Pyrrole/styrene copolymers

Figure 11.20. Chemical structure of pyrrole/styrene copolymer.

Preparation scheme for poly(pyrrole-styrene) copolymers as adopted by Nazzal and Street [138]. 

Many synthetic latices exist (7,8) (see Elastomers, synthetic). They contain butadiene and styrene copolymers (elastomeric), styrene—butadiene copolymers (resinous), butadiene and acrylonitrile copolymers, butadiene with styrene and acrylonitrile, chloroprene copolymers, methacrylate and acrylate ester copolymers, vinyl acetate copolymers, vinyl and vinyUdene chloride copolymers, ethylene copolymers, fluorinated copolymers, acrylamide copolymers, styrene—acrolein copolymers, and pyrrole and pyrrole copolymers. Many of these latices also have carboxylated versions. 

Cross-linked poly(pyrrole-g-styrene) copolymers were prepared by the electropolymerization of pyrrole in the presence of polystyrene-bound pyrrole (95). Films grown from 1 1 mixtures of pyrrole and the pyrrole-ftmc-... 

Pyrrolidinone, 1-vinyl-, polymer with styrene. See Vinylpyrrolidone/styrene copolymer Styrene/PVP copolymer Pyrrolidone. See 2-Pyrrolidone 2-Pyrrol idone... 

Vi nyl pyrrol id i none-styrene polymer Vinylpyrrolidone/styrene copolymer Definition Copolymer from vinylpyrrolidone and styrene monomers Empirical (CsHs CeHsNO) ... 

Vi nyl pyrrol idi none-styrene polymer Classification Styrene copolymer Formula (CsHs CeHgNO) ... 

Vi nyl pyrrol idone/styrene copolymer film coextrusion, blown Nylon 6/69... 

A. I. Nazzal, G. B. Street, Pyrrole styrene graft-copolymers, Chemical Communications 1985, 375. 

An approach used to improve the mechanical properties of polypyrrole was the graft copolymerization of pyrrole with pyrrole-derivatized polystyrene [152]. The base polymer was obtained by the copolymerization of styrene and 4-chloromethylstyr-ene, followed by reaction with potassium pyrrole. The copolymer was dissolved in acetonitrile together with a... 

The synthesis of pyrrole-styrene graft copolymers has been demonstrated by several groups [138]. Pyrrole monomer is chemically grafted onto a template of styrene/Cl-Me-styrene copolymer (Fig. 5-221. The pendant pyrrole groups are then polymerized electrochemically in a solution containing additional pyrrole monomer. Conductivities of 0.4 S/cm are reported for the insoluble final product. However, the utility of this unique template polymer is again not indicated by the authors except for possibly providing "versatility for systematic modification of physical properties" [138]. 

Fig. 5-22 Template/graft synthesis of pyrrole/styrene graft copolymers. After Reference [138], reproduced with permission.

Anionic polymerization of lactams was shown to proceed according to what is called the activated monomer mechanism. With bischloroformates of hydroxy-terminated poly(tetramethyleneglycol) and poly(styrene glycol) as precursors for a polymeric initiator containing N-acyl lactam ends, block copolymers with n-pyrrol-idone and e-caprolactam were obtained by bulk polymerizations in vacuum at 30 and 80 °C, respectively361. ... 

The formation of inter- and intrapolymer complexes has also been shown to affect the polymerization kinetics. For example, Ferguson and Shah (1968) investigated the influence of intrapolymer complexation on the kinetics of AA in the presence of copolymer matrices composed of either A-vinylpyrrolidone and acrylamide or A--vi nyl pyrrol idone and styrene. The polymerization rate reaches a maximum in the vicinity of AA to VP ratio equal to one for the VP/AAm matrix. This maximum in the polymerization rate is most pronounced in the presence of copolymer with the highest content of VP. When the hydrophilic acrylamide is replaced with the more hydrophobic styrene monomer in the copolymer matrix, the observed maximum in AA polymerization rate occurred at a lower than equimolar ratio of AA to VP. The hydrophilic groups of VP were interacting with the hydrophobic nucleus consisting of the styrene units in the VP/St copolymer, and were thus unable to participate in the formation of the complex unlike in the case of VP/AAm copolymer matrix. 

The content of hemin in its copolymer with styrene generally corresponds with the monomer composition (Table 4-13) [131]. The molecular weight characteristics of the copolymers also depend on the location of double bonds in the ring (benzene or pyrrol) (Table 4-14). But a reduced polymer yield and viscosity again indicate ehain termination. 

Novel conductive composite films have been developed by Kaplin and Qutubuddin [101] using a two-step process microemulsion polymerization to form a porous conductive coating on an electrode followed by electropolymerization of an electroactive monomer such as pyrrole. The porous matrix was prepared by polymerizing an SDS microemulsion containing two monomers, acrylamide and styrene [102], The electropolymerization of pyrrole was performed in an aqueous perchlorate or toluenesulfonate solution. The effects of polymerization potential on the electropolymerization, morphology, and electrochemical properties were reported [101]. The copolymer matrix improves the mechanical behavior of the polypyrrole composite film. 

Novel conductive composite films were developed using a two-step process. The porous film coated on an electrode was prepared by polymerizing a bicontinuous microemulsion containing acrylamide and styrene monomers followed by electropolymerization of pyrrole [55]. The copolymer matrix was found to improve the mechanical behavior of the pyrrole composite film. 

An interesting alternative is the chemical oxidation of heterocycles (e.g. thiophene or pyrrole) dissolved in an organic solvent (e.g. ethanol) on the surface of various materials. Conductive coatings (thickness 0.01 pm) can be produced on films of poly(phenylene sulfone), block copolymers of butadiene and styrene (Ultrason, Styrolux), poly(vinyl chloride), and other polymer films to give transparent, antistatic films with conductivities of about 0.001 S cm . Ceramics and glass can also be coated in this way. In addition, porous... 

FeCl3.6H20 in methyl alcohol does not initiate homopolymerization of styrene, but it induces pyrrole and styrene to copolymerize [138] as seen in the data presented in Table 11.4. These copolymers were prepared by adding 0.1 mole of pyrrole and the required concentration of comonomer dissolved in 50 ml of solvents to a mixture of 0.4 M oxidant and 50 ml solvent with stirring. At the end of the reaction, the products were filtered, washed with methanol dried. F2 was determined from elemental analysis of the copolymers. 

These copolymers are prepared first by reacting the pendant chloromethyl groups on a styrene/p-chloro-methylstyrene (88/12) random copolymer with potassium pyrrole in refluxing THF overnight and then electrochemically polymerizing pyrrole onto the pendant pyrrole moiety [164,165]. 

Pyrrole is a very reactive monomer and the evidence suggests that its homopolymers and copolymers are crosslinked materials the random copolymer with 95 mole% styrene units is insoluble and the PMMA graft copolymer with 1.4% pyrrole is soluble through a 0.02 pm filter. There is no confirmation in the literature of the report that doped or neutral poly(3-alkylpyrroles) are soluble. 

Inclusion of the oxidizing agent in the insulating polymer host was also achieved by complexation of Cu witii the nitrogen atom of the pyridine rings of crosslinked poly(styrene-co-2-vinylpyridine) [62]. The complexed material was exposed to a mixture of vapors of pyrrole and water, producing a blend. The pure copolymer films show horizontally oriented lamellar microdomains, and this structure is retained after... 

Another widely used approach is the in situ polymerization of an intractable polymer such as polypyrrole onto a polymer matrix with some degree of processibil-ity. Bjorklund [30] reported the formation of polypyrrole on methylcellulose and studied the kinetics of the in situ polymerization. Likewise, Gregory et al. [31] reported that conductive fabrics can be prepared by the in situ polymerization of either pyrrole or aniline onto textile substrates. The fabrics obtained by this process maintain the mechanical properties of the substrate and have reasonable surface conductivities. In situ polymerization of acetylene within swollen matrices such as polyethylene, polybutadiene, block copolymers of styrene and diene, and ethylene-propylene-diene terpolymers have also been investigated [32,33]. For example, when a stretched polyacetylene-polybutadiene composite prepared by this approach was iodine-doped, it had a conductivity of around 575 S/cm and excellent environmental stability due to the encapsulation of the ICP [34]. Likewise, composites of polypyrrole and polythiophene prepared by in situ polymerization in matrices such as poly(vinyl chloride), poly(vinyl alcohol), poly(vinylidine chloride-( o-trifluoroethylene), and brominated poly(vi-nyl carbazole) have also been reported. The conductivity of these composites can reach up to 60 S/cm when they are doped with appropriate species [10]. 

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