Vinyl methacrylate anionic copolymerization

Radical copolymerization is used in the manufacturing of random copolymers of acrylamide with vinyl monomers. Anionic copolymers are obtained by copolymerization of acrylamide with acrylic, methacrylic, maleic, fu-maric, styrenesulfonic, 2-acrylamide-2-methylpro-panesulfonic acids and its salts, etc., as well as by hydrolysis and sulfomethylation of polyacrylamide Cationic copolymers are obtained by copolymerization of acrylamide with jV-dialkylaminoalkyl acrylates and methacrylates, l,2-dimethyl-5-vinylpyridinum sulfate, etc. or by postreactions of polyacrylamide (the Mannich reaction and Hofmann degradation). Nonionic copolymers are obtained by copolymerization of acrylamide with acrylates, methacrylates, styrene derivatives, acrylonitrile, etc. Copolymerization methods are the same as the polymerization of acrylamide. 

The reactivity of monomers with electron-releasing substituents in anionic copolymerization is nil. Correlation of reactivity in copolymerization with structure has been achieved in some studies [Favier et al., 1977 Shima et al., 1962]. The reactivities of various substituted styrenes and methacrylates in anionic polymerization, as well as the reactivities of various vinyl... 

Many monomers respond to a specific class of initiator or initiating mechanism with the exclusion of all others. Isobutylene polymerizes only cationically, not anionically or free radically. It is highly probable, therefore, that an initiator that induces polymerization in isobutylene acts cationically. Acrylates and methyl methacrylate do not polymerize cationically, but free radically or anionically. Cyclic sulfides and oxides do not undergo a free radical polymerization. Alternatively, monomers can also be used to test an initiator, if different initiators lead to completely different polymer structures. 2-Vinyloxyethyl methacrylate is polymerized cationically be means of the vinyl group, anionically via the acrylic group, and free radically via both groups (cross-linked polymers). Another possibility consists of the copolymerization of two different monomers (see Chapter 22). Suitable pairs are shown in Table 15-4. 

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). 

Recently it has been shown that anionic functionalization techniques can be applied to the synthesis of macromonomers — macromolecular monomers — i.e. linear polymers fitted at chain end with a polymerizable unsaturation, most commonly styrene or methacrylic ester 69 71). These species in turn provide easy access to graft copolymers upon radical copolymerization with vinylic or acrylic monomers. 

Penultimate effects have been observed for many comonomer pairs. Among these are the radical copolymerizations of styrene-fumaronitrile, styrene-diethyl fumarate, ethyl methacrylate-styrene, methyl methacrylate l-vinylpyridine, methyl acrylate-1,3-butadiene, methyl methacrylate-methyl acrylate, styrene-dimethyl itaconate, hexafluoroisobutylene-vinyl acetate, 2,4-dicyano-l-butene-isoprene, and other comonomer pairs [Barb, 1953 Brown and Fujimori, 1987 Buback et al., 2001 Burke et al., 1994a,b, 1995 Cowie et al., 1990 Davis et al., 1990 Fordyce and Ham, 1951 Fukuda et al., 2002 Guyot and Guillot, 1967 Hecht and Ojha, 1969 Hill et al., 1982, 1985 Ma et al., 2001 Motoc et al., 1978 Natansohn et al., 1978 Prementine and Tirrell, 1987 Rounsefell and Pittman, 1979 Van Der Meer et al., 1979 Wu et al., 1990 Yee et al., 2001 Zetterlund et al., 2002]. Although ionic copolymerizations have not been as extensively studied, penultimate effects have been found in some cases. Thus in the anionic polymerization of styrene t-vinylpyri-dine, 4-vinylpyridine adds faster to chains ending in 4-vinylpyridine if the penultimate unit is styrene [Lee et al., 1963]. 

To the first category belong the homo- and copolymerization of macromonomers. For this purpose, macromolecules with only one polymerizable end group are needed. Such macromonomers are made, for example, by anionic polymerization where the reactive chain end is modified with a reactive vinyl monomer. Also methacrylic acid esters of long-chain aliphatic alcohols or monofunctional polyethylene oxides or polytetrahydrofurane belong to the class of macromonomers. 

Q = 1.4 and e = 0.46 were determined from the results of the copolymerization of the complex monomer 26 with methacrylic acid. The reactivity of the MA anion (Q = 0.9, e = —1.0) was affected by coordination to the Co(III) complex. In other words coordination, decreased the electron density of the vinyl group. 

One of the first detailed studies on these systems was that of Beaman (26), who showed that methacrylonitrile polymerizes by an anionic chain mechanism when treated with various bases, including Na in liquid ammonia at —75° C. He noted also that low molecular weight polymers are obtained from reaction of acrylonitrile with butylmagnesium bromide. Foster (56) extended the liquid ammonia method to copolymerization studies in which acrylonitrile was combined with styrene, with methyl methacrylate and with vinyl butyl sulfone. Satisfactory data were obtained only with the sulfone, in which case there was some tendency for alternation. 

Pentadienyl-terminated poly(methyl methacrylate) (PMMA) as well as PSt, 12, have been prepared by radical polymerization via addition-fragmentation chain transfer mechanism, and radically copolymerized with St and MMA, respectively, to give PSt-g-PMMA and PMMA-g-PSt [17, 18]. Metal-free anionic polymerization of tert-butyl acrylate (TBA) initiated with a carbanion from diethyl 2-vinyloxyethylmalonate produced vinyl ether-functionalized PTBA macromonomer, 13 [19]. 

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. ... 

Recent investigations [259] have indicated that the polymerization is not conventional free radical in character but is likely to be coordinated anionic. In support of this view are the reactivity ratio coefficients in copolymerization of vinyl chloride with vinyl acetate and methyl methacrylate, which are different from those found with free radical initiators. 

In later work it was shown that water-soluble antennas could be made by copolymerizing aa oinatic monomers such as vinyl naphthalene and naphthylmethyl methacrylate with polyelectrolytes such as acrylic acid [3,4]. The high efficiency of these antennas in dilute aqueous base was attributed to the hypercoiling of the poly-(acrylic acid) chain to give a pseudo micellar stincture such as that illustrated schematically in Figure 2. We believe that such structures are formed spontaneously in solution due to the hydro-phobic interactions of the large aromatic ccmiponents stabilized by the interaction of water with the hydrophillic carboxyl anions. 

Consider the copolymerization of 1,3-butadiene with the following monomers n-butyl vinyl ether, methyl methacrylate, methyl acrylate, styrene, vinyl acetate, acrylonitrile, maleic anhydride. If the copolymerizations were carried out using cationic initiation, what would be expected qualitatively for the copolymer compositions List the copolymers in order of their increasing butadiene content. Would copolymers be formed from each of the comonomer pairs Explain what would be observed if one used anionic initiation ... 

Since the first preparation of stereoregular poly(methyl methacrylate) by Fox et al. and Miller et al. in 1958, a large number of papers have been published on the steieospecific polymerization of methyl methacrylate, while the NMR technique for the determination of microstructure developed by Bovey and Tiers and Nishioka et al. enabled us to accumulate the extensive information on this polymerization. Mostly anionic initiators have been used for the pdymerization. A review on the polymerization by lithium compounds was presented by Bywater In a recent review by Pino and Suter were discussed some of the factors which can influence the stereoregulation in the polymerization of vinyl monomers including a-substituted acrylate. A variety of magnesium and aluminum compounds can be utilized as stereospecific initiators. Besides methyl methacrylate, not only methacrylates with various ester groups, but also a-substituted acrylates, such as a-ethyl- or o-phenyl-acrylate, were also subjected to the stereospecific polymerization by anionic initiator. The stereospecificity in the copolymerization between the monomers described above is also a matter of interest. 

VFc has been copolymerized with common monomers such as styrene [19], methyl methacrylate [19], N-vinylpyrollidone [20], and acrylo nitrile [19]. The electron richness of VFc has been demonstrated in its copolymerization with maleic anhydride, in which an alternating composition of the copolymer was observed over a wide range of feed ratios [16, 19]. The Q and e values of VFc were determined. The value of e = -2.1 again emphasizes the electron rich nature of the vinyl group of VFc [21]. Therefore it looked rather hopeless to apply anionic initiators for the polymerization of VFc. 

Similarly to the poly(acrylamide)s and poly(vinyl amide)s, POEGMA can be prepared by free radical polymerization, CRP and anionic polymerization, whereby the latter two methods result in well-defined polymer structures with defined end-groups. Even though CRP of OEGMA can be performed by ATRP and RAFT polymerization (Becer et al, 2008 Lutz and Hoth, 2006a), the methacrylate obstructs OEGMA homopolymeriza-tion by nitroxide mediated polymerization. This can, however, be overcome by copolymerization with a minor amount of styrenic comonomer that enables good control over the polymerization (Charleux et al., 2005 Lessard et al., 2012). 

---