectively (Fig. 21). 

Specific types of polymer micropatterns were made of crosslinked and uncrosslinked poly(methacrylic acid) and poly(N-isopropyl acrylamide) or polyNI-PAM. Also, the spacer material between the Si wafers was adjusted to hundreds of micrometers, allowing for a single-exposure high aspect ratio microlithography of theses polymers. Also, since these polymers under go LCST behavior during polymerization conditions, they are suitable as thermoreversible gels during application. 

Semiconductor particles can also be used advantageously in coating applications to provide specific optical response to the material. As an example, Kumacheva et al. recently described the synthesis of monodisperse nanocomposite particles with inorganic CdS nanocrystals sandwiched between a PMMA core and a P(MMA-co-BA) outer copolymer shell layer. The particles are prepared by emulsion polymerization in three steps (Fig. 4.21) [144]. In a first step, polymer latexes are used as host matrices for CdS nanocrystals formation [145,146]. To do so, monodisperse poly(methyl methacrylate-co-methacrylic acid) (PMMA-PMAA) latex particles were ion-exchanged with a Cd(Cl04)2 solution. The Cd + ions thus introduced into the electrical double layer were further reduced into CdS nanoclusters by addition of a Na2S solution. The CdS-loaded nanocomposite particles were subsequently recov-... 

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