Polymethylmethacrylate-methacrylic

The "comb" dispersing agent was a graft copolymer of polymethylmethacrylate-methacrylic acid (methoxypolyethylene oxide methacrylate) supplied by ICI Paints Division (Slough) and used as received. The exact molecular weight of the polymer is not known, but it is ejqpected to be in the region of 20-30,000 (as indicated by ICI Paints Division). The of the polyethylene chains was 750. 

A C-NMR spectrum of a polymethylmethacrylate - methacrylic acid copolymer is shown in Figure 3.19 (a). The spectrum demonstrates the acidic group and the ester group resonances. 

ACPA azobis(4-cyanopentanoic acid) AIBN azobis isobutyronitrile) BPO benzoyl peroxide DVB divinyl benzene, EGA 2-ethylcyano-acrylate HPC hydroxypropyl cellulose MMA methyl methacrylate PAAc polyacrylic acid PEI polyethyleneimine, PEO/PPO polyethylene oxide/polypyropylene oxide copolymer PVME polyvinylmethylether PVP polyvinylpyrrolidone K-30 DMSO dimethylsulfoxide PGA polyglutaraldehyde CMS chloromethylstyrene PMMA-g-OSA polymethylmethacrylate grafted oligostearic acid. 

A detailed study of the mechanism of the insertion reaction of monomer between the metal-carbon bond requires quantitative information on the kinetics of the process. For this information to be meaningful, studies should be carried out on a homogeneous system. Whereas olefins and compounds such as Zr(benzyl)4 and Cr(2-Me-allyl)3, etc. are very soluble in hydrocarbon solvents, the polymers formed are crystalline and therefore insoluble below the melting temperature of the polyolefine formed. It is therefore not possible to use olefins for kinetic studies. Two completely homogeneous systems have been identified that can be used to study the polymerization quantitatively. These are the polymerization of styrene by Zr(benzyl)4 in toluene (16, 25) and the polymerization of methyl methacrylate by Cr(allyl)3 and Cr(2-Me-allyl)3 (12)- The latter system is unusual since esters normally react with transition metal allyl compounds (10) but a-methyl esters such as methyl methacrylate do not (p. 270) and the only product of reaction is polymethylmethacrylate. Also it has been shown with both systems that polymerization occurs without a change in the oxidation state of the metal. 

Polymeric particles can be constructed from a number of different monomers or copolymer combinations. Some of the more common ones include polystyrene (traditional latex particles), poly(styrene/divinylbenzene) copolymers, poly(styrene/acrylate) copolymers, polymethylmethacrylate (PMMA), poly(hydroxyethyl methacrylate) (pHEMA), poly(vinyltoluene), poly(styrene/butadiene) copolymers, and poly(styrene/vinyltoluene) copolymers. In addition, by mixing into the polymerization reaction combinations of functional monomers, one can create reactive or functional groups on the particle surface for subsequent coupling to affinity ligands. One example of this is a poly(styrene/acrylate) copolymer particle, which creates carboxylate groups within the polymer structure, the number of which is dependent on the ratio of monomers used in the polymerization process. 

Another very important visible light-initiated reaction of alkyl aluminum porphyrins is their 1,4-addition to alkyl methacrylates to produce ester enolate species [Eq. (4)]. This enolate then acts as the active species in the subsequent polymerization of the acrylate monomer. For example, Al(TPP)Me acts as a photocatalyst to produce polymethylmethacrylate with a narrow molecular weight distribution in a living polymerization process [Eq. (4)]. Visible light is essential for both the initiation step (addition of methylmethacrylate to Al(TPP)Me) and the propagation... 

Copolymerization of 3-chlorostyrene with glycidyl methacrylate to form GMC, resulted in G(x) increasing from 0.61 to 1.02 and G(s) from 0.16 to 0.42. Polyalkylmethacrylates are well-known to undergo main chain scission upon irradiation (10,23-6) e.g., polymethylmethacrylate has a G(x) =0 and G(.y) = 1.4(27). The increase in G(s) can therefore be attributed entirely to the presence of the methacrylate moiety. The enhanced G(x) value of GMC arises from the epoxide ring opening upon exposure and initiating cross-linking. 

Triplet—triplet energy transfer from benzophenone to phenanthrene in polymethylmethacrylate at 77 and 298 K was studied by steady-state phosphorescence depolarisation techniques [182], They were unable to see any clear evidence for the orientational dependence of the transfer probability [eqn. (92)]. This may be due to the relative magnitude of the phosphorescence lifetime of benzophenone ( 5 ms) and the much shorter rotational relaxation time of benzophenone implied by the observation by Rice and Kenney-Wallace [250] that coumarin-2 and pyrene have rotational times of < 1 ns, and rhodamine 6G of 5.7 ns in polymethyl methacrylate at room temperature. Indeed, the latter system of rhodamine 6G in polymethyl methacrylate could provide an interesting donor (to rose bengal or some such acceptor) where the rotational time is comparable with the fluorescence time and hence to the dipole—dipole energy transfer time. In this case, the definition of R0 in eqn. (77) is incorrect, since k cannot now be averaged over all orientations. 

The independent measurements of surface tension were obtained by the tedious Wilhelmy plate method. Figure 3 illustrates such a calibration curve for one set of orifices and for five types of test fluids (methanol-water, ethanol-water, acetone-water, sodium lauryl sulfate in water saturated with methyl methacrylate, and polymethylmethacrylate latices). This is a "universal" calibration curve independent of the fluid being monitored. For the 63 data points shown in Figure 3, the least squares regression line is given by... 

The ruthenium catalyst RuCl2(= CHPh)(PCy3)2 is able to promote both alkene metathesis polymerization (ROMP) and atom transfer polymerization (ATRP) [80,81]. The bifunctional catalyst A was designed to promote both ROMP of cyclooctadiene (COD) and ATRP of methyl methacrylate (MMA). Thus, catalyst A was employed to perform both polymerizations in one pot leading to diblock polybutadiene/polymethylmethacrylate copolymer (58-82% yield, PDI = 1.5). After polymerization the reaction vessel was exposed to hydrogen (150 psi, 65 °C, 8h), under conditions for Ru(H2)(H)Cl(PCy3)2 to be produced, and the hydrogenation of diblock copolymer could attain 95% [82] (Scheme 36). 

Polymethylmethacrylate (Lucite, Plexiglas, Crystallite or PMMA). A thermoplastic translucent resin of the acrylate resin family. The monomer, methyl methacrylate ... 

In addition to these irregularities, Winey et al. (1996) have found that in random and alternating copolymers of styrene and methyl methacrylate, the sequence distribution of monomers along the backbone of the polymer strongly affects its miscibility with polystyrene and polymethylmethacrylate homopolymers, even when the overall ratio of styrene/methyl methacrylate in the copolymer chain is held constant. A strictly alternating sequence of monomers in the copolymer was found to be more miscible with the ho-miopolymers than is a copolymer with a random sequence distribution. These results... 

The influence of preformed stereoregular polymethylmethacrylate on the polymerization mechanism is particularly interesting. Grignard compounds at — 50 C in toluene give syndiotactic poly(methylmethacrylate) when preformed isotactic poly(methyl-methacrylate) is present, and vice versa [30,31]. In this replica polymerization, the primary structure formed is the 1 1 (isotactic/syndiotactic) complex. Further association between this complex and syndiotactic macromolecules results in the 1 2 (isotactic/syndiotatic) complex [32]. In the absence of preformed polymer, isotactic poly(methylmethacrylate) was obtained under the same conditions. 

Most recently the polymerization of methyl methacrylate with Ba counterion has been reported. In THF at —70 °C the rate constant for propagation is independent of the active centre concentration and growth seems to occur via ion pair species only. The kinetic data obtained compare favourably with those for polymethylmethacryl sodium and caesium.As before, active centres are terminated by side-reactions involving the ester group. 

In macromolecular chemistry helically wound carbon chains are well known. In isotactic polypropylene (Fig. 6) the methyl groups are arranged on a helix. Some other chiral polymers form helices, like polymethylmethacrylate, polytriphenylmethyl-methacrylate poly-l,2-butadiene and poly-tert-butylethylene oxide... 

Kato et al. (92) irradiated polymethylmethacrylate at -196° C under vacuum, and the spectrum shown in Fig. 16 was obtained. This spectrum was identified as due to the free radicals, COOCH3, CHO, and -CH3, which show the singlet, doublet and quartet, respectively. The half-life of methyl radicals at — 196° C was about 5 hr. It is likely that the methyl radicals are produced by the photolysis of ester side groups, just as ethyl radicals are produced after irradiation of polyethyl-methacrylate at —196° C. 

The thermal volatilization analysis of a mixture of polyvinylchloride and polystyrene is given in Fig. 81. The first peak corresponds to the elimination of HC1 and the second to that of styrene. Dehydrochlorination is retarded in the mixture. The production of styrene is also retarded styrene evolution, in fact, does not occur below 350°C. This contrasts with the behaviour of polyvinylchloride-polymethylmethacrylate mixtures for which methacrylate formation accompanies dehydrochlorination. The observed behaviour implies that, if chlorine radical attack on polystyrene occurs, the polystyrene radicals produced are unable to undergo depolymerization at 300° C. According to McNeill et al. [323], structural changes leading to increased stability in the polystyrene must take place. This could also occur by addition of Cl to the aromatic ring, yielding a cyclohexadienyl-type radical which is unable to induce depolymerization of the styrene chain. 

Evolution of hydrogen chloride from polychloroprene is unaffected by the presence of the second polymer. The system does not show any increased production of methacrylate monomer in the early stage of breakdown as was observed for mixtures of polyvinylchloride and polymethylmethacrylate. 

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