Anionic block copolymerization methacrylates

The anionic block copolymerization of methyl methacrylate and glycidyl methacrylate leads to very versatile surface-active agents. The hydrophilic/hydrophobic balance of these amphipatic macromolecules can be easily controlled not only by the relative length of the constitutive blocks but also by the chemical modification of the epoxy groups. The poly(glycidyl methacrylate) block can be easily sulfo-... 

Controlled/Living Anionic Block Copolymerization of Styrenes and Alkyl Methacrylates Using Integrated Flow Microreactor Systems... 

Investigations were also made into surface nanostructures and their reconstruction behavior, by altering the outer environment using a series of block copolymers, namely PS-f)-poly(2-(perfluorooctyl)ethyl methacrylate) [96], PS-b-P(HEMA) [106, 107], and PS-f)-poly[(oligo(ethylene glycol) alkyl ether methacrylate), synthesized by anionic block copolymerization [116-120]. 

Kloninger, C. and Rehahn, M. (2004a) 1,1-dimethylsilacyclobutane-mediated living anionic block copolymerization of [l]dimethylsilaferrocenophane and methyl methacrylate. Macromolecules, 37,1720. 

The anionic polymerization of masked disilenes proceeds via living anions, and therefore block copolymerization with a conventional vinyl monomer is possible. Recently, interesting hydrophobic block copolymer of PMHS with poly(2-hydroxyethyl methacrylate) (PHEMA) and poly(methacrylic acid) (PMMA) have been prepared (Scheme 11). These polymers can be self-assembled and are transformed into polysilane micelles, shell cross-linked micelles (SCM), and nanometer-sized hollow particles. ... 

The limitations to living block copolymerization arise when the anionic addition site is unable to initiate the polymerization of the second monomer. An example is the methacrylate anion formed with lithium, which is unable to initiate the polymerization of styrene. This contrasts with the reverse situation in which the polymerization of methyl methacrylate may be initiated by polystyryl lithium (Cowie, 1989a). Thus the synthesis of a PS-PMMA block copolymer by an anionic route requires first the polymerization of styrene and then addition of methyl methacrylate. 

Sterically bulkier 2,6-diisopropylphenyl (16c), 2,6-di(tert-butyl)-4-methylphenyl (16d), and 2,6-di(tert-butyl)-4-methoxyphenyl esters (16e) were more effective to protect the carboxylic acid of 16. These ester-protected styrene monomers, 16c-16e, underwent living anionic polymerization without any side reaction in THF even at -78 °C. The resulting living polymers were stable for 24 h under such conditions. Polymers with predictable molecular weights and narrow molecular weight distributions (A4w/A4n< 11) were quantitatively obtained. The success of postpolymerization and the sequential block copolymerization with tert-butyl methacrylate (tBMA) further supports the living nature of the polymerization of 16c-16e. Thus, tert-butyl and sterically bulkier phenyl esters satisfactorily protect the carboxylic acid function of 16 to enable the living anionic polymerization of their ester-protected monomers. 

The living anionic polymers of protected functional methacrylate monomers herein introduced are very similar in reactivity and stability to those of MMA. Accordingly, these living polymers can initiate the polymerization of MMA, tBMA, and other protected functional methacrylate monomers, resulting in block copolymers with tailored chain structures. Complete aossover block copolymerizations among these methacrylate monomers are possible. Furthermore, living anionic polymers of styrene, a-methylstyrene, isoprene, and 1,3-butadiene initiate the polymerization of protected functional methacrylate monomers to afford well-defined AB diblock copolymers. In order to avoid ester carbonyl attack by the chain-end anions, the living anionic polymers should be end-capped with 1,1-diphenylethylene... 

The statistical anionic copolymerization of acrylates and methacrylates is also controlled in the presence of LiOEEM (30), as testified by the copolymerization of MMA and tBuA in THF at —78°C. Block copolymers were also prepared by the sequential polymerization of at least two methacrylates and acrylates. For instance, PMMA- >/c cA -PbBuA and PMMA-fcZocA -PnNonA were synthesized . The addition order of the comonomers is important. Indeed, when living PnBuA is the macroinitiator of the MMA polymerization, the expected block copolymer is contaminated by homo-PnBuA, which is not the case when the polymerization sequence is reversed. A fuUy acrylic-based thermoplastic elastomer, PMMA-fcZocA -P(2EtHA)-fcZocA -PMMA, was prepared by the sequential LiOEEM-ligated polymerization of MMA, 2-EtHA and MMA. ... 

Novel sulfonated and carboxylated ionomers having "blocky" structures were synthesized via two completely different methods. Sulfonated ionomers were prepared by a fairly complex emulsion copolymerization of n-butyl acrylate and sulfonated styrene (Na or K salt) using a water soluble initiator system. Carboxylated ionomers were obtained by the hydrolysis of styrene-isobutyl-methacrylate block copolymers which have been produced by carefully controlled living anionic polymerization. Characterization of these materials showed the formation of novel ionomeric structures with dramatic improvements in the modulus-temperature behavior and also, in some cases, the stress-strain properties. However no change was observed in the glass transition temperature (DSC) of the ionomers when compared with their non-ionic counterparts, which is a strong indication of the formation of blocky structures. 

Both emulsion copolymerization of butyl acrylate/sulfonated styrene with a water soluble initiation system, and anionically synthesized diblock ionomers based on the ester hydrolysis of methacrylate blocks show novel and quite similar characteristics. Both systems show no effect of ion content on the Tg of the matrix however provide a highly extended rubbery plateau to the resulting ionomers. 

Solvents influence the rate of free-radical homopolymerization of acrylic acid and its copolymerization with other monomers. Hydrogen-bonding solvents slow down the reaction rates. Due to the electron-withdrawing nature of the ester groups, acrylic and methacrylic ester polymerize by anionic but not by cationic mechanisms. Lithium alkyls are very effective initiators of a-methyl methacrylate polymerization yielding stereospecific polymers.Isotactic poly(methyl methacrylate) forms in hydrocarbon solvents. Block copolymers of isotactic and syndiotactic poly(methyl methacrylate) form in solvents of medium polarity. Syndiotactic polymers form in polar solvents, like ethylene glycol dimethyl ether, or pyridine. This solvent influence is related to Lewis basicity in the following order ... 

Block copolymers 2.45 and 2.46 were prepared by emulsion copolymerization of styrene and methyl methacrylated terthiophenes in the presence of a fluorinated anionic surfactant using K2S2O8 as a... 

Copolymerization of 4-vinylphenyl isocyanate and styrene at 60°C in toluene in the presence of AIBN affords the expected copolymers (44). Also, 1 1 copolymers from vinyl isocyanate and maleic anhydride are known (54). The copolymeriation of n-butyl isocyanate with a variety of olefins is conducted in toluene/THF at —80°C, using sodium biphenyl as initiator (55). Anionic copolymerization of styrene and hexyl isocyanate affords rod-coil block copolymers. The st5Tene polsrmer forms the coil block, while the polyisocyanate block assumes the rod shape (56). Vinyl-, 9-decenyl-, or y3-allyloxyethyl isocyanate imdergoes copolymerization reactions with styrene or methyl methacrylate (57). 

Early work on alkyl methacrylate anionic copolymerizations by Graham and co-workers showed that the polystyrene living anion could initiate MMA monomer to incorporate it and form polystyrene-b-PMMA block copolymer, but that styrene is inert to the PMMA anion. Later they demonstrated the incorporation of various ther alkyl methacrylates into block copolymers with PMMA. " ... 

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