Poly precursor

A different methodology using the reactivity of the Si-H bond in 38 was reported in two communications, as COMC (1995) was being completed. Precursor poly[phenyl(H)silylene] 38 is conveniently prepared by the... 

The resorcinol-formaldehyde polymers have been used to prepare highly porous carbon materials, by controlled pyrolysis in an inert atmosphere [144,154], The microstructure of the carbon is an exact copy of the porous polymer precursor. Poly(methacrylonitrile) (PM AN) PolyHIPE polymers have also been used for this purpose. These monolithic, highly porous carbons are potentially useful in electrochemical applications, particularly re-chargeable batteries and super-capacitors. The RF materials, with their very high surface areas, are particularly attractive for the latter systems. 

Poly(arylene ether phthalazine)s were prepared by two different routes [47], As shown in Eq. (13), one route involved the preparation of precursor poly(arylene ether diketone)s and subsequent reaction with hydrazine while the other route concerned the reaction of difluorophthalazine monomers with various bisphen-ols. The poly(arylene ether phthalazine)s prepared by the two routes exhibited very similar Tgs. The synthetic route to the difluorophthalazine monomers is also shown in Eq. (13). A comparison of the properties of a representative series of poly (ary lene ether diketone)s and the corresponding poly(arylene ether... 

Phenanthrene is a biphenyl with an ethene bridge. Poly(2,7-phenanthryl-ene)s 81 have been prepared by polymer-analogous McMurry coupling of precursor poly(2-acyl-p-phenylene)s 82 (Scheme 36) [111]. 

In addition to the usual ligands described above, selective ligands for a series of metal ions can be introduced. An example is the ligand 8-hydroxyquinolin (oxine). Figure 12 shows the retention profiles of the complexation of poly(ethylenimin)-oxine with Fe(III) ions at different pH, when compared to the properties of the precursor poly(ethylenimin). 

Aromatic polyimides have achieved considerable success as high temperature-resistant polymers. Since the desired high molecular weight polyimides are not readily processable, they are generated in situ by the thermal ring closure of the processable precursor poly(amic-acids) ( 2). The use of low molecular weight prepolymers, i.e. poly(amic-acids), as laminating resins is limited by their conversion to an intractable state before complete elimination of volatile by-products. 

Essentially complete reductive dechlorination of the precursor poly(chlorofluoroethylene)s to PVF was achieved after 24 h at 60"C in tetrahydrofuran with a molar excess of tri(n-butyl)tin hydride and 1 mol% of azo6i s(isobutyronitrile) (11). The reaction mixture was homogeneous until dechlorination was almost complete, after which the mixture turned cloudy owing to the insolubility of PVF. 

Poly(phosphazenes) are inorganic polymers with a [ P - N ]n repeating unit in the backbone [179-183]. The precursor poly(dichlorophosphazene)... 

Just one example of an asparate-type polyamide derived from a carbohydrate precursor poly[isobutyl(25,3R)-3-benzyloxyaspartatc] (133), has... 

In order to synthesize homopolymers by polymer analogous reactions, the reaction must go to 100% conversion. Hydrosila-tions of mesogenic olefins are the most common polymer analogous reactions used to prepare SCLCPs [199]. However, the precursor poly(methyl siloxane)s are generally not prepared by living polymerizations, nor do the hydrosilations readily go to comple-... 

Combination of anionic polymerization and post polymerization reactions has been used for the synthesis of poly(acrylic acid-b-N,N-diethylacrylamide) (PAA-PDEA) copolymers [9]. Initially the synthesis of a precursor poly(tert-butylacrylate-b- N,N-diethylacrylamide) (PtBMA-PDEAAm) block copolymer was realized via sequential anionic polymerization of the tert-butyl acrylate and diethylacrylamide monomers. However, an amount of PtBMA homopolymer was detected in the crude reaction product. In order to remove the vast majority of the homopolymer, the authors proposed the precipitation of the crude product in hexane, where the homopolymer is highly soluble, in contrast to the block copolymer. The piuified block copolymer was subjected to deprotection of the tert-butyl group in acidic media, leading to the desirable DHBC. The final block copolymer showed pH and thermosensitive solution aggregation. 

DHBCs of the type poly(p-hydroxystyrene-b-methaciylic acid) (PHOS-PMAA) were also synthesized via anionic polymerization followed by acidic hydrolysis [10]. Both blocks of the precursor poly(p-tert-butoxystyrene-b-tert-butylmethacrylate) (PtBOS-PtBMA) copolymers, formed by sequential addition of the protected monomers, could be deprotected in a single step giving the desired pH-responsive block copolymers. Figure 2. Hydrolysis was found to be nearly quantitative and resulted in a series of copolymers with well defined molecular characteristics and of variable composition. 

Wu et al., reported syntheses of a series of novel azo polyelectrolytes, starting with a reactive precursor, poly(acryloyl chloride). The precursor polymer was functionalized by the Schotten-Baumann reaction with several aromatic azo compounds containing hydroxyl end groups. The degrees of functionalization were controlled by selecting suitable feed ratios between the azo reactants and poly(acryloyl chloride) The unreacted acyl chloride groups were hydrolyzed to obtain ionizable carboxylic acid structures. 

I. U. Rau, M. Rehahn, Towards rigid-rod polyelectrolytes via well defined precursor poly(pani-phenylene)s substituted by 6-iodohexyl side chains, Acta Polymerica 1994, 45, 3. 

The third method is a two-stage solution polymerization (Figure 5.26) that involves a low-temperature polycondensation of bis(o-aminophenol)s with aromatic tetracarhoxylic acid anhydrides to give high-molecular-weight soluble precursors poly(o-hydroxy amic acid)s (PHAAs), followed by a thermal conversion to form organic-insoluble PBOs [55,56],... 

Han et al. investigated the gas separation behavior of the PBOs (Figure 5.57) prepared from thermal rearrangement of the fluorinated o-HPAs [80]. The thermal rearrangement occurred at a comparatively low temperature (350 °C) than the precursor poly-imides. The cavity sizes and distribution of FFV elements were tuned to obtain a higher combination of permeability (Phj = 206 Barrer) and selectivity by changing the precursor HPA structure and thermal treatment. The reduction of CO2 solubility for PBO in comparison to the precursor HPAs improved the H2/CO2 selectivity (a = 6.2 at 210 °C, in which Ph2 > 200 Barrer) and moved the membrane performance to polymeric upper bound (Robeson upper bound). 

Fig. 34. Preparation of poly(acrylic acid) salts via hydrolysis of a precursors poly(alkyl acrylate).

Here so-called Type I and Type II zwitterionic SCK micelles can be prepared from the hydrophilic-hydrophobic precursors poly(2-(dimethylamino)ethyl methacrylate-6Zoc -2-tetrahydropyranyl methacrylate) (DMAEMA-THPMA) copolymers prepared via group transfer polymerization (128,129,461). Micel-lization of the DMAEMA-THPMA block copolymers in a water/THF mixture... 

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