Reactivity methacrylates/acrylates

Freidig, A.P., Verhaar, H.J.M., and Hermens, J.L.M. Quantitative structure-property relahonships for the chemical reactivity of acrylates and methacrylates. Environ. Toxicol Chem., 18(6) 1133-1139, 1998. 

Group transfer polymerization allows the synthesis of block copolymers of different methacrylate or acrylate monomers, such as methyl methacrylate and allyl methacrylate [Hertler, 1996 Webster and Sogah, 1989]. The synthesis of mixed methacrylate-acrylate block copolymers requires that the less reactive monomer (methacrylate) be polymerized first. The silyl dialkylketene acetal propagating center from methacrylate polymerization is more reactive for initiation of acrylate polymerization than the silyl monoalkylketene acetal propagating center from acrylate polymerization is for initiation of methacrylate polymerization. Bifunctional initiators such as l,4-bis(methoxytri methyl si loxymethylene)cyclohexane (XXXIII) are useful for synthesizing ABA block copolymers where the middle block is methacrylate [Steinbrecht and Bandermann, 1989 Yu et al., 1988]. 

The main feature of (meth)acrylate-based support materials is the broad diversity of monomers that is commercially available and that can thus can be used for the fabrication of monoliths. The resulting (meth)acrylate monoliths consequently cover a wide spectrum of surface chemistries and properties. The scope of monomers includes hydrophobic, hydrophilic, ionizable, chiral, as well as reactive (meth)acrylate building blocks [53]—the most popular being mixtures of butyl methacrylate and ethylene dimethacrylate (BMA/EDMA) or glycidyl methacrylate and ethylene dimethacrylate (GMA/EDMA) as cross-linker. 

The most widely used UV curable radical-initiated systems are based on acrylate unsaturation with the general formula H2C = CR-COOR (if R = H, the monomer is an acrylatel if R = CH3, it is a methacrylate). Methacrylates are less reactive than acrylates,but are less toxic and cause less skin irritation than acrylates. 

Osman, R., Namboodiri, K., Weinstein, H. and Rabinowitz, J.R. (1988) Reactivities of acrylic and methacrylic adds in a nudeophilic addition model of their biological activity. J. Am. Chem. Soc., 110, 1701-1707. 

Copolymers. Vinyl acetate copolymenzes easily with a few monomers, e g, ethylene, vinyl chloride, and vinyl neodecanoate, which have reactivity ratios close to its own. Block copolymers of vinyl acetate with methyl methacrylate, acrylic acid, acrylonitrile, and vinyl pyrrolidinone have been prepared by copolymerization in viscous conditions, with solvents that are poor solvents for the vinyl acetate macroradical,... 

Poly (methyl methacrylate). Acrylic acid is H2C=CH—COOH and methacrylic acid is H2C=C(CH3)COOH. These compounds and their methyl esters are both quite reactive and difficult to store and handle. The monomer used to form poly (methyl methacrylate), 2-hydroxy-2-methylpropanenitrile, is prepared by the following reaction ... 

For example, the reactivity of acrylic and methacrylic acids is considerably changed in the presence of ZnCl2, SnCl4, triethylaluminium, etc. [95, 96] (see Sect. 4.2). 

A mixture of two monomers that can be homopo-lymerized by a metal catalyst can be copolymerized as in conventional radical systems. In fact, various pairs of methacrylates, acrylates, and styrenes have been copolymerized by the metal catalysts in random or statistical fashion, and the copolymerizations appear to also have the characteristics of a living process. The monomer reactivity ratio and sequence distributions of the comonomer units, as discussed already, seem very similar to those in the conventional free radical systems, although the detailed analysis should be awaited as described above. Apart from the mechanistic study (section II.F.3), the metal-catalyzed systems afford random or statistical copolymers of controlled molecular weights and sharp MWDs, where, because of the living nature, there are almost no differences in composition distribution in each copolymer chain in a single sample, in sharp contrast to conventional random copolymers, in which there is a considerable compositional distribution from chain to chain. Figure 26 shows the random copolymers thus prepared by the metal-catalyzed living radical polymerizations. 

The solid-state reactivity of acrylate esters and salts rmd of acrylamide and its derivatives has long been known (5,6). The lack of crystallographic data has retarded understanding of these systems, and this problem has been recently addressed in the case of metal methacrylates (55). 

It is interesting to note that the addition of a small amount of oxygen into the feed serves to suppress the deactivation of catalyst in the reaction of HCHO with acetic acid. ° However, in the reaction of HCHO with propionic acid, the addition of oxygen is not effective. This may be ascribed to the difference in the reactivity between acrylic acid and methacrylic acid oxygen serves to reoxidize the reduced catalyst in the reaction with acetic acid, but oxygen is consumed in oxidizing methacrylic acid rather than in reoxidizing the reduced catalyst. ... 

Recently [48a] it was reported that Diels-Alder adducts of butadiene with acrylonitrile, acrylamide, methyl methacrylate, acrylic acid, acrolein, and N-phenylmaleimide formed alternating copolymers with SO2. No copolymers were formed from butadiene/maleic anhydride adducts. As the temperature increased the yield decreased. The group on the cyclohexane ring had a considerable effect on the reactivity. 

Real Time (RT-) FTIR spectroscopy pormits not only to follow quantitatively the polymerization by monitoring the disappearance of the IR absorption characteristic of the polymerizable reactive groups (acrylates, methacrylates, epoxy rings, vinyl ether double bonds, thiol groups etc.) but also to determine at any moment the actual degree of conversion and hence the residual imreacted groups content. This analytical method has proved extremely valuable for measuring the polymerization rates and quantum yields of reactions that develop in the millisecond time scale. 

A very important advantage of ATRP for the synthesis of AB block copolymers is the fact that polymerization of monomers such as methacrylates, acrylates, or Sts can proceed regardless of the order of monomer addition therefore, in this case reactivity does not imply a specific and important role in the whole procedure. 

Contact sensitizers from a patient s own materials, such as formaldehyde, isothiazolinones, nickel, chromium, cobalt, colophony (in the form of resin acids), epoxy resin oligomers, reactive diluents, acrylates, methacrylates, polyamines and di-isocyanates, can be analyzed. In fact, any product can be analyzed, but it is not a routine task for laboratories and may be very expensive. There are two main reasons for chemical analyses. First, on patch testing, the patient is found to be allergic to a specific chemical, and the causative product(s) are analyzed for the chemical. Second, the patient s own material has caused an allergic test reaction, but MSDS or other information from the manufacturer did not reveal the causative chemical. In this case, it may be reasonable to analyze the material... 

Dental fields of application of methacrylates are, among others, dental prostheses, composite resins and primers. Methacrylic plastics are formed by polymerization of chemically highly reactive methacrylic monomers. For dental applications, it is most common to use a powder of pre-polymerized (meth)acrylates, which has to be mixed with the right amount of liquid methacrylic monomers. Depending on the polymer-... 

Because of facile cross-propagation, statistical (or nearly random) copolymerization is very easily achieved in free-radical systems, in contrast to ionic reactions. The reactivity of many comonomers are relatively similar. For example, in RP, methacrylates have similar reactivity to styrene and are 3 times more reactive than acrylates. However, in anionic polymerization acrylates are 100 times more reactive than methacrylates and the latter much more reactive than styrene. In cationic polymerization the opposite reactivity order is observed. The copolymerization of monomers with similar reactivity should result in statistical copolymers with no compositional variation during the pol5unerization. This has been observed for copolymerization of the same type of monomers such as various styrenes, various methacrylates, and various acrylates. This is the case for both CRP and conventional RP. However, in batch copol5unerizations of different classes of comonomers there is a continuous change of residual monomer composition in the reaction because one comonomer reacts faster than the other one. 

Vinylesters are unsaturated, hence thermosetting, resins, prepared by the reaction of a monofunctional unsaturated acid, e.g. methacrylic, acrylic, crotonic or cynnamic acid, with a bisphenol diepoxide. This type of structure is referred to as bisphenol-A epoxy vinyl ester (Fig. 4.3(a)). The structural difference, which at least partially justihes the improved chemical and mechanical properties of vinylester, is the presence in vinylesters of reactive double bonds at the ends of the chains only, while unsaturated polyester resins have the reactive double bonds distributed throughout the chains. 

Allyl methacrylate or acrylate can be prepared by alcoholysis of methacrylate acrylate by allyl alcohol in the presence of sodium methylate and a polymerization inhibitor such as hydroquinone [5]. The greater reactivity of the acrylic double bond leads to the formation of a soluble copolymer containing allyl groups that allow a second stage polymerization to form crosslinked thermoset plastics and... 

Where ri > 1 and t2 < 1, the copolymer will always be richer in monomer-1 than in the monomer phase, so that monomer-1 will become depleted in a batch polymerization. The further the reactivity ratios deviate from unity, the greater the deviation between polymer and monomer composition. Systems that exhibit this behavior include methacrylate-acrylate polymerizations, and styrene, methacrylates, or acrylates polymerized with vinyl acetate or ethylene. 

Another factor which can affect the soluble fraction is the relative reactivities of acrylic acid or sodium acrylate with the crosslinkers. As evidenced by reactivity ratios of various monomer pairs, methacrylate esters tend to be more reactive with acrylic acid and acrylate esters less reactive with acrylic acid. In a crosslinking copolymerization therefore, a methacrylate crosslinker will tend to be used up earlier in the reaction than will an acrylate crosslinker. As a result, use of methacrylate crosslinkers tends to give crosslinked polyacrylates with higher extractable fraction. 

ATRP is successfully employed in the polymerization of a large variety of vinyl monomers such as styrenes, methacrylates, acrylates, acrylonitrile, and some others [2,9-15]. However, at present, available catalytic systems seem to be unsuitable for the less reactive monomers such as ethylene, olefines, vinyl chloride, and vinyl acetate. In the polymerization of monomers with strong electron-donating groups such as /7-methoxy styrene, some side reactions arising from the involvement of cationic intermediate are observed. Acrylic and methacrylic acids are also not prone to ATRP because they form Cu(II) carboxylates, which are inefficient deactivators. However, hydroxy derivatives such as hydroxyethyl acrylate and hydroxyethyl methacrylate can be polymerized by ATRP. 

Tetrahydrofurfuryl acrylate and methacrylate reactive unsaturated monomers, are readily polymerized and easily cross-linked by exposure to heat, peroxide catalysts, or uv radiation. 

Methacryhc acid and its ester derivatives are Ctfjy -unsaturated carbonyl compounds and exhibit the reactivity typical of this class of compounds, ie, Michael and Michael-type conjugate addition reactions and a variety of cycloaddition and related reactions. Although less reactive than the corresponding acrylates as the result of the electron-donating effect and the steric hindrance of the a-methyl group, methacrylates readily undergo a wide variety of reactions and are valuable intermediates in many synthetic procedures. 

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