Methacrylate higher alkyl

Most large-scale industrial methacrylate processes are designed to produce methyl methacrylate or methacryhc acid. In some instances, simple alkyl alcohols, eg, ethanol, butanol, and isobutyl alcohol, maybe substituted for methanol to yield the higher alkyl methacrylates. In practice, these higher alkyl methacrylates are usually prepared from methacryhc acid by direct esterification or transesterification of methyl methacrylate with the desired alcohol. 

Transesterification of methyl methacrylate with the appropriate alcohol is often the preferred method of preparing higher alkyl and functional methacrylates. The reaction is driven to completion by the use of excess methyl methacrylate and by removal of the methyl methacrylate—methanol a2eotrope. A variety of catalysts have been used, including acids and bases and transition-metal compounds such as dialkjitin oxides (57), titanium(IV) alkoxides (58), and zirconium acetoacetate (59). The use of the transition-metal catalysts allows reaction under nearly neutral conditions and is therefore more tolerant of sensitive functionality in the ester alcohol moiety. In addition, transition-metal catalysts often exhibit higher selectivities than acidic catalysts, particularly with respect to by-product ether formation. 

Methyl and ethyl methacrylate polymers, although extensively used in Industry, do not possess the solubility characteristics (low polarity) that would make them appropriate for use over traditional oil paintings and other organic-based museum objects that might be sensitive to polar solvents such as alcohols, ketones and esters. Poly(n-butyl methacrylate), offered as an artists varnish in the late 1930 s, did not become widely accepted in the war-disrupted decade that followed. Accordingly, early in 1951, our laboratory began a detailed study of the higher alkyl methacrylate polymers for potential use as picture varnishes (1). 

Later investigations have fully confirmed the conclusion that the crosslinking of the higher alkyl methacrylate polymers will take place on a gallery wall. We have been able to demonstrate that an induction time of about 11 years occurs before insoluble matter begins to form in commercial normal and isobutyl polymers on a well-illuminated museum wall (1,11). Protection against such loss of solubility is one of a number of reasons for recommending the use of ultraviolet filters over windows and over fluorescent-lamp sources in museums (12). 

Tn the early 1960s it was discovered in our laboratory (20) that poly-- (methyl methacrylate) (PMMA) and poly(vinylidene fluoride) (PVdF) were compatible when blended in the melt. Similarly, compatibility was found for poly (ethyl methacrylate) (PEMA) with PVdF. Blends of the fluorinated polymer with higher alkyl methacrylate polymers, however, were nonhomogeneous. 

Higher -alkyl methacrylate polymers have commercial applications. Poly( -butyl-), poly( -octyl-) and poly( -nonyl methacrylate)s are used as leather finishes poly(lauryl methacrylate) is used to depress the pour point and improve the viscosity-temperature property of lubricating oils. 

In 1950, Dahlquist et al. [82] reported the use of polyvinyl A -alkyl carbamates as PSA release materials. Since then, many other types of alkyl side chain polymers have been patented for use as release coatings, including copolymers based on higher alkyl acrylates or methacrylates [83-86], polyvinyl esters of higher aliphatic fatty acids [87], higher alkyl vinyl esters or ethers and a maleic... 

The controlled polymerisation of higher alkyl methacrylates and stearyl methacrylate has also been successfully achieved by the bulk atom transfer radical polymerisation technique at ambient temperature in the presence of CuCl/PMDETA/tricaprylyl methyl ammonium chloride (Aliquatw336)... 

D. P. Chatterjee and B. M. Mandal, Fadle atom transfer radical homo and block copolymerization of higher alkyl methacrylates at ambient temperature using CuCl/PMDETA/quatemaryarmnonium halide catalyst system . Polymer, 2006, 47,1812-19. 

Plasticizers These are required to reduce the inherent brittleness of poly(alkyl-2-cyanoacrylates). This can be achieved by using non-copolymerizing plasticizers such as esters or higher alkyl cyanoacrylates, which copolymerize with the basic adhesive monomer. Toughness properties can be improved by the inclusion of rubber toughening materials such as ABS (acrylonitrile-butadiene-styrene) or MBS (methacrylate-butadiene-styrene) copolymers. Whichever approach is adopted, toughness is only achieved at the expense of reduced cure speed. 

After experiencing difficulty in gaining consistent polymerization results, especially with the higher alkyl methacrylates, it was decided that the search for a new purification technique should be initiated. As residual alcohols are the major impurity in most alkyl methacrylates, purification agents which react with alcohols (and water) but do not react with methacrylates were sought. Initial experiments were with conventional organic... 

Acrylic Esters. A procedure has been described for preparation of higher esters from methyl acrylate that illustrates the use of an acid catalyst together with the removal of one of the products by azeotropic distillation (112). Another procedure for the preparation of butyl acrylate, secondary alkyl acrylates, and hydroxyalkyl acrylates using -toluenesulfonic acid as a catalyst has been described (113). Alurninumisopropoxide catalyzes the reaction of amino alcohols with methyl acrylate and methyl methacrylate. A review of the synthesis of acryhc esters by transesterification is given in Reference 114 (see... 

A number of higher n-alkyl methacrylate polymers have found commercial usage. The poly-(n-butyl-), poly-(n-octyl-) and poly-(n-nonyl methacrylate)s have found use as leathering finishes whilst polyflauryl methacrylate) has become useful as a pour-point depressant and improver of viscosity temperature characteristics of lubricating oils. 

A large number of organic acrylic ester polymer have been prepared in the laboratory. Poly (methyl acrylate) is tough, leathery and flexible. With increase in chain length there is a drop in the brittle point but this reaches a minimum with poly-(n-octyl acrylate) (see Figure 15.12.). The increase in brittle point with the higher acrylates, which is similar to that observed with the poly-a-olefins and the poly(alkyl methacrylate)s, is due to side-chain crystallisation. 

Values of kjkli for polymerizations of EM A and BMA and higher methacrylate esters have been determined.11 lIl>1V7 l5i The extent of disproportionation increases with the size of the ester alkyl group. 

Very large solvent effects arc also observed for systems where the monomers can aggregate either with themselves or another species. For example, the apparent kp for polymerizable surfactants, such as certain vinyl pyridinium salts and alkyl salts of dimethylaminoalkyl methacrylates, in aqueous solution above the critical micelle concentration (cmc) are dramatically higher than they are below the cmc in water or in non-aqueous media.77 This docs not mean that the value for the kp is higher. The heterogeneity of the medium needs to be considered. In the micellar system, the effective concentration of double bonds in the vicinity of the... 

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