Macromonomers, acrylic-methacrylic

Acrylic Macromonomers. Acrylic-methacrylic macromonomers prepared by catalytic chain transfer using cobalt(II) chelates afford polymer chains, each with an olefinic endgroup (18, 24). Such macromonomers can be polymerized or copolymerized to produce graft polymers that are useful in coatings, fibers, films, and composite materials applications (24). Moreover, one is able to synthesize macromonomers containing several alkylmethacrylates, alkylacrylates, and styrene (IS). 

Block Synthesis. Water-soluble block copolymers are formed from the copolymerization of macromonomers of methacrylates with acrylic and methacrylic acid monomers and their solution properties compared with random copolymers of similar composition (224). Diblock and triblock copolymers may be prepared by a number of techniques and are also used on ink-jet inks (225) and scale inhibition in water boilers (226), respectively. Associative properties of block polymers to form micellar structures are well established (227,228). Triblock polyampholyte polymers are also known (229). 

Suggest a route, via combination of ATRPand CuAAC reaction, foref cient synthesis of polystyrene-fc-poly(w-butyl acrylate)-methacrylate macromonomer, where each block in the copolymer chain has... 

Macromonomer RAFT polymerization is most effective with methacrylate monomers (Table 9.9).With monosubstituted monomers (e.g. S, acrylates) graft copolymerization, is a significant side reaction which can be mitigated but not eliminated by the use of higher reaction temperatures. 

ESI mass spectrometry ive mass spectrometry ESR spectroscopy set EPR spectroscopy ethyl acetate, chain transfer to 295 ethyl acrylate (EA) polymerizalion, transfer constants, to macromonomers 307 ethyl methacrylate (EMA) polymerization combination v.v disproportionation 255, 262 kinetic parameters 219 tacticity, solvent effects 428 thermodynamics 215 ethyl radicals... 

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. 

In our own research, the functional termination of the living siloxanolate with a chlorosilane functional methacrylate leading to siloxane macromonomers with number average molecular weights from 1000 to 20,000 g/mole has been emphasized. Methacrylic and styrenic monomers were then copolymerized with these macromonomers to produce graft copolymers where the styrenic or acrylic monomers comprise the backbone, and the siloxane chains are pendant as grafts as depicted in Scheme 1. Copolymers were prepared with siloxane contents from 5 to 50 weight percent. 

Other efforts based on the macromonomer approach to homopolymers having dendritic side chains, include the work of Draheim and Ritter on acrylate and methacrylate derived structures having dendritic chiral side chains based on L-aspartic esters [17a], and of Xi and coworkers with poly(methacrylate) structures containing very small benzyl ether dendritic side-chains [17b]. Unfortunately, both of these approaches met with limited success due to a significant drop in degree of polymerization (DP) when the size of the dendron used as pendant group in the macromonomers increased from G-l to G-2. 

A second test was done by using butyl acrylate as the comonomer as shown in Figure 11. The reactivity ratios in this case are such that the methacrylate functionality would react slower with acrylates than with vinyl chloride. As predicted the butyl acrylate is at 62% conversion before the MACROMER peak is significantly diminished. These data add validity to the hypothesis that the placement of side chains in the backbone is dependent on the terminal group of the macromonomer and the relative reactivity of its comonomer. 

Sakamoto et al. (2) prepared macromonomers consisting of poly (butyl acrylate-/7-methyl methacrylate), which were used as paint additives to enhance adhesiveness and storage stability properties. 

Poly(methyl methacrylate)-g-poly(dimethylsiloxane) copolymers have been prepared by free radical copolymerizations of acrylate-functional siloxane macromonomers (29) with methyl methacrylate. Siloxane macromonomers (29) of between 1,000 and 20,000 molecular weight were utilized to give a range of copolymers with between 4 and 17 wt% silicone115. 

Poly(ethylene oxide) (PEO) macromonomers constitute a new class of surface active monomers which give, by emulsifier-free emulsion polymerization or copolymerization, stable polymer dispersions and comb-like materials with very interesting properties due to the exceptional properties of ethylene oxide (EO) side chains. They are a basis for a number of various applications which take advantage of the binding properties of PEO [39], its hydrophilic and amphipathic behavior [40], as well as its bio compatibility and non-absorbing character towards proteins [41]. Various types of PEO macromonomers have been proposed and among them the most popular are the acrylates and methacrylates [42]. 

The stable polymer dispersions with small-sized polymer particles of diameter >60 nm were prepared by dispersion copolymerization of PEO-MA macromonomer with styrene, 2-ethylhexyl acrylate, acrylic and methacrylic acids, and butadiene at 60 °C [79]. The particle size was reported to decrease with increasing macromonomer fraction in the comonomer feed. Besides, it varied with the type of the classical monomer as a comonomer. Tg of polymer product was found to be a function of the copolymer composition, the weight ratio macromonomer/monomer, and monomer type and varied from 50.6 to 220.4 °C. 

Copolymerization of PEO Macromonomers with Alkyl Acrylates and Methacrylates... 

End-functionalized polyethylene (PE) [8, 9], polypropylene (PP) [10], and polyisobutylene (PIB) [11] have been transformed to their corresponding macromonomers carrying (meth)acrylate, oxazoline, and methacrylate end groups, 1, 2, and 3, respectively. Polybutadienyl lithium was terminated with chlo-rodimethylsilane, followed by hydrogenation to saturated polyolefin (PHBd) [12]. Hydrosilylation of the end silane with allyl glycidyl ether afforded an epox-... 

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]. 

Narrow distribution in the backbone length as well as in the chemical composition or the branch frequency may be expected from a living-type copolymerization between a macromonomer and a comonomer provided the reactivity ratios are close to unity. This appears to have been accomplished to some extent with anionic copolymerizations with MMA of methacrylate-ended PMMA, 29, and poly(dimethylsiloxane) macromonomers, 30, which were prepared by living GTP and anionic polymerization, respectively [50,51]. Recent application [8] of nitroxide (TEMPO)-mediated living free radical process to copolymerizations of styrene with some macromonomers such as PE-acrylate, la, PEO-methacr-ylate, 27b, polylactide-methacrylate, 28, and poly(e-caprolactone)-methacrylate, 31, may be a promising approach to this end. 

It seems that instead protonated species (anhydride or ester molecules) play a major role in the process. The protons originate from some added acid (e.g. acrylic or methacrylic acid). The characterization of the formed macromonomers revealed that the number of ester functions per molecule is close to 2. The role of the protons is evidenced by the increase of the reaction rate with increasing amount of methacrylic acid in the system. In the absence of a protonic acid high molecular weight poly-THF is produced, no anhydride is consumed and reshuffling does not take place. This mechanism which remains to be confirmed is in any case completely different from the inifer -type cationic transfer which may occur with unsaturated monomers. It is discussed in the next section. 

Yamashita et al.2,99) also investigated the copolymerization of PMMA macromonomers both with a mixture of HEMA and perfluoroalkyl acrylate and with a MMA-methacrylic acid mixture here again, the PMMA grafts originating from the macromonomer play the role of anchoring segments, and surface accumulation of the functional backbone segments is well established. 

To overcome the difficulties of ESI-MS, Simonsick and Prokai added sodium cations to the mobile phase to facilitate ionization [165,166]. To simplify the resulting ESI spectra, the number of components entering the ion source was reduced. Combining SEC with electrospray detection, the elution curves of polyethylene oxides) were calibrated. The chemical composition distribution of acrylic macromonomers was profiled across the molar mass distribution. The analysis of poly(ethylene oxides) by SEC-ESI-MS with respect to chemical composition and oligomer distribution was discussed by Simonsick [167]. In a similar approach aliphatic polyesters [168], phenolic resins [169], methyl methacrylate macromonomers [169] and polysulfides have been analyzed [170]. The detectable mass range for different species, however, was well below 5000 g/mol, indicating that the technique is not really suited for polymer analysis. 

Macromonomers were prepared by polymerizing oxazolines with monofunctional initiators (e.g., methyl p-toluenosulfonate) and terminating the polymerization with salts of acrylic or methacrylic acid. Macromonomers with M varying from M — 500 to —2500 and MJM - 1.2-1.4 were obtained functionalities, however, depended strongly on reaction conditions and the values between 0.99 down to —0.5 and lower were reported [280]. 

Living anionic polymerization of methacrylates and acrylates can be used to prepare macromonomers, which can thereafter be polymerized by any technique known in the state of the art. For instance, Flatada and coworkers reacted anionic ft)-hydroxyl-PMMA (55), which was then polymerized by radical polymerization into the corresponding combshaped copolymer (81) with 2,2 -azobis(isobutyronitrile) (AIBN) as initiator (equation 64). ... 

The 80/20 (wt/wt) methyl methacrylate (MMA) n-butyl acrylate (BA) macromonomer was prepared in the following manner. To a 3000-mL flask 440.1 g MMA, 200.0 g BA, and 150.0 g methyl ethyl ketone (MEK) were added. The mixture was stirred and heated to reflux under a nitrogen blanket. After a 10-min hold, 30.0 g MEK, 0.140 g Vazo-67, and 0.050 g Co(dimethylglyoxime-BF2)2 were added to the flask. After a 5-min hold, 359.9 g MMA, 200.0 g MEK, and 1.90 g Vazo-67 were added over a 3.5-h period. The mixture was held 1 h at reflux after the feed. Subsequently, 150.0 g MEK and 1.00 g Vazo-52 were feed over an hour. The mixture was held for 1 h at reflux. The mixture was then allowed to cool to room temperature. A more detailed procedure and the Co(dimethylglyoxime-BF2)2 synthesis are given in reference 18. 

Using SEC-ESIMS we studied the products of a macromonomer synthesis in which MMA (2) and BA (3) MS were loaded in an 80 20 (wt/wt) weight ratio. The details of the synthesis are reported in Experimental Details. The SEC-ESIMS data will allow us to profile the chemical composition distribution across the MWD. From these data we should be able to measure the relative efficiency of our chain-transfer agent for methacrylates versus acrylates. 

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