Acrylic polymers Polyfmethyl methacrylate

Trithiocarbonates (TTC) also offer an interesting alternative platform by dynamic covalent reshuffling reactions of TTC via a free radical mechanism shown in Fig. 15b. It was first introduced into polyfmethyl methacrylate) (PMMA) and polystyrene (PS) gels as a covalent crosslinker, which exhibited dynamic properties [64]. Following this, it was found that the C-S braids of TTC can be photostimulated, and high segmental mobdity of the polymer matrix obtained by RAFT copolymerization of -butyl acrylate (BA) and a TTC crosslinker can facilitate repetitive network repairs using UV radiation at 330 nm [64]. 

Several other types of hydrocarboxylations and hydroesterifications have been conducted with rates and selectivity that are appropriate for the synthesis of fine chemicals and commodity chemicals. One target for hydroesterification has been methyl methacrylate, the monomer of polyfmethyl methacrylate), which is the polymer often called "acrylic". It is estimated that 2.1 million metric tons of methyl methacrylate was produced in 2005. Much of this material is produced from acetone cyanohydrin, but two alternative routes could involve catalytic carbonylation. The first route would involve the hydroesterification of methylacetylene, and this chemistry relates to the original route to methyl methacrylate by carbonylation of methylacetylene using nickel carbonyl as catalyst. The second route involves the sequence of ethylene hydoesterification, aldol addition of the resulting ester to formaldehyde, and dehydration. This sequence comprises Lucite s new "Alpha" process and is shown in Equation 17.33. The route to methyl methacrylate by hydrocarboxylation of ethylene produces water as the only byproduct. 

FIG. 14-19. Plots of log E and log tan 5 against temperature at a frequency of 110 Hz for a two-phase blend of equal weight fractions of polyfmethyl methacrylate) and slightly cross-linked polyfbutyl acrylate). Curves calculated from modified Kemer equation for a polyfmethyl methacrylate) matrix with inclusions of polyfbutyl acrylate) containing 14.4% poly(methyl methacrylate) by volume. (Dickie and Cheung. ) Reproduced, by permission, from the Journal of Polymer Science. 

For vinyl, acrylic, and methacrylic polymers, RIS theory [1] predicts C and K to depend on polymer tacticity. The unperturbed dimensions of stereoregular polymers have been reviewed by Jenkins and Porter [241]. These authors noted that while a large number of studies of unperturbed dimensions have been conducted for such materials, only in a few cases were tacticity or sequence distribution known with certainty. Polyfmethyl methacrylate) is an exception where some careful results on chains of well-defined tacticity exist (Table 9). 

Initial researches into acrylic polymers were concerned rather more with polyacrylates than polymethacrylates. The first acrylic polymer to be produced commercially was polyfmethyl acrylate) production was begun in 1927 by Rohm and Haas AG in Germany. In about 1930, Hill of Imperial Chemical Industries Ltd (UK) prepared cast poly(methyl methacrylate) and... 

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