Porphyrins, preparation copolymer

Although the supramolecules of SWNTs wrapped with porphyrin-containing polymers mentioned above were prepared by mixing SWNTs and the polymer in solution, a very stable complex of porphyrin-pyrene copolymer 49/SWNT was also synthesized by copolymerization of porphyrin and pyrene in the presence of soluble SWNTs as shown in Scheme 4 [132]. 

Pyridine in place of methylaluminum bis(2,6-di-tert-butyl-4-methylphenolate) (3e) was also effective for the polymerization of MAN from the living PMMA (2). An example is shown by the polymerization of MAN under irradiation with the 2 (Mn=4000,Mw/Mn=1.09 prepared with [MMA]o/[l]o=40,100% conversion)-pyridine system at the initial mole ratio [MAN]q/[2] q/[pyridine]q of 100/1.0/0.6. MAN was polymerized up to 63% conversion in 65 h [Fig. 25 ( )], where the GPC peak of the polymer formed was observed to shift clearly towards the higher molecular-weight region (Mn=7600), retaining the narrow MWD (Mw/Mn=1.26), and the peak corresponding to the prepolymer of MMA was not observed. These facts clearly demonstrate the successful polymerization of MAN from 2, affording a PMMA-PMAN block copolymer. In sharp contrast to the polymerization of MAN, polymerization of MMA with aluminum porphyrin 2 was retarded by pyridine. For example, in the presence of 2 equiv of pyridine with respect to 2, the polymerization of 100 equiv of MMA proceeded very slowly to attain 25% conversion in 18 h under irradiation, while in the absence of pyridine, the polymerization of MMA with 2 was complete within 12 h under otherwise identical conditions. 

Depending on the type of charges, polycationic PEG-P(Lys) and polyanionic PEG-P(Asp) are used for the preparation of such PIC micelles (Fig. 6). Based on recent research, core-shell type PIC micelles with a 52 nm diameter were prepared from a Zn-porphyrin-dendrimer with 32 carboxylate groups on the periphery, 32(-)DPZn, and PEG-P(Lys) block copolymers (56,57). On the contrary, when the dendrimer structure is cationic, a third-generation porph3rrin-dendrimer with 32 primary amine groups on the periphery, 32(+)DPZn, and PEG-P(Asp) were used to prepare a PIC micelle, and had a spherical structure with a 55 nm-sized diameter (58). Both... 

Porphyrins. Rollmann (21) has described the preparation of a variety of metalloporphyrins on a macroretlcular polystyrene copolymer with either divinylbenzene or ethylene glycol dimethacrylate. Polymer attachment could be made through an amine ester or ketone linkage. Cobalt(III) derivatives catalyze the oxidation of thiols in air. The polymers did show a marked tendency to age with resultant loss of activity. 

Co(II) and Fe(II) Schiff bases and porphyrin complexes have been included by casting in various copolymers containing vinylpyridine or iV-vinylimidazole units. Details on the preparation of thin films and their use in 02-transporting membranes are given in Chapter 9. The use of Pt and Pd porphyrins in polymer films as optical sensors is described in Section 10.1. 

Aluminum porphyrins have been used to prepare block copolymers by sequential monomer addition of two oxiranes [68, 318], of two )8-lactones [319], of a j5-lactone and an oxirane [319], of ethylene oxide and e-caprolactone [74] of propylene oxide and D-lactide [75], and of two methacrylates [76]. In the one example involving monomer pairs (j3-lactone and oxirane) which generate two different types of propagating species, the )8-lactone had to be polymerized... 

Moreover, the reactivation of a cobalt-terminated polymer in the presence of second monomer leads to block copolymerization. In this respect, CMRP has aheady contributed to the preparation of the valuable copolymers listed in Table 4.1. For example, well-defined poly(acrylate) block copolymers were prepared via a sequential polymerization of acrylic monomers with cobalt porphyrin la or cobaloximes 2 [14, 20]. The synthesis of well-defined poly (acrylate)-b-poly(VAc) block copolymers was also achieved with complex la [26]. Co(acac)2 (3a see Figure 4.1) is the most prolific complex for the preparation of block copolymers, until now. Indeed, the sequential CMRP of VAc with NVP [33], AN [48], or vinyl pivalate (VPi) [49] leads to the corresponding block copolymers, in controlled fashion. Throughout the polymerization, the experimental conditions were necessarily adjusted, taking into consideration the reactivity of the second monomer. As an illustration of this, well-defined PVAc-b-poly(acrylonitrile) (PAN) copolymers could only be prepared via a bulk polymerization of VAc at 30 °C, followed by the AN polymerization at 0°C in solution in DMF [48]. In this case, the DMF not only serves as the solvent but also binds the metal and adjusts its reactivity. As a rule, the PVAc sequences of these copolymers were hydrolyzed in order to provide poly(vinyl alcohol) (PVA)-containing derivatives, such as hydrosoluble PVA-b-poly... 

Finally, Ruhlmann and coworkers used also /new-dipyridyldiphenylporphyrins (porphyrins with two pyridyl substituents) in the presence of ZnOEP and obtained copolymers having two different kinds of perfectly alternating macrocycles (Fig. 17a) [139]. This method of electropolymerization appears to be the simplest one for preparation of bis-porphyrin copolymers. In order to modulate the steric hindrance of the copolymers, porphyrins bearing three or four pendant pyridyl groups were also used (Fig. 17b). 

Phthalocyanine complexes of copper and zinc have also been incorporated into copolymers of polyethers and polystyrene. Polymer 38 is an example of a polystyrene prepared by free-radical polymerization of a zinc porphyrin complex and styrene. This high molecular weight metallopolymer formed aggregates in solution. 

A ternary block copolymer, which contains amino groups in the center block, was synthesized by coupling cnt/o-telechelic poly[styrene-co-p-(ami-nomethyl)styrene] with an excess of poly(ethyleneoxide). The center block was prepared by the UV-irradiation polymerization of styrene, p-(amino-methyl)styrene, and bis(/7-acetoxyphenyl)sulfide (molecular weight 42,000). The carboxylic acid derivative of iron-porphyrin was activated with ethyl chloroformate and then reacted with the amino group of the center block of the ternary copolymer. 

Multifunctional initiators based on, for example, cyclotriphosphazine [106], silesquioxane [107], porphyrin [108] and bipyridine metal complex [109, 110] cores were also successfully used for the living cationic ring-opening (co)polymerization of 2-oxazolines, resulting in star-shaped (co)polymers. The use of polymeric initiators also allowed the construction of well-defined complex macro molecular architectures, such as triblock copolymers with a non-poly(2-oxazo-line) middle block that is used to initiate the 2-oxazoHne polymerization after functionalization with tosylate end-groups [111-113]. In addition, poly(2-oxazoline) graft copolymers can be prepared by the inihation of the CROP from, for example, poly(chloromethylstyrene) [114, 115] or tosylated cellulose [116]. 

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