Polystyrene functionalization

Some strategies used for the preparation of support-bound thiols are listed in Table 8.1. Oxidative thiolation of lithiated polystyrene has been used to prepare polymeric thiophenol (Entry 1, Table 8.1). Polystyrene functionalized with 2-mercaptoethyl groups has been prepared by radical addition of thioacetic acid to cross-linked vinyl-polystyrene followed by hydrolysis of the intermediate thiol ester (Entry 2, Table 8.1). A more controllable introduction of thiol groups, suitable also for the selective transformation of support-bound substrates, is based on nucleophilic substitution with thiourea or potassium thioacetate. The resulting isothiouronium salts and thiol acetates can be saponified, preferably under reductive conditions, to yield thiols (Table 8.1). Thiol acetates have been saponified on insoluble supports with mercaptoethanol [1], propylamine [2], lithium aluminum hydride [3], sodium or lithium borohydride, alcoholates, or hydrochloric acid (Table 8.1). 

Polymer-linked MWCNT nanocomposites were prepared by reversible addition fragmentation chain transfer (RAFT). The RAFT reagent was successfully grafted on to the surface of MWCNTs and PS chains were grafted from MWCNTs via RAFT polymerization [192], By covalently linking acyl chloride functions of functionalized MWCNTs with living polystyryllithium, Huang et al. succeeded in the preparation of polystyrene-functionalized MWCNTs (Scheme 1.32) [193],... 

Scheme 1.32 Covalently linking of MWCNT-acyl chlorides with living polystyryllithium for the preparation of polystyrene-functionalized MWCNTs.

As shown in Table III, supported Mo catalysts may be derived not only from the traditional Mo02(acac)2, Mo naphthenate, or Mo(CO)6 precursors. A yellow Mo peroxide complex, synthesized from Mo metal and hydrogen peroxide, was immobilized on a cross-linked polystyrene functionalized with triethylenetetramine (229). This Mo-containing material was capable of catalyzing the epoxidation of various olefins with t-BuOOH as the oxidant in the temperature range of 298-333 K. For example, cyclohexene oxide was obtained in 90% yield after 5 h of reaction at 333 K in benzene. 

Reynhout et al. [52] recently published a completely solid phase method for the synthesis of peptide-based triblock copolymers. Amine-functionalized polystyrene was first coupled to an aldehyde-modified resin to give a polystyrene functionalized secondary amine on the resin, which could then be coupled to the next amino acid (Fig. 11). Then the sequence Gly - Ala - Asn -Pro - Asn - Ala - Ala - Gly (GANPNAAG)—a known -hairpin folding peptide found in the CS protein of the Malaria parasite plasmodium falciparum— was synthesized, using standard Fmoc peptide chemistry. After removing the final Fmoc group from the peptide, a carboxylic acid-functionalized polystyrene was coupled to the terminal amine. 

FIGURE 3.2.6 Titanium oxide core-polystyrene (TiOj-PS) shell nanoparticle gate dielectrics. Bottom graph shows particle size distrihntion of as-synthesized TiOj-oleic, and polystyrene functionalized TiOj-PS particles as determined by DLS. 

Rh catalysts on polystyrene functionalized with optically active phosphines such as DIOP or DBP-DIOP have been used in asymmetric hydroformylation reactions at 2.7-9 MPa and 40-80 C. For c/s-but-2-ene equiv-... 

With the AFM tip as the cathode, nanowires of polycarbazole were also patterned by electric-field-induced cross-Unking and polymerization of carbazole units on an Au/mica or Si substrate (anode) spin-coated with insulating poly(vinylcarbazole) film [23,24]. Figure 10.9 shows a schematic of the experimental setup and Figure 10.10 shows an AFM image of the patterned CP nanostractures [24]. Similarly, electrochemical oxidation and cross-linking of carbazole and thiophene due to the flow of electrons from the conductive AFM tip to the polymer (polystyrene functionalized with carbazole and thiophene groups) precursor film on an Si substrate produced CP nanofeatures in the precursor polymer film [25]. 

Fig. 5 Films of intrinsically immiscible polymers with and without promotion by supramolecular linking, (a) Heterogeneous film of plain poly(butylmethacrylate) and polystyrene functionalized with 2,7-diamido-l,8-naphthyridine (DAN), (b) Transparent blend of poly(butylmethacrylate) functionalized with ureidoguanosine (UG) and polystyrene functionalized with DAN, thereby enabling quadruple hydrogen bonding of DAN and UG to facilitate polymer mixing. Reprinted with permission from [101]. Copyright 2006 American Chemical Society...

Many types of Clark sensor have been prepared. An example of a small flow-through sensor fabricated from a printed circuit board is shown in Fig. 9. The gelatin layer contains a depolarizer (KCl) for the reference electrode and polystyrene functions as a gas permeating membrane [126]. 

Huang, H.M. Liu, I.C. Chang, C.Y. Tsai, H.C. Hsu, C.H. Tsiang, R.C.C. (2004). Preparing a polystyrene-functionalized multiple-walled carbon nanotubes via covalently linking acyl chloride functionalities with living polystyryllithium. Journal of Polymer Science, Part A Polymer Chemistry, 42, 5802-5810. 

The electronic spectra of polystyrenes functionalized by the method of Chwastowska and Kosiarska (10) display a maximum around 268 nm and a very flat, hoad absorption between 400-700 nm. The solid di-P-naphthylthiocarbazone itself in a Nujol mull exhibits absorptions at 270, 340, and 600-750 nm but the maxima cannot be estimated precisely. In the infrared spectra of polystyrenes functionalized by the method of Chwastowska and Kosiarska (10) new bmids noticeable as shoulders around 1200,1383,1475, and 1583 cm" indicate anchored di-p-naphthylthiocarbazone. 

The di-p-naphthylthiocarbazone-supportcd polystyrenes functionalized by the method of Chwastowska and Kosiarska (10) were tested in reactions with Pb and Hg " cations in aqueous solution. In this connection several mg of modified polymer were shaken with 0.005 M aqueous solutions of Pb " and Hg cations for several minutes. The resulting suspensions exhibited pink and violet-ied reflections in contrast to the corresponding metal-free polymers. The solids were filtered off, wash( with water, and air dried. The amounts of solids were not sufficient to obtain reasonable electronic spectra in the solid state but allowed us to obtain their infrared spectra. 

The most significant differences in the infrared spectra of di-p-naphthylthio-carbazone-supportwl polystyrenes functionalized by the method of Chwastowska and Kosiarska (10) upon treatment with heavy metals were observed in the 1100-16(X) cm- region. Thus the infrared band around 1382 cm- vanished from spectra of samples treated with Pb and Hg2+. Instead a set of bands around 1310, 1341, and 1360 cm" was observed. The bands at 1152, 1474 and 1583 cm for anchored di-P-naphthylthiocarbazone were shifted to 1176 and 1173 cm-, 1491 and 1486... 

A complex with cyclometallated 2-arylpyridine is employed as the pendant groups of polystyrene functionalized by triphenylamine and isoxazoles 526." The random co-polymer containing these functional groups in the side chain shows near-white organic light-emitting properties. 

Ryu, S.W., Asada, H., and Hirao, A. (2002) Synthesis of novel well-defined substituted polystyrenes functionalized with two and four benzyl bromide moieties in each monomer unit and their application to densely branched polymer synthesis. Macromolecules, 35,7191-7199. 

Scheme 21 shows the synthesis of polystyrenes functionalized with cationic ruthenium complexes." These polymers (81) were prepared via coordination of Ru Cp, Ru CgHii, or Ru+H(PCy3)2 to the aromatic rings of polystyrene. Depending on the bulkiness of the hgand attached to rutheniiun, 25-90% of the aromatic rings in the polymers became complexed to the ruthenium. There have not yet been any reports on the polymerization of analogous styrene monomers. 

With a view to application in combinatorial chemistry and to reduce solubility problems, Muller et al. [26] developed a solid-phase approach to SPHs in 1995. Uronic acid 7 was coupled to benzhydrylamine polystyrene functionalized with... 

As moitioned b ie, composites can be prepared electrochemically, typically by polymerizing the monomer on an electrode that had been pretreat with a pol)rmer. This process has beat performed with pyrrole using (with a variety of modifications as well) poly(vinyl alcohol), pol)Kvinyl diloride), polyurethane, and as a graft onto polystyrene functionalized with benzyl chloride side- ains. Pyrrole has been mixed with Kevlar (an ultra high modulus polymer) and chemically polymerized to form a very strong "alloy" fiber of polypyrrole and Kevlar. s... 

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