Poly derivatization

Lenk T J, Hallmark V M, Rabolt J F, Haussling L and Ringsdorf H 1993 Formation and characterization of self-assembled films of sulphur-derivatized poly(methyl methacrylates) on gold Macromolecules 26 1230-7... 

In addition to providing fully alkyl/aryl-substituted polyphosphasenes, the versatility of the process in Figure 2 has allowed the preparation of various functionalized polymers and copolymers. Thus the monomer (10) can be derivatized via deprotonation—substitution, when a P-methyl (or P—CH2—) group is present, to provide new phosphoranimines some of which, in turn, serve as precursors to new polymers (64). In the same vein, polymers containing a P—CH group, for example, poly(methylphenylphosphazene), can also be derivatized by deprotonation—substitution reactions without chain scission. This has produced a number of functionalized polymers (64,71—73), including water-soluble carboxylate salts (11), as well as graft copolymers with styrene (74) and with dimethylsiloxane (12) (75). 

These products are characterized in terms of moles of substitution (MS) rather than DS. MS is used because the reaction of an ethylene oxide or propylene oxide molecule with ceUulose leads to the formation of a new hydroxyl group with which another alkylene oxide molecule can react to form an oligomeric side chain. Therefore, theoreticaUy, there is no limit to the moles of substituent that can be added to each D-glucopyranosyl unit. MS denotes the average number of moles of alkylene oxide that has reacted per D-glucopyranosyl unit. Because starch is usuaUy derivatized to a considerably lesser degree than is ceUulose, formation of substituent poly(alkylene oxide) chains does not usuaUy occur when starch is hydroxyalkylated and DS = MS. 

Diesters. Many of the diester derivatives are commercially important. The diesters are important plasticizers, polymer intermediates, and synthetic lubricants. The diesters of azelaic and sebacic acids are useflil as monomeric plasticizing agents these perform weU at low temperatures and are less water-soluble and less volatile than are diesters of adipic acid. Azelate diesters, eg, di- -hexyl, di(2-ethylhexyl), and dibutyl, are useflil plasticizing agents for poly(vinyl chloride), synthetic mbbers, nitroceUulose, and other derivatized ceUuloses (104). The di-hexyl azelates and dibutyl sebacate are sanctioned by the U.S. Food and Dmg Administration for use in poly(vinyl chloride) films and in other plastics with direct contact to food. The di(2-ethylhexyl) and dibenzyl sebacates are also valuable plasticizers. Monomeric plasticizers have also been prepared from other diacids, notably dodecanedioic, brassyflc, and 8-eth5lhexadecanedioic (88), but these have not enjoyed the commercialization of the sebacic and azelaic diesters. 

The GBR resin works well for nonionic and certain ionic polymers such as various native and derivatized starches, including sodium carboxymethylcel-lulose, methylcellulose, dextrans, carrageenans, hydroxypropyl methylcellu-lose, cellulose sulfate, and pullulans. GBR columns can be used in virtually any solvent or mixture of solvents from hexane to 1 M NaOH as long as they are miscible. Using sulfonated PDVB gels, mixtures of methanol and 0.1 M Na acetate will run many polar ionic-type polymers such as poly-2-acrylamido-2-methyl-l-propanesulfonic acid, polystyrene sulfonic acids, and poly aniline/ polystyrene sulfonic acid. Sulfonated columns can also be used with water glacial acetic acid mixtures, typically 90/10 (v/v). Polyacrylic acids run well on sulfonated gels in 0.2 M NaAc, pH 7.75. 

Free amino acids can be derivatized with isothiocyanates to phenyl- or methyl-thiohydantoin derivatives. The thiohydantoins can be separated on a CSP with poly-[Af-acryloyl-L-phenylalanine ethylester] (Chiraspher ) as a chiral selector [25]. This CSP offers a known selectivity for many five-membered heterocyclic rings. 

Starch is usually derivatized by the introduction of acrylic groups, prior to polymerization and manufacture into microspheres. Poly(acryl) starch microspheres, as they are referred to, are an example of a semisynthetic polymer system. Their extensive use as... 

Scheme 19 Synthesis and derivatization of aUcene-terminated poly(glutamates)...

Other compounds identified in caramels are di-D-fructose and poly(glycosyl) dianhydrides (DFAs). DFAs were found in caramels prepared from D-fructose, D-glucose, and sucrose. The analysis was done after derivatization as TMS (per-0-trimethylsilyl) derivatives or as TMS-oxime (per-O-trimethylsilyl oxime) by... 

Upon applying the calibration constants obtained from the data of one sample to evaluate the SEC data of the other samples, the calculated Mn and values correspond fairly well (within 10-20%) with the absolute MW parameters of the samples. This agreement also suggests that the samples probably have similar chain structures. The distribution functions for samples PN-1 and IL-22 are plotted in Figures 4 and 5. The molecular weight distributions of both polymers are similar to distribution curves reported for derivatized poly(organo)phosphazenes (4-10). 

The identification and quantification of potentially cytotoxic carbonyl compounds (e.g. aldehydes such as pentanal, hexanal, traw-2-octenal and 4-hydroxy-/mAW-2-nonenal, and ketones such as propan- and hexan-2-ones) also serves as a useful marker of the oxidative deterioration of PUFAs in isolated biological samples and chemical model systems. One method developed utilizes HPLC coupled with spectrophotometric detection and involves precolumn derivatization of peroxidized PUFA-derived aldehydes and alternative carbonyl compounds with 2,4-DNPH followed by separation of the resulting chromophoric 2,4-dinitrophenylhydrazones on a reversed-phase column and spectrophotometric detection at a wavelength of378 nm. This method has a relatively high level of sensitivity, and has been successfully applied to the analysis of such products in rat hepatocytes and rat liver microsomal suspensions stimulated with carbon tetrachloride or ADP-iron complexes (Poli etui., 1985). 

Derivatization reactions. In addition to changing the substituents in the primary precursor phosphines, (MegSi)2NPRR , two other approaches have been used to prepare polymers with more complex substituents attached to the backbone by direct P-C linkages. These are (a) alteration of R and R in the immediate N-silylphosphoranimine precursors, MegSiN=P(OOUCFo)RR , and (b) alteration of R and R in the preformed poly(alkyl/aryl-phosphazenes), (RR P=N]n. Some examples of the former method are described below and in other papers (21-23), while the use of the latter approach to prepare several silylated poly(alkyl/arylphosphazenes) has been recently reported. (20)... 

The following protocols make use of the compounds adipic acid dihydrazide and carbohy-drazide to derivatize molecules containing aldehydes, carboxylates, and alkylphosphates. The protocols are applicable for the modification of proteins, including enzymes, soluble polymers such as dextrans and poly-amino acids, and insoluble polymers used as micro-carriers or chromatographic supports. 

A method for microwave-assisted transesterifications has been described by Van-den Eynde and Rutot [73], The authors investigated the microwave-mediated deriva-tization of poly(styrene-co-allyl alcohol) as a key step in the polymer-assisted synthesis of heterocycles. Several /i-ketoesters were employed in this procedure and multigram quantities of products were obtained when neat mixtures of the reagents in open vessels were subjected to microwave irradiation utilizing a domestic micro-wave oven (Scheme 7.65). The successful derivatization of the polymer was confirmed by IR, 1H NMR, and 13C NMR spectroscopic analyses. The soluble supports... 

It should be noted that the Hantzsch-1,4-DHP synthesis can be conducted with a soluble polymer. Successful derivatization of poly(styrene-co-allyl alcohol) under the action of microwave irradiation with a variety of ethyl oxopropanoates and ethyl 3-aminobut-2-enoates were reported by Vanden Eynde s group [27]. 

Scheme 12.18 Derivatization of poly(styrene-co-allyl alcohol) with R = Me, Ph, OEt /7-dicarbonyl compounds.

Thickness Measurement. The thickness of poly(I) at different coverages was obtained using a Tencor alpha-step 100 surface profile measuring system. Electrodes used were glass slides coated with Pt by electron beam evaporation. In order to produce a "step" across which the stylus of the surface profiler was drawn, Apiezon N grease was applied to part of the electrode surface and was removed with CH2CI2 after derivatization with poly(I). 

Uster P, et al. Insertion of poly(ethylene glycol) derivatized phospholipid into pre-formed liposomes results in prolonged in vivo circulation time. FEBS Lett 1996 386 243. 

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