Styrene-methyl methacrylate, block

Thus, the synthesis of a styrene-methyl methacrylate block polymer requires that styrene be the first monomer. Further, it is useful to decrease the nucleophilicity of polystyryl carbanions by adding a small amount of 1,1-diphenylethene to minimize attack at the ester function of MMA [Quirk et al., 2000]. Block copolymers of styrene with isoprene or 1,3-butadiene require no specific sequencing since crossover occurs either way. Block copolymers of MMA with isoprene or 1,3-butadiene require that the diene be the first monomer. The length of each segment in a block copolymer is controlled by the ratio of each monomer to initiator. The properties of the block copolymer vary with the block lengths of the different monomers. 

The GPC analysis of block copolymers is handicapped by the difficulty in obtaining a calibration curve. A method has recently been suggested to circumvent this difficulty by using the calibration curves of homopolymers. This method has been extended so that the calibration curves of block copolymers of various compositions can be constructed from the calibration curve of one-component homopolymers and Mark-Houwink parameters. The intrinsic viscosity data on styrene-butadiene and styrene-methyl methacrylate block polymers were used for verification. The average molecular weight determined by this method is in excellent agreement with osmometry data while the molecular weight distribution is considerably narrower than what is implied by the polydispersity index calculated from the GPC curve in the customary manner. 

Kim HC, Nam KH, Jo WH. The effect of a styrene-methyl methacrylate block copolymer on the morphological, rheological and mechanical properties of poly(2-6-dimethyl-l,4-phenylene ether) (PPE) and poly(hydroxyether of bis-phenol A) (phenoxy) blends. Polymer 1993 34 4043-4051. 

SMMA styrene-methyl methacrylate block copolymer... 

KRA Krause, S., Dilute solution properties of a styrene-methyl methacrylate block... 

KOT Kotaka, T., Ohnuma, H., and Inagaki, H., Thermodynamic and conformational properties of styrene-methyl methacrylate block copolymers in dilute solution. 11-Behavior in theta solvents. Polymer, 10, 517, 1969. 

Figure 6.20. Segment distributions of a styrene-(methyl methacrylate) block copolymer (relative molecular masses of each block were in the range 48 000-65 000) at an interface between polystyrene (relative molecular mass in the range 110000-127 000) and poly(methyl methacrylate) (relative molecular mass in the range 107000-146 000), revealed by a series of neutron reflection experiments in which various parts of the copolymer and/or one of the homopolymers was labelled with deuterium. The bold lines are the segment density profiles for all styrene and methyl methacrylate segments, summed over both the homopolymer and the copolymer the solid lines are the homopolymers, and the dotted lines are the styrene and methyl methacrylate blocks of the copolymer. After Russell et al. (1991).

Surface-induced ordering in a block copolymer that is disordered in the bulk has been detected using neutron reflectometry for styrene/methyl methacrylate block copolymers, in which the styrene block is favoured at the surface and the methacrylate block is favoured at a silicon oxide substrate (Anastasiadis et al. 1989a, b). Figure 6.29 shows how the decay length characterising the oscilla-... 

Figure 7.4. Fracture energies of interfaces reinforced by block copolymers as a function of the effective areal density of chains crossing the interface. Triangles and squares are for polystyrene/poly(2-vinyl pyridine) interfaces reinforced with styrene-2-vinyl pyridine block copolymers (Creton et al. 1992) circles are for poly(xylenyl etherypoly(methyl methacrylate) interfaces reinforced with styrene-methyl methacrylate block copolymers (Brown 1991a, b). After Creton et al. (1992).

Figure 5.14 Three-dimensional presentation of molecular mass distribution and chemical composition distribution for a poly(styrene-methyl methacrylate) block copolymer [72].

SMMA Styrene-methyl methacrylate block copolymer TEM Transmission electron microscopy THE Tetrahydrofuran... 

SMMA Styrene-methyl methacrylate block copolymer sPS Syndiotactic polystyrene S-S Simha and Somcynsky cell-hole theory SSE Single-screw extmder SSSE Solid-state shear extrusion TD Transverse direction TEM Transmission electron microscopy Tg Glass transition temperature THE Tetrahydrofuran TIBA fr -Isobutyl aluminum (°C) Melting temperature TMA fr -Methyl aluminum TMS Trimethylsilyl... 

Rharbi, Y. and Winnik, M.A. (2001) Interface thickness of a styrene-methyl methacrylate block copolymer in the lamella phase by direct norrradiative energy... 

W.H. Jo, H.C. Kim, and D.H. Baik, Compatibilizing effect of a styrene-methyl methacrylate block copolymer on the phase behavior of poly (2, 6-dimethyl-l,4-phenylene oxide) and poly (styrene-co-acrylonitri-le) blends. Macromolecules, 24(9) 2231-2235, April 1991. 

The reaction of AIBN with formaldehyde leads to units, styrene, and methyl methacrylate blocks were ob-... 

Yagci and Deniziigil [44] applied the method of partial decomposition of MAIs introducing styrene and methyl methacrylate blocks into poly(amide)s. The poly-(amide)-based MAI had been prepared by a reaction of AIBN with formaldehyde (see Scheme 10). Evidently, since each unit of the preformed MAI carries one azo group, there are enough azo sites in every MAI molecule for a controlled and adjustable partial decomposition. 

There are some indications that the situation described above has been realized, at least partially, in the system styrene-methyl methacrylate polymerized by metallic lithium.29 29b It is known51 that in a 50-50 mixture of styrene and methyl methacrylate radical polymerization yields a product of approximately the same composition as the feed. On the other hand, a product containing only a few per cent of styrene is formed in a polymerization proceeding by an anionic mechanism. Since the polymer obtained in the 50-50 mixture of styrene and methyl methacrylate polymerized with metallic lithium had apparently an intermediate composition, it has been suggested that this is a block polymer obtained in a reaction discussed above. Further evidence favoring this mechanism is provided by the fact that under identical conditions only pure poly-methyl methacrylate is formed if the polymerization is initiated by butyl lithium and not by lithium dispersion. This proves that incorporation of styrene is due to a different initiation and not propagation. 

Various substituted styrene-alkyl methacrylate block copolymers and all-acrylic block copolymers have been synthesized in a controlled fashion demonstrating predictable molecular weight and narrow molecular weight distributions. Table I depicts various poly (t-butylstyrene)-b-poly(t-butyl methacrylate) (PTBS-PTBMA) and poly(methyl methacrylate)-b-poly(t-butyl methacrylate) (PMMA-PTBMA) samples. In addition, all-acrylic block copolymers based on poly(2-ethylhexyl methacrylate)-b-poly(t-butyl methacrylate) have been recently synthesized and offer many unique possibilities due to the low glass transition temperature of PEHMA. In most cases, a range of 5-25 wt.% of alkyl methacrylate was incorporated into the block copolymer. This composition not only facilitated solubility during subsequent hydrolysis but also limited the maximum level of derived ionic functionality. 

IR analysis shows that double bonds were absent in the product within the range of an experimental error. The reaction product is composed of ladder blocks and the blocks of styrene units. In order to verify this structure, hydrolysis of the product was carried out in methanol-benzene and methanol solutions of KOH. After the hydrolysis, the product was esterified by diazomethane and styrene-methyl methacrylate copolymer was separated. The expected scheme of these reactions is as follows ... 

NMR study shows that the block copolymer of styrene-methyl methacrylate is present in the product of esterification. It confirms that the original copolymer consists of blocks of styrene units and the ladder type blocks. Analysis of a few fractions of the copolymer obtained from oligomeric multimonomer and styrene confirmed this type of structure. Data recalculated from publications are presented in Table 5.1. 

In another recent example, dtrate-capped Au NPs are modified with 1-dodeca-nethiol in a first step. These premade nanoparticles were encapsulated with block copolymers such as poly(styrene-block-acrylic acid) (PS-b-PAA) and poly(methyl-methacrylate-block-acrylic acid) (PMMA-b-PAA) leading to core-shell hybrid materials. The Au NP diameters are 12 and 31 nm with average shell thickness of about 15 nm [121] (Scheme 3.18). 

Applying this method to the system polystyrene/methyl methacrylate, block copolymers containing 20—30% styrene have been prepared the systems polyvinyl acetate/styrene and polyvinyl acetate/ethyl chloroacrylate afford block copolymers containing respectively 40 and 82% vinyl acetate 204). In contrast, the polystyrene prepared using phthalyl polyperoxide was unable to initiate the polymerization of vinyl acetate or vinylpyrrolidone, likely on account of the difference in stability of the concerned radicals. 

The infrared spectograms were obtained on a Beckman IR-10 instrument. Solutions of the styrene-maleic anhydride alternating copolymer and styrene block copolymer were used. A KBr pellet was used for the spectogram of the methyl methacrylate block copolymer. 

Instead of adding more styrene to the polymerization above, what if we were to add a second monomer say methyl methacrylate, after the first monomer had been totally consumed The result would be an AB block copolymer. Aw represents the first monomer, styrene in our example, and B the methyl methacrylate. The degrees of polymerization of the two blocks could be the same, or they could be different. The steps involved in constructing the methyl methacrylate block are shown in the following scheme ... 

The reactions are just like the ones that produce polystyrene. First, a molecule of methyl methacrylate reacts with a polystyryl anion to form a methyl methacrylate anion (crossover). Then the methyl methacrylate block grows in a series of propagation steps, followed by the addition of methanol to effect termination as before. We can draw the structure for the block copolymer, named poly styrene-6/oe -methyl methacrylate) as is shown here. 

Homopolymerization of a vinylic monomer (styrene, methyl methacrylate) in the presence of polysulphide yields a block copolymer [39]... 

The styrene/methyl methacrylate pair contains monomers with different relative reactivity levels in Table 9-1. Polystyryl anion will initiate the polymerization of methyl methacrylate, but the anion of the latter monomer is not sufficiently nucleophilic to cross-initiate the polymerization of styrene. Thus the anionic polymerization of a mixture of the two monomers yields polyfmethyl methacrylate) while addition of methyl methacrylate to living polystyrene produces a block copolymer of the two monomers. 

New macroradicals have been obtained by proper solvent selection for the homopolymerization of styrene, methyl methacrylate, ethyl acrylate, acrylonitrile, and vinyl acetate, and by the copolymerization of maleic anhydride with vinyl acetate, vinyl isobutyl ether, or methyl methacrylate. These macroradicals and those prepared by the addition to them of other monomers were stable provided they were insoluble in the solvent. Since it does not add to maleic anhydride chain ends, acrylonitrile formed a block copolymer with only half of the styrene-maleic anhydride macroradicals. However, this monomer gave excellent yields of block polymer when it was added to a macroradical obtained by the addition of limited quantities of styrene to the original macroradical. Because of poor diffusion, styrene did not add to acrylonitrile macroradicals, but block copolymers formed when an equimolar mixture of styrene and maleic anhydride was added. 

Structure and Properties of Random, Alternating, and Block Copolymers The UV Spectra of Styrene-Methyl Methacrylate Copolymers... 

Zyler (Novacor, USA) Styrene methyl methacrylate copolymer/ elastomer block copolymer, SMMA/SBS Resistant to alcohol... 

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