Methyl methacrylate styrene block copolymer

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... 

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. 

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. 

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. 

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. 

Figure 9-19. A universal gel-permeation chromatography calibration curve obtained from measurements on linear poly(styrene) (O), comb-branched poly(styrene) (O ), star-branched poly(styrene) ( ), poly(methyl methacrylate) ( ), poly(vinyl chloride) (a) c -l,4-poly-(butadiene) (A), poly(styrene)-poly(methyl methacrylate) block copolymer (Qj ), random copolymer from styrene and methyl methacrylate O), and ladder polymers of poly(phenyl siloxanes) ( ) (according to Z. Grubisic, P. Rempp, and H. Benoit).

For example, methyl methacrylate block copolymers are much less studied than those of styrene. Anion chain transfer occurs at the pendent ester group, drastically reducing the yield of block copolymers. Poly(methyl methacrylate-b-isoprene) has been prepared, however, by using an ingenious chain cap of l,l -diphenylethyl-ene(27,28). i l diphenylethylene will not anionically homopolymerize, therefore it adds only one mer to the macroanion. This anion is more stable in the presence of methyl methacrylate, but will initiate further polymerization. Other workers have reported the preparation of isoprene-methyl methacrylate block copolymers by sequential addition to "living" polyisoprene anions(29,30),... 

Han and Mozer have combined SANS with light scattering to evaluate the configuration of a styrene-methyl methacrylate diblock copolymer when dissolved in toluene. Here again the styrene block was fully deuterated and SANS experiments were made in deuterated toluene thereby providing the radius of gyration of the methyl methacrylate block, since the deuteropolystyrene has essentially zero contrast... 

Styrene-methyl methacrylate diblock copolymers have also been studied in a selective solvent, i.e. a solvent which is thermodynamically better for one or other block. For these experiments, p-xylene was used as the solvent since it had been previously reported as a theta solvent for polymethyl methacrylate at drca 40 °C. Separate SANS measurements were made on a copolymer with a deuterated styrene block dissolved in deuterated xylene and in hydrogenous xylene at tmperatures of 30 °C and 40 °C. Deutero xylene has the same scattering length density as deuterostyrene, consequently the scattered intensity is solely attributable to the methyl methacrylate block when the copolymer is dissolved in this solvent. At the two temperatures used conventional Zimm plots were obtained, however the methyl methacrylate block molecular weight obtained at 30 °C was twice that at 40 °C indicating the formation of a bimolecular multimer at 30 °C. From the radii of gyration obtained at both temperatures it appears that the methyl methacrylate block in the multimer... 

C. Auschra, R. Stadler, and LG. Voigt-Martin, Poly (styrene-b-methyl methacrylate) block copolymers as compatibilizing agents in blends of poly (styrene-co-acrylonitrile) and poly (2, 9-dimethyl-l, 4-phen-ylene ether) 2. Influence of concentration and molecular weight of symmetric block copolymers. Polymer, 34 2094r-2110,1993. 

Figure 18.13 TEM images and models of (a) the knitting pattern kp) and (b) barber pattern hoc) in PS-PEB-PMMA. ((a) Reprinted with permission from H. Ott, V. Abetz and V. Altstadt, Morphological studies of poly(styrene)-block-poly(ethylene-co-butylene)-block-poly(methyl methacrylate) in the composition region of the knitting pattern morphology, Macromolecules, 34, 7, 1069-1075, 2001. 2001 American Chemical Society, (b) Reprinted with permission from U. Krappe, R. Stadler and I. Voigt-Martin, Chiral assembly in amorphous ABC triblock copolymers. Formation of a helical morphology in polystyrene-block-polybutadiene-block-poly(methyl methacrylate) block copolymers, Macromolecules, 28, 13, 4558-4561, 1995. 1995 American Chemical Society.)...

Poly(methyl methacrylate) provides a level of stabilization even though the solution in CCl is below the 0-temperature. All the copolymers, both random and block, are better stabilizers than PMM, the methacrylate units acting as anchors, with stabilizing sequences of styrene loops, of block copolymers, or mixed loops and tails, of random copolymers, at better than 0-conditions. Higher M.W. polystyrenes give silica dispersions too unstable to measure by our optical method the sediment volumes are between those of poly(methyl methacrylate) solutions and pure solvent. 

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). 

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. 

As mentioned above, the ability to have living polymerizations offered the potential to make block copolymers. In the preparation of a block copolymer the sequence of addition can be important to ensure that the second monomer is capable of adding to the living end. An example is the formation of a polystyrene—polymethyl methacrylate block copolymer.38 In this case polystyrene is polymerized first, followed by addition of the methyl methacrylate. The block copolymer could not be formed if methyl methacrylate were polymerized first, as styrene will not add... 

Tureau MS, Epps TH (2009) Nanoscale networks in poly[isoprene-block-styrene-block-(methyl methacrylate)] triblock copolymers. Macromol Rapid Commun 30 1751-1755... 

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

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