Poly polymers synthetic approach

In a precursor-polymer synthetic approach [288], amphiphiles which formed charged complexes with precursor polymers of poly(p-phenylene vinylene) (P(PV)) and poly(thienylene vinylene) (P(TV)) were spread onto solutions of these precursor polymers. This unique complex is then transferred to an appropriate substrate using standard LB techniques, and then converted to P(PV) or P(TV) via heat treatment. In a similar but rather novel, in-situ polymerization approach from the Rubner group [289], LB films of ferric stearate are exposed sequentially to HCl vapor (generating FeCls oxidant) and pyrrole monomer, yielding conductive LB P(Py) films. 

Poly(p-pheny lene)s, PPPs, constitute the prototype of rigid-rod polymers and are currently being intensively investigated [1]. The key role of PPPs follows from their conceptually simple and appealing molecular structure, from their chemical stability, and from their superior physical properties [2], In turn, this is the result of important advances made in aromatic chemistry over the last few years. The following section gives an overview of the most common methods to generate poly(p-phenylene)s via different synthetic approaches. 

Polyfarylene vinylene)s form an important class of conducting polymers. Two representative examples of this class of materials will be discussed in some detail here. There are poly(l,4-phenylene vinylcne) (PPV) 1, poly(l,4-thienylene viny-lenc) (PTV) 2 and their derivatives. The polymers are conceptually similar PTV may be considered as a heterocyclic analog of PPV, but has a considerably lowci band gap and exhibits higher conductivities in both its doped and undoped stales. The semiconducting properties of PPV have been shown to be useful in the manufacture of electroluminescent devices, whereas the potential utility of PTV has yet to be fully exploited. This account will provide a review of synthetic approaches to arylene vinylene derivatives and will give details an how the structure of the materials relate to their performance in real devices. 

There have been a number of different synthetic approaches to substituted PTV derivatives proposed in the last decade. Almost all focus on the aromatic ring as the site for substitution. Some effort has been made to apply the traditional base-catalyzed dehydrohalogenation route to PTV and its substituted analogs. The methodology, however, is not as successful for PTV as it is for PPV and its derivatives because of the great tendency for the poly(u-chloro thiophene) precursor spontaneously to eliminate at room temperature. Swager and co-workers attempted this route to synthesize a PTV derivative substituted with a crown ether with potential applications as a sensory material (Scheme 1-26) [123]. The synthesis employs a Fager condensation [124] in its initial step to yield diol 78. Treatment with a ditosylate yields a crown ether-functionalized thiophene diester 79. This may be elaborated to dichloride 81, but pure material could not be isolated and the dichloride monomer had to be polymerized in situ. The polymer isolated... 

An unusual synthetic approach to PF copolymers was demonstrated by Bunz and coworkers [370], who prepared poly(fluorene ethynylene) 281a-e by metathesis polymerization reaction (Scheme 2.44) [370], The aggregation of polymers 281 in concentrated solutions and in solid state is manifested in slight (up to 10-20 nm) red shift of the absorbance and emission peaks, although solutions and films emit pure blue light. 

Polycondensation of Bisphenols, II, with Phosgene. Polycondensation of siloxane-linked bisphenols, II, with phosgene is the most obvious synthetic approach leading to siloxane-modified poly(arylene carbonates) since the phosgene-bisphenol polycondensation is used in the synthesis of aromatic polycarbonates (1). This method was used initially to prepare polymer (as indicated in reaction 1) as well as for the attempted synthesis of polymers 2 and 5 ... 

Some polymers consisting entirely of head-to-head placements have been deliberately synthesized to determine if significant property differences exist compared to the head-to-tail polymers. The synthetic approach involves an appropriate choice of monomer for the particular H-H polymer. For example, H-H poly(vinyl chloride) is obtained by chlorination of 1,4-poly-l,3-butadiene,... 

Since 1985, a major effort has been devoted to incorporating heterocyclic units within the backbone of poly(arylene etherjs (PAE). Heterocyclic units within PAE generally improve certain properties such as strength, modulus and the glass transition temperature. Nucleophilic and electrophilic aromatic substitution have been successfully used to prepare a variety of PAE containing heteorcyclic units. Many different heterocyclic families have been incorporated within PAE The synthetic approaches and the chemistry, mechanical and physical properties of PAE containing different families of heterocyclic units are discussed. Emphasis is placed on the effect variations in chemical structure (composition) have upon polymer properties. 

Both polymer yields and processing can be improved by modifying the synthetic approach. Hydroboration of vinyl-substituted poly- or oligosilazanes [(H2C=CH)Si(R)-NH] , (R = H, (NH)o.s, CH3, Scheme 1) using BH3 SMe2 delivers the corresponding boron-modified polysilazanes [B(C2H4Si(R)-NH)3] , li -3i in 100% yield [5],... 

Ishizu et al.194 synthesized hyperbranched macromolecules that resemble dendrimers. The synthetic approach involved the preparation of poly(4-methyl-styrene-b-PS-b-poly(4-methylstyrene) triblock copolymer by using naphthalene lithium as difunctional initiator. The 4-methyl groups of the terminal blocks were metalated with s-BuLi/tetramethylethylenedi-amine (TMEDA) complex in a molar ratio of 1 2. After removal of the excess s-BuLi by repeated precipitation of the living polymer and transfer of supernatant solution to another flask under high vacuum conditions, the polymer was dissolved in THF and was used as the initiator of a-methylstyrene at —78 °C. After the polymerization of a-methylstyrene, a small amount of 4-methylstyrene was added. The procedure of metalation of the a-methyl groups and polymerization of a-methylstyrene can be repeated many times to form a dendritic type hyperbranched polymer (Scheme 99). The characterization of the inter-... 

This survey has demonstrated that the field of conjugated arylene vinylene polymers has matured considerably over the past thierty years. Several synthetic approaches to poly(arylene vinylenejs have been developed, and many routes now allow solution casting of polymeric materials, thereby facilitating incorpora-... 

The present state of the synthesis of poly(naphthalenecarboximides) and poly(perylenecarboximides) containing six-memhered imide rings in the hackhones is reviewed. Recent advances in synthetic approaches provide access to polymers exhibiting high thermal stability and chemical resistance, optical conductivity, and electrographic properties. The resulting polymers are high molecular-mass, soluble products that are easily processed by traditional methods. 

Synthetic Approaches to Poly(para-Phenylene)-Type Polymers... 

The synthesis and the study of intrinsic properties of well-defined cyclic synthetic polymers are still a challenge in polymer science. Approaches for their preparation were first concentrated on polymers exhibiting linear ring-chain equilibria. This corresponds to polymers containing functional groups in their backbone chain such as poly(dimethylsilox-anes) (PDMSs), polyethers, polyesters, and so forth. The synthesis of cyclic polymers from carbon-carbon chains free... 

The Michael addition is a very efficient reaction that has been widely applied for dendrimer synthesis due to a small amount of side reactions and mild reaction conditions, poly (amido amine) (PAMAM) or poly(propylene imine) (PPI) dendrimers are two well-known examples that rely on the Michael addition. Long et al. reviewed the synthetic approaches to linear, cross-linked, and branched polymers via step-growth Michael polyaddition.Thermally stable, high-Tg poly... 

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