Benzyl methacrylate polymerization

In addition to MMA, a variety of methacrylic esters were polymerized rapidly to the corresponding polymers with narrow MWDs in the presence of methylaluminum bis(2-ferf-butyl-4-methoxyphenolate) (3c). The successful examples include ethyl methacrylate (EMA), isopropyl methacrylate ( °PMA), n-butyl methacrylate ("BMA), isobutyl methacrylate ( °BMA), benzyl methacrylate (BnMA), and dodecyl methacrylate (Cj2MA), where the Mn values were all close to the predicted values (Mn j ) with the Mw/Mn ratios below 1.1 (Table 3, runs 1-4,6,7). The polymerization of ferf-butyl methacrylate ( BMA) is the only exception, where the monomer conversion hardly increased even after 24 h. 

Some of the polymers slowly change their helicity in solution. A chiral crown ether-potassium ferf-butoxide combined system was reported to cause polymerization of methyl, tert-butyl, and benzyl methacrylate to form isotactic polymers that had high rotation values (164). Detailed scrutiny, however, raised questions about the result (135, 165). At first, in the presence of the initiator, the oligomers exhibit considerable activity, but after removal of the catalyst, the optical activity decreases. This decrease may be attributed to unwinding of the helixes in the chain the helicity could be caused by the anchored catalyst. 

The tacticity has been estimated by N. M. R. analysis also in the case of poly - (1 - methyl-benzyl) -methacrylate (64) obtained by different polymerization processes (Table 18). 

The experimental data obtained by several authors who polymerized, by radical processes, optically active para-sec.butyl-vinyl benzoate (73), ortho-vinyl-benzyl-sec.butylsulfide (98), 1.3-dimethyl-butyl-methacrylate (9), and (l-methyl-benzyl)-methacrylate (14), confirmed the theoretical forecast. In fact the polymers obtained after cleavage of the optically active groups did not show optical activity. The stereoregularity of the polymers has not been carefully checked up and the possible increase in stereoregularity, which was theoretically foreseen, has not been reported. 

Helix-sense-selective polymerization of methyl, benzyl, and f-butyl methacrylates was attempted by using the complexes of chiral crown ethers, 91 and 92, and that of a chiral diamine 93 with n-BuLi however, these esters seem to be too small to form and maintain helical conformation [138,139], The complexes of BuLi with 58a and 59 failed in producing an optically active, helical polymer in the polymerization of methyl and benzyl methacrylates [104b]. 

A multi-MIP array has been fabricated photolithographic ally for determination of an albuterol broncholidator (Table 6) [185]. 20-pm diameter acrylic MIP beads have been synthesized by co-polymerization of the benzyl methacrylate functional monomer, MAA functional monomer and HEMA cross-linker in the propylene glycol monomethyl ether acetate porogenic solvent. Thermo-radical polymerization on a Pt electrode was initiated by AIBN. Albuterol was recognized in the... 

AA acac alt AIBN Ar Bd Bu BuA BuMA BzMA CMSty CR CT CTFE DBP DPn EA HEA HEMA HFP acrylamide acetylacetonate alternating azobisisobutyronitrile aromatic group butadiene n-butyl n-butyl acrylate n-butyl methacrylate benzyl methacrylate chloromethyl styrene counter-radical transfer constant chlorotrifluoroethylene dibenzoyl peroxide average degree of polymerization in number ethyl acrylate 2-hydroxyethyl acrylate 2-hydroxyethyl methacrylate hexafluoropropene... 

Various methacrylic-styrene copolymers were prepared in which the reactivity of methacrylate monomers used in the first step decreases in the order MM A > BuMA > benzyl methacrylate. For instance, the bulk polymerization of MMA with such an aromatic azo compound proceeds via a living radical mechanism and the sterically crowded C-C(C6H5)3 terminal bond of polymethacrylate 37 can be cleaved thermally to produce a,co-diaromatic PMMA-h-PS block copolymers in 48-72% yield. 

Examples of homopolymers are given. Poly(4-vinylphenol) was prepared as a prepolymer for the subsequent alkylation [55]. Poly[2-(4-vinylbenzyl)hydroqui-none] 65 is an example of the unhindered phenolic antioxidant for rubbers. Many homopolymers bear a hindered phenolic moiety. Homopolymer 66 was proposed for blending with BR and IR [56]. Other examples are poly[vinyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] [57] (67), poly(3,5-di-/ert-butyl-4-hydroxy-benzyl methacrylate) [58] (68) or poly[iV-3,5-di-tert-butyl-4-hydroxybenzyl) male-imide] [59] (69). Numerous polymeric antioxidants are functionalized with aromatic amine groups. Poly(4-anilinophenyi methacrylate) [53] (70) serves as an example. 

Cp2TiCl2 has been assessed as additive that controls polymer chain growth in the polymerization of methyl methacrylate.1224 Methyl methacrylate is easily polymerized in the photopolymerization with Cp2TiCl2 in a water-methanol mixture under irradiation of a 15 W fluorescent room lamp. The polymerization proceeded heterogeneously.1225 This process in the presence of 2,2 -bipyridyl, 1,10-phenanthroline, or sparteine as the chelating reagent has been studied.1226 Similar studies on the polymerization of methacrylate monomers such as methyl methacrylate, ethyl methacrylate, phenyl methacrylate, and benzyl methacrylate at 40 °C have also been performed.1227 The results of co-polymerization of methyl methacrylate and acrylonitrile indicate that this process proceeds through a radical mechanism.1228 The mechanism of the controlled radical polymerization of styrene and methyl methacrylate in the... 

Silica microspheres ( 3 /tm) with initiating moiety (S-8) induced the copper-catalyzed radical polymerization of benzyl methacrylate to form polymer layers on the surface.459 The thickness of polymer shell can be increased to 550—600 nm, where the Mn and MWDs of the arm polymers were 26500 and 1.26, respectively. Removal of the core silica by chemical etching gave uniform hollow polymer microspheres. 

Stereoselective polymerizations and copolymerizations of methacrylates have also been realized recently and are potentially of considerable importance. In the case of (RS)-a-methylbenzyl methacrylate with anionic catalysts and 2,3-epoxypropyl methacrylate with an optically active Grignard catalyst selective propagations appear to occur. Copolymerization of (RS)-a-methyl-benzyl methacrylate and methyl methacrylate also proceed stereoselectively. ... 

Polymerization of benzyl methacrylate (BMA) is much slower than that of BA. Although the yield of the polymer increased with an increase in the residence time, the polymerization did not complete within 12 min. The value of M /Mn was much smaller than that for BA, both in the microflow system and the macrobatch system. The effect of the microflow system on molecular-weight distribution control is, however, smaller than for the BA case. Probably, temperature control for BMA polymerization is better than that for BA polymerization, even in the macrobatch system, because heat generation per unit time for BMA polymerization seems to be much less than that for BA polymerization. 

Schulz et al.12,13 estimated the elementary rate constants for methyl methacrylate in solvents whose viscosities varied by a factor of 170, indicating that the termination rate constants were inversely proportional to the viscosity of the solvents. The variation of propagation rate constants was much less than that of termination rate constants. They have also obtained similar results in the free radical polymerization of benzyl methacrylate. 

Composite latex particles of poly(n-butyl acrylate) ly(benzyl methacrylate) (PBA/PBM) [67] prepared by semi-continuous seeded onulsion polymerization in the presence of a chain transfer agent (isooctyl mercrptoproprionate) (lOMP) exhibited a hemispherical morphology or else laiger domains of PBM were... 

Electron-withdrawing substituents in anionic polymerizations enhance electron density at the double bonds or stabilize the carbanions by resonance. Anionic copolymerizations in many respects behave similarly to the cationic ones. For some comonomer pairs steric effects give rise to a tendency to altemate. The reactivities of the monomers in copolymerizations and the compositions of the resultant copolymers are subject to solvent polarity and to the effects of the counterions. The two, just as in cationic polymerizations, cannot be considered independently from each other. This, again, is due to the tightness of the ion pairs and to the amount of solvation. Furthermore, only monomers that possess similar polarity can be copolymerized by an anionic mechanism. Thus, for instance, styrene derivatives copolymerize with each other. Styrene, however, is unable to add to a methyl methacrylate anion, though it copolymerizes with butadiene and isoprene. In copolymerizations initiated by w-butyllithium in toluene and in tetrahydrofuran at-78 °C, the following order of reactivity with methyl methacrylate anions was observed. In toluene the order is diphenylmethyl methacrylate > benzyl methacrylate > methyl methacrylate > ethyl methacrylate > a-methylbenzyl methacrylate > isopropyl methacrylate > t-butyl methacrylate > trityl methacrylate > a,a -dimethyl-benzyl methacrylate. In tetrahydrofuran the order changes to trityl methacrylate > benzyl methacrylate > methyl methacrylate > diphenylmethyl methacrylate > ethyl methacrylate > a-methylbenzyl methacrylate > isopropyl methacrylate > a,a -dimethylbenzyl methacrylate > t-butyl methacrylate. 

Benzyl methacrylate (BzMA) monomer was chosen as monomer for the polymerization followed in-situ by NMR. Monomer conversion is easily measured by integration of the vinyl resonances (6-5 ppm) relative to the combined values of the CH2 a to OC-O, moved by the presence of the aromatic ring, from the monomer and polymer (5.10 ppm), figure 13. 

Polymerizations of benzyl methacrylate (BzMA) were carried out in a toluene- /g solution with (i) a PEG-based macroinitiator, MeOPEG-lin, and (ii) ethylene glycol diethyl ether as co-solvent. According to the previous study, the reaction temperature was kept at 50°C in order to keep control over the polymerization. 

Figure 14. First order kinetic plots for the polymerization of benzyl methacrylate (BzMA) in toluene-(is at 50°C (O), in toluene using, MeO(PEG)-I 13 (M = 5000 g/mol ), and in toluene-afx / diethyl ether ethylene glycol (4/1 g/g ).

In the same year, Iwasaki etol. [17] described the effect of a micro-reactor on the free radical polymerization of butyl acrylate, benzyl methacrylate, methyl methacrylate, vinyl benzoate, and styrene. In this case, the reactor system was a simple T-shaped mixing unit, followed by a polymerization section (the latter was responsible for an extended residence time). The total residence times were on the order of 0.5-10 min. In the T-shaped mixing section, the two liquids - one a neat monomer, the other toluene containing 0.03-0.05 mol 1 AIBN as initiator - were combined with the same flow rate. The decay of AIBN in the system was monitored initially at different temperatures, to verify that sufficient initiator was present for complete conversion under all reaction conditions. 

Figure 20-2. Dependence of the rate constant for polymerization termination by mutual deactivation of two polymer free radicals on the viscosity of the solvent for styrene (STY), methyl methacrylate (MMA), benzyl methacrylate (BMA) polymerizations at 2(fC. (After G. V. Schulz.)...

The groups of Kramer and Hawker provided an example where the target polymer could be made using sequential CFR polymerizations, but CuAAC simplified the process and made it possible to obtain the polymer with a precise molecular weight and a low polydispersity index (PDl). Attempts to make poly(benzyl methacrylate)-b-poly(butyl acrylate) with equal volume fractions of each block to be used for the determination of order-disorder transition (ODT) led to materials with imprecise volume fractions and PDls higher than 1.3. Instead, by using preformed homopolymers that were then coupled by CuAAC, the authors were able to make a small library of covalent diblock copolymers with low PDIs, while also performing fewer total reactions. 

Triblock copolymers can be synthesized by either the difiinc-tional initiator or the sequential monomer addition routes under ambient conditions such as room temperature polymerization conditions. Poly(benzyl methacrylate)-27-poly(lauryl methacrylate)- 7-poly(benzyl methacrylate) (PBzMA-PLMA-PBzMA) was synthesized using l,5-bis(trimethylsi-loxy)-1,5-dimethoxy-2,4-dimethyl- 1,4-pentadiene (BDDB)... 

For butyl acrylate (BA), the molecular weight distribution was found to be narrower than that for the batch reactor, as can be seen in Figure 12.5. The PDI for this polymer is then lower in the microreactor system (Table 12.1). The difference was smaller but still noticeable for benzyl methacrylate (BMA) and methyl methacrylate (MMA) and almost zero for vinyl benzoate (VBz) and styrene (St) (Table 12.2). The authors claimed that the observed results are directly related to the superior heat transfer ability of the microtube reactor. The more exothermic the polymerization reaction. 

Controlled structure PMAA can be prepared by the deprotection of an appropriate precursor polymethacrylate which has itself been polymerized under living conditions. Both anionic polymerization and GTP have been used to prepare PMAA employing a variety of PMAA precursor monomers such as benzyl methacrylate (125), ter -butyl methacrylate (126), trimethylsilyl methacrylate (127) and 2-tetrahydropyranyl methacrylate (128,129). Removal of the protecting group yields the desired PMMA. 

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