Poly synthetic procedure

Poly(para-phenylenevinylene)s (PPVs) represent one of the most intensively investigated classes of rr-conjugated materials. Many synthetic procedures to generate unsubstituted and substituted PPVs have been developed. They include 1,6-polymerizations of 1,4-xylylene intermediates as well as several polycondensation methods. Parallel to the polymer syntheses, several series of PPV oligomers (OPVs) have been synthesized and characterized. Such model oligomers of different molecular size allow for a study of the dependence of electronic and optical properties on the length of the conjugated Ti-system. 

Well-defined complicated macromolecular structures require complex synthetic procedures/techniques and characterization methods. Recently, several approaches leading to hyperbranched structures have been developed and will be the focus of this section. The preparation of hyperbranched poly(siloxysilane) has been reported [198] and is based on methylvinyl-bis(dimethyl siloxysilane), an A2B type monomer, and a progressive hydrosi-lylation reaction with platinum catalysts. An appropriate hydrosilylation reaction on the peripheral - SiH groups led to the introduction of polymeric chain (PIB, PEO) or functional groups (epoxy, - NH2) [199]. 

As noted above, the synthesis of dimer involved a complicated synthetic procedure and produced very low yields. Alternative routes for deposting poly-(tetrafluoro-p-xylylene) thin film were studied the precursor method and a new... 

An example for the synthesis of poly(2,6-dimethyl-l,4-phenylene oxide) - aromatic poly(ether-sulfone) - poly(2,6-dimethyl-1,4-pheny-lene oxide) ABA triblock copolymer is presented in Scheme 6. Quantitative etherification of the two polymer chain ends has been accomplished under mild reaction conditions detailed elsewhere(11). Figure 4 presents the 200 MHz Ir-NMR spectra of the co-(2,6-dimethyl-phenol) poly(2,6-dimethyl-l,4-phenylene oxide), of the 01, w-di(chloroally) aromatic polyether sulfone and of the obtained ABA triblock copolymers as convincing evidence for the quantitative reaction of the parent pol3rmers chain ends. Additional evidence for the very clean synthetic procedure comes from the gel permeation chromatograms of the two starting oligomers and of the obtained ABA triblock copolymer presented in Figure 5. 

Among the various synthetic procedures for polysilanes is the Harrod-type dehydrogenative coupling of RSiH3 in the presence of Group 4 metallocenes (Reaction 8.1) [5,6]. One of the characteristics of the product obtained by this procedure is the presence of Si—H moieties, hence the name poly(hydrosilane)s. Since the bond dissociation enthalpy of Si—H is relatively weak when silyl groups are attached at the silicon atom (see Chapter 2), poly(hydrosilane)s are expected to exhibit rich radical-based chemistry. In the following sections, we have collected and discussed the available data in this area. 

A number of conventional synthetic procedures have been used to prepare polyimides [1—4]. These are the low-temperature condensation of 3,5-diaminoanisole with acid dianhydrides, conducted in amide solvents, followed by thermal imidisation of the poly(o-carboxy)-amides (PCA) formed low temperature condensation of 3,5-diaminoanisole with acid dianhydrides, conducted in amide solvents, followed by catalytic imidisation of PCA using a 1 1 pyridine-acetic anhydride complex as a catalyst and high temperature (160-180 °C) condensation of 3,5-diaminoanisole with acid dianhydrides, conducted in m-cresol, using quinoline, isoquinoline or benzoic acid as a catalyst. 

In poly(AAm-co-BMA)/PAAc IPNs (BMA is butyl methacrylate), the synthetic procedure applied was the sequential polymerization technique shown in Fig. 10. A monomer or set of comonomers is polymerized into a polymer gel. A second monomer is introduced and subsequently polymerized and crosslinked within the initial gel (AAm-co-BMA) matrix to form the IPN. 

In 1961, Gewald and co-workers published the synthesis of poly-substituted thiophenes involving condensation of cyanoacetate and elemental sulphur with ketones or aldehydes in a three-component reaction (Scheme 5.9). Beyond their industrial use in dyes and conducting polymers, 2,5-substituted thiophenes have shown extensive potential in the pharmaceutical industry. Most published Gewald thiophene synthetic procedures require reaction times between 8 and 48 h for the condensation step. Hoener and... 

Research on dendrimers was first focused on synthetic aspects concerning this new class of macromolecules, and a broad range of dendrimers is now available, some even commercially. The emphasis of current study has shifted from merely synthetic aspects to questions of practical applications of dendrimers and the ways in which these unique compounds are superior to known systems. Consequently, much more useful synthetic procedures are required. Schliiter et al. have reported the synthesis of dendrimers with poly(p-phenylene) (PPP) derived cores using the Suzuki polycondensation [139]. 

For any synthetic procedure there are a large number of experimental variables which can be varied to define the detailed experimental conditions. It is not likely that all these variables will have a significant influence on the result but some of them will. The first problem is therefore to determine which ones. To this end, it will be necessary to run a screening experiment for sorting out the important experimental variables. This can be accomplished by fitting a low-degree poly-... 

Poly(vinyl alcohol) is typically obtained by alcoholysis of poly(vinyl esters), for example from polyfvinyl acetate) and methanol in the presence of NaOH. The process can be completed or only partially conducted. In this latter case a copolymer (alcohol/ester) is obtained. Other synthetic procedures are used, most of them also based on the hydrolysis of poly(vinyl esters). Poly(vinyl alcohol) is typically used in the atactic form, but isotactic or syndiotactic poly(vinyl alcohols) also are known. 

Polyacrylic acid (PAA)—P2VP mixed brushes were prepared by a similar synthetic procedure, by grafting of carboxyl-terminated poly(ferf-butyl acrylate) (PtBuA) and P2VP. Afterwards, PtBuA was hydrolyzed in the presence of p-toluene sulfonic acid. The same strategy was employed to graft mixed PEL brushes on polymer surfaces. In this case plasma treatment was used to functionalize surface of polymer substrates. We introduced amino groups on the surface of PA-6 and PTFE by treatment of the polymer samples with NH3 plasma. Then the carboxyl terminated homopolymers were grafted step by step from the melt to the solid substrate via amide bonds. 

PHD polymer polyols are a special class of filled polyols developed successfully by Bayer, PHD being the abbreviation of the German name polyharnstoff dispersion or polyurea dispersions [67-69]. PHD polyols contain organic urea, oligomeric or polymeric polyurea, finely dispersed in liquid polyether polyols [67-73]. The difference between PHD polyols and graft polyether polyols is the different nature of the solid polymer dispersed (it is a heterocatenary polymer - polyurea - instead of carbocatenary polymer) which is obtained by another synthetic procedure (polyaddition reaction between a diisocyanate and a diamine instead of radical polymerisation). The reaction between the diisocyanate and the diamine, takes place in situ (reaction 6.19), in liquid poly ether. The resultant polyurea being insoluble in polyether, precipitates in the form of very fine particles ... 

The synthesis of poly(phosphazene) derivatives by single or multistep reactions of poly(phosphazene) precursors continues to represent the major pathway to new members of this class of materials. The reaction of an oxyanion with (NPClj) is the most common synthetic procedure in this area. Protected glyceral poly(phosphazenes) analogous to the cyclic homologs, 28, have been prepared and may be crosslinked by exposure to yi radiation. Acidic deprotection yields the free glyceral substituted polymers which undergo slow hydrolysis. The deprotected polymers can be crosslinked using... 

More recently, a modification of the Mayr procedure in which the weakly coordinated trifluoroacetato ligand is directly replaced by the poly(pyrazolyl)borate anion (with concomitant CO ligand displacement) has allowed development of a one-pot synthetic procedure. An early example of this involved stepwise preparation of the (alkynylmethylidyne)tungsten complexes Tp W( = CC = CR) (CO)2 (Tp = Tp, Tp R = SiMe3, Ph) from W(CO)6, Li[C = CR], (CF3C0)20 and M[Tp ] (M = Na, K) directly, as shown in Scheme 9. The complex TpMo( = CC4H3S-2)(CO)2 was similarly obtained directly from Mo(CO)6, 2-thienyllithium, (CF3C0)20 and K[Tp]. ... 

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