Styrene/methyl methacrylate separation

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 ... 

Xie et al. (92, 93) synthesized simultaneous IPN from castor oil polyurethane and copolymers of vinyl monomers, including styrene, methyl methacrylate, and acrylonitrile, without cross-linker using a redox initiator at room temperature and both the formation kinetics of cross-linking and grafting on phase separation were examined. It was demonstrated that the resulting materials were mainly grafted IPN... 

New copolymer membranes of acrylonitrile for the separation of benzene-CYH mixtures by PV were developed by Ray et al. (1997). The monomers in the copolymers were selected on the basis of their solubility parameter values relative to those of benzene and CYH. These were styrene, methyl methacrylate, and vinyl acetate. Copolymers of acrylonitrile with methyl methacrylate and vinyl acetate showed good selectivity and moderate flux 60-70 and 0.075 kg/m h, respectively, with a membrane of 10 pm thickness for a feed mixture containing 5% benzene. Copolymer of acrylonitrile with styrene showed comparatively higher flux but lower selectivity. Ray et al. claimed that the selectivities obtained with these membranes were better than those reported in the literature. 

Sato et al. [752] did a similar study on poly(styrene/methyl methacrylate) copolymer (PMMA). A 100/0-> 60/40 acetonitrile/DCM gradient was used with a polystyrene column. As pore size decreased, significant band broadening occurred as the retention mechanism became less dominated by adsorption while size exclusion began to play an equally important role in the separation process. 

Glockner et al. [815] examined this balance in the characterization of styrene/ ethyl and styrene/methyl methacrylates (SEM and SMM, respectively) on a Cjg column (A = 260 run). In these separations a step gradient was used fi om 100% acetonitrile to 20-50% THF at 0.01 min follow by a 10-min gradient to 50% heptane (with the percent acetonitrile decreasing inversely to the heptane). A 5-20 pg of sample was injected for each run. Excellent resolution of 32%, 55%, and 68% ethyl methacrylate co-polymers was achieved in 8 min. 

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... 

TLC has been used in the study of many homopolymers polystyrene, poly(methyl methacrylate), poly(ethylene oxide), polyisoprene, poly(vinyl acetate), poly(vinyl chloride) and polybutadiene. Their molecular weight, molecular-weight distributions, microstructure (stereo-regularity, isomerism and the content of polar end groups), isotope composition and branching have been studied. For copolymer characterisation (e.g. purity and compositional inhomogeneity), random copolymers such as styrene-methacrylate, and block copolymers such as styrene-butadiene, styrene-methyl methacrylate and styrene-ethylene oxide have been separated. A good review article on polymers... 

Acryhc stmctural adhesives have been modified by elastomers in order to obtain a phase-separated, toughened system. A significant contribution in this technology has been made in which acryhc adhesives were modified by the addition of chlorosulfonated polyethylene to obtain a phase-separated stmctural adhesive (11). Such adhesives also contain methyl methacrylate, glacial methacrylic acid, and cross-linkers such as ethylene glycol dimethacrylate [97-90-5]. The polymerization initiation system, which includes cumene hydroperoxide, N,1S7-dimethyl- -toluidine, and saccharin, can be apphed to the adherend surface as a primer, or it can be formulated as the second part of a two-part adhesive. Modification of cyanoacrylates using elastomers has also been attempted copolymers of acrylonitrile, butadiene, and styrene ethylene copolymers with methylacrylate or copolymers of methacrylates with butadiene and styrene have been used. However, because of the extreme reactivity of the monomer, modification of cyanoacrylate adhesives is very difficult and material purity is essential in order to be able to modify the cyanoacrylate without causing premature reaction. 

When the polymer was prepared by the suspension polymerization technique, the product was crosslinked beads of unusually uniform size (see Fig. 16 for SEM picture of the beads) with hydrophobic surface characteristics. This shows that cardanyl acrylate/methacry-late can be used as comonomers-cum-cross-linking agents in vinyl polymerizations. This further gives rise to more opportunities to prepare polymer supports for synthesis particularly for experiments in solid-state peptide synthesis. Polymer supports based on activated acrylates have recently been reported to be useful in supported organic reactions, metal ion separation, etc. [198,199]. Copolymers are expected to give better performance and, hence, coplymers of CA and CM A with methyl methacrylate (MMA), styrene (St), and acrylonitrile (AN) were prepared and characterized [196,197]. 

FIGURE 20.10 (a,b) Phase images of cryo-ultramicrotomed surfaces of triblock copolymer styrene and ethylene-butylene (SEES) samples of neat material and loaded with oil (40 wt%), respectively. (c,d) Phase images of film of triblock copolymer poly(methyl methacrylate-polyisobutylene-poly(methyl methacrylate) (PMMA-PIB-PMMA) immediately after spin-casting and after 3 h annealing at 100°C, respectively. Inserts in the top left and right comers of the images show power spectra with the value stmctural parameter of microphase separation. 

Figure 9 shows the result of injecting 10 gA of the total low molecular weight fraction from GPC 1 (Column Code A2) into GPC 2 (Column Code Bl). With this column code, GPC 2 is performing as a High Performance Liquid Chromatograph (HPLC). Separation is based upon solubility (i.e. composition differences) rather than upon molecular size. Methyl methacrylate monomer was used as a reference and added to the solution injected into GPC 1. Concentrations of n-butyl methacrylate, styrene and conversion are readily calculated from the peak areas and initial concentrations. 

The adsorption of block and random copolymers of styrene and methyl methacrylate on to silica from their solutions in carbon tetrachloride/n-heptane, and the resulting dispersion stability, has been investigated. Theta-conditions for the homopolymers and analogous critical non-solvent volume fractions for random copolymers were determined by cloud-point titration. The adsorption of block copolymers varied steadily with the non-solvent content, whilst that of the random copolymers became progressively more dependent on solvent quality only as theta-conditions and phase separation were approached. 

Ruthenium(II)-NHC systems ean be used for atom transfer radical polymerization (ATRP). Generally, similar results as for the analogous phosphine complexes are obtained. For the ATRP of styrene and methyl methacrylate (MMA) [(NHC)2peBr2] was found to rival copper(I)-based systems and to yield poly (MMA) with low polydispersities. Polymerizations based on olefin metathesis that are catalyzed by ruthenium-NHC complexes are discussed separately vide supra). 

Copolymerization of a monomer having two styrene moieties attached to a chiral template molecule with a comonomer e.g., methyl methacrylate) gives copolymers with strong optical activity after removal of the template molecules. In this case styrene diads of an S,S configuration separated from other styrene diads by comonomeric units are responsible for the optical activity. 

In this paper a generalized approach is presented to the derivation of H-H-S equations for multispecies polymers created by addition polymerization across single double bonds in the monomers. The special cases of copolymers and terpolymers are derived. This development is combined with experimental results to evaluate the numerical parameters in the equations for poly(styrene-acrylonitrile ) (SAN) in three separate solvents and for poly(styrene-maleic anhydride-methyl methacrylate) (S/HA/MM) in a single solvent. The three solvents in the case of SAN are dimethyl formamide (DMF), tetrahydrofuran (THF), and methyl ethyl ketone (MEK) and the solvent for S/HA/HH is HER. 

The attractions of a drying agent which forms a homogeneous mixture with the substance to be dried, e.g. triethyl aluminium or dibutyl magnesium with hydrocarbons and some other compounds, are obvious the former can be used with methyl methacrylate, the latter with styrene and with dienes. However, it is questionable whether the difficulty of separating the dried compound completely from unused drying agent and the fire-hazard associated with many metal alkyls make the effort worth while, except in some special cases. 

This section deals with the effect of monomeric sequences in copolymer chains upon TLC separation. A possibility of separating copolymers by the difference in their chain architectures was first demonstrated by Kamiyama et al. S9 For the preliminary TLC experiment they used copolymers composed of styrene and methyl methacrylate, for the reason that this comonomer pair is endowed with the possibility of being polymerized to three different chain architectures, namely, alternating61 , statistical, and block. 

Porous silica is most widely used as adsorbent, but bonded phase materials with polar groups or crosslinked acrylonitrile39> have also been tested. Silica requires painstaking control of activity. In the separation of poly(styrene-co-methyl methacrylate) samples with dichloroethane—chloroform mixtures, clearer results were obtained with a silica column previously rinsed with methanol40. Continuously decreasing activity of silica columns was observed in the elution of poly(styrene-co-methyl acrylate) with CCU-methyl acetate mixtures38). 

Fig. 9. Copolymer separation. Gradient elution of the mixture of three poly(styrene-co-methyl methacrylate) samples on a silica column (250 x 6 mm d0 = 5nm dP = 9pm). Gradient 1,2-dichloroethane/tetrahydro-...

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