Polystyrene preparation

The annual production of styrene in the United States is approximately 1 2 X 10 lb with about 65% of this output used to prepare polystyrene plastics and films Styrofoam coffee cups are made from polystyrene Polystyrene can also be produced m a form that IS very strong and impact resistant and is used widely m luggage television and radio cabinets and furniture... 

A curve showing the differential weight fraction versus chain length for the batch-prepared polystyrene is given in Figure 3. Figure 4 illustrates the exit age distributions obtained from the RTD experiments with benzene and with a 30 weight percent polymer solution. 

Fig.46. Dependence of [r ] on theMn of polymers prepared by anionic polymerization of 1,4-DVB in THF. The symbols represent linear ( ) branched (V) and microgel ( ) structures. The dashed line represents the [iq]/Mn relationship of anionically prepared polystyrene. [Reproduced from Ref. 231 with permission, Hiithig Wepf Publ., Zug, Switzerland].

Advincula et al. used the same initiator type (DPE activated with u-BuIi) to perform LASIP from colloidal sihca [265] or clay [266, 267]. The spacer between the DPE unit and the surface active group (quatemized amine for clay and chlorodi-methylsilane for silica) was a long n-alkyl chain. In all cases, a relatively broad polydispersity for the prepared polystyrene bmsh (PDI = 1.2-2) was observed. 

The living nature of the poly(styryl)anion allows one to prepare block copolymers with a great deal of control of the block copolymer structure. The preparation of diblock, triblock, and other types of multiblock copolymers has been reviewed [29-32]. Several of these block copolymers are in commercial use. The basic concept involves first preparing polystyrene block [RSt StLi—see Eq. (2)] and then adding a new monomer that can be added to start another growing segment. 

Tour et al. (2) prepared polystyrene having an Mn of 60,000 Da reinforced with nanotubes and observed that composites displayed an enhancement in their tensile modulus without a large reduction in their strain-at-break properties. 

Froelieh,D., Crawford,D., Rozek,T., Prins,W. Ideal network behavior of amonically prepared polystyrene gels. Macromolecules 5,100-102 (1972). 

A universal calibration curve (log [> ] Mw vs. elution vol.) was prepared for the gel permeation chromatograph using samples of anionically prepared polystyrene (Fig. 7). The figure includes samples of polyf4-methyl-1 -pentene). It has been found that polymers for which the relationship between log[ ] Mw and the G.P.C. elution volume is linear are generally Gaussian coils in solution. 

Figure 16.3 shows a representative example of the synthesis of peptides using the Boc strategy. Hydroxymethyl polystyrene can be used as the support or, if large peptides are to be prepared, polystyrene with the more acid-resistant PAM linker. Polyacrylamides [17] with a benzyl alcohol linker are also compatible with the Boc Strategy-... 

Even this rather primitive apparatus, working with a mean reproducibility of only some per cent, shows a strong dependence of the resolution on the column temperature 2), as can be seen from Fig. 2 While the measured elution curve of a 1 1-mixture of two anionically prepared polystyrenes (I Mw = 135,000 and II Mw = 415,000) shows a light shoulder at 27 °C, a practically complete resolution is achieved at 25 °C — a result which could not be obtained in GPC at that time. 

Fig. 2. Elution curves of a 1 1-mixture by weight of two samples of anionically prepared polystyrenes for three temperatures as indicated Mw = 135,000 (I) and 415,000 (II) (300 mg in 20 ml of cyclohexane 1,2))...

The tacticity of anionically prepared polystyrenes has been the subject of extensive study by a number of groups of workers, mostly by means of 13C-NMR spectroscopy. From a study of the aromatic Cl resonances, Matsuzaki and coworkers found 234) that there is a tendency towards syndiotacticity when using -butyl-Iithium in toluene as initiator. From the sensitivity of the CMR spectrum to the nature of the solvent employed it was concluded that the polymerization did not conform to Bernoullian statistics. Randall examined the methylene resonances in the CMR spectrum and concluded that butyllithium initiated polystyrene is essentially atactic 235) and that propagation is Bernouillian. Uryu et al.236) examined polystyrene... 

Following Milkovich 356), Masson, Franta and Rempp 3571 have prepared polystyrene terminated with an ester group, i.e.,... 

Styrene-Divinylbenzene Networks. Using ionic polymerization methods, Rietsch et al. (1976) prepared polystyrene (PS) networks with a well-controlled length of elastically active chains and crosslinks of variable functionality. In a given series, the glass transition temperature obeys the classical free volume theory ... 

Preparation of latex Samples. Two-stage latex samples were prepared by emulsion polymerization of the second-stage monomer mix in the presence of the first-stage polymer latex. The first-stage latexes were either in-situ or separately made using an externally prepared polystyrene latex seed. The mode of polymerization was a semi-continuous process for both stages. 

A series of latex samples with varying S/B ratios in the second stage (LS-7, LS-8 and LS-9) was prepared at 90°C, using an externally prepared polystyrene latex of 1350 A. The second-stage S/B ratios were 70/30, 90/10, and 95/5, respectively. The stage ratio was 20/80. Neither vinyl acid nor chain transfer agent was used. 

In order to facilitate solid-phase Stille coupling chemistry, Nicolaou and coworkers prepared polystyrene-di-butyltin hydride50. While this polymer has been reported previously51, the preparation on a 2% cross-linked resin represents a novel extension. 

The effects of solvents and their properties on electro-spinnability of the as-prepared polystyrene (PS) solutions and the morphological appearance of the as-spun PS fibers were investigated qualitatively by means of a scanning electron microscope (SEM) in [62]. The eighteen solvents used were benzene,t-butylacetate, carbontetrachloride, chlorobenzene, chloroform, cyclohexane, decahydronaphthalene (decalin), 1, 2-dichloroethane, dimethylformamide (DMF), 1,4-dioxane, ethylacetate, ethylbenzene, hexane,... 

Moore [1] prepared polystyrene having a Mn of 130,000 daltons with a PDI of 1.05 by initially drying the monomer and neutralizing impurities with n-butyllithium prior to polymerization. n-Butyl-lithium was also used with potassium t-amyloxide by Malanga [2] in preparing ultra-pure poly(a-methylstyrene). 

Using the RAFT chain transfer agent dibenzyltrithiocarbonate with oleic acid, tripotassium phosphate, potassium hydroxide, and potassium persulfate, Parker [3] prepared polystyrene by emulsion polymerization. The polystyrene latex was obtained in roughly 90 minutes and had a sohd content of 20.6%, while purified polystyrene had a M of 54,000 daltons with a PDI of 1.17. 

More recently, Biswas and Chatteijee have prepared polystyrene electro-philically substituted with phthalic anhydride pyromellitic diianhydride tri-mellitic anhydride and 1,2,3,4-tetrahydrophthalic anhydride by Friedel-Crafts reaction. These anhydride-modified polystyrenes have further been converted into sulfonic acid resins by conventional sulfonation reaction. The thermal stabilities of these modified polymers are comparatively better than that of unmodified polystyrene. Ion-exchange capacities also compare favourably with the polystyrene-based commercial resins. 

Titanium complexes containing polymerizable vinyl-substituted aryloxide ligands have been employed to prepare polystyrene/divinylbenzene-based polymers that incorporate Ti aryloxide fragment into the matrix 446 Such materials have been used to catalyze Diels-Alder reactions with high diastereoselectivity and at rates only three to five times slower than the corresponding homogeneous reactions. ... 

Partially chloromethylated or bromomethylated anionically prepared polystyrenes have been used for the preparation of several graft copolymers containing PS backbones and PI,43 P2VP,45 139 P4VP,140 PtBuMA,45 and PEO141142 branches. Some of these copolymers are precursors for amphiphilic graft copolymers (Scheme 64). 

Viscosity data for three linear polymers corrected to the friction coefficient of high molar mass polymer at roughly 7 g+ 120K, fit to Eq. (8.137) (curves). Open circles are polyisobutylene (r=50°C) with Mc = 14000 gmoP. filled squares are polybutadiene (7 =25°C) with A/< = 6700gmor open triangles are free radically prepared polystyrene T =217°C), and filled triangles are anionically prepared polystyrene T=2[1 C) with... 

Cahard and coworkers prepared polystyrene-bound cinchona alkaloids (PS-CA, 119), and successfully applied to enantioselective a-fluorination of silyl enol ether 117. Soluble-phase PS-CA along with Selectfluor gave both good chemical and optical yields. Facile recovery of the PS-CA by solid/liquid separation allowed an... 

It has been shown by Egner et al. (64,65) that it is possible to analyze compounds directly from prepared polystyrene beads. This approach has been useful to verify and improve the synthetic method for the generation of combinatorial libraries. Assuming that there are approximately 106 beads in 1 gram of polystyrene resin, and the substitution factor for the solid phase chemistry is 0.4 mmol/g or more, there is about 400 pmol of compound attached to each single bead. MALDI-TOF analysis has detection limits in the femtomole region, which makes it compatible with single-bead analysis (76). 

Moad et al.10 have prepared polystyrene using BPO 90% enriched at the carbonyl carbon and analysed benzoyl carbonyl carbon signals by referring to I3C NMR data for various benzoate esters. They found that at least four types of benzoyloxy groups were attached to the polymer ... 

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