Poly film anionic polymerization

Application of amphiphilic block copolymers for nanoparticle formation has been developed by several research groups. R. Schrock et al. prepared nanoparticles in segregated block copolymers in the sohd state [39] A. Eisenberg et al. used ionomer block copolymers and prepared semiconductor particles (PdS, CdS) [40] M. Moller et al. studied gold colloidals in thin films of block copolymers [41]. M. Antonietti et al. studied noble metal nanoparticle stabilized in block copolymer micelles for the purpose of catalysis [36]. Initial studies were focused on the use of poly(styrene)-folock-poly(4-vinylpyridine) (PS-b-P4VP) copolymers prepared by anionic polymerization and its application for noble metal colloid formation and stabilization in solvents such as toluene, THF or cyclohexane (Fig. 6.4) [42]. 

Specific properties of polysilanes have been linked to the method of synthesis.35 For example, in the case of anionic polymerization of poly[l-(6-methoxy-hexyl)-l,2,3-trimethyldisilanylene] a new type of chromism was induced in the polysilane film by the difference in the surface properties of substrates and was termed a surface-mediated chromism. The polysilane exhibited thermochromism with an absorption maximum at 306 nm at 23°C, but <15°C a band at 328 nm began to appear. A monolayer of the polysilane was transferred onto both a clean hydrophilic quartz plate and a hydrophobic one treated with hexamethyldisilazane by the vertical dipping method. With the hydrophobic plate, a broad UV absorption at 306 nm is obtained, whereas the absorption on a hydrophilic plate shifts to 322 nm. The conformation of the polysilane is preserved by hydrogen bonding between the silica surface and the ether section of the substituent on the hydrophilic plate. The polysilane is attached to the hydrophobic surface only by van der Waals forces, and this weaker interaction would not sustain the thermodynamically unstable conformational state that is attained on the water surface. 

ABC copolymers polystyrene-polyisoprene-poly(vinyl-2-pyridine)(S.I.V2P) with number-molecular average weight of 23000,102000, and 23000 were prepared by stepwise anionic polymerization. Films obtained by solvent casting from methylcyclohexane and benzene were observed by electron microscopy after staining the polyisoprene block with osmium tetroxide or the poly(vinyl-2-pyridine)... 

Two copolymers, a poly(styrene-6-isoprene-7>-styrene) (SIS) triblock (60 wt% S Mn=100,000, Mw/Mn=1.04) and a poly(styrene-Wsoprene) (SI) diblock (70 wt% S Mn=50,000, Mw/Mn=1.05), were synthesized by anionic polymerization. The selective solvent used here was an aliphatic white mineral oil (MO) produced by Witco (380PO). Specific masses of each copolymer and MO weae dissolved in cyclohexane and cast into molds. Upon solvent evaporation, the resultant films were vacuum-dried for up to 7 h at 120 C. Steady-shear tests were performed on a Rheometrics dynamic stress rheometer (DSR) as a function of shear stress (x) to measure the solution viscosity (q), while dynamic tests were performed here to discern G and G" as functions of x, oo and temperature. 

Poly(DBF) prepared by the anionic polymerization of using 9-fluorenyllithium in tetrahydrofuran (THF) at -78 °C (M =1,070, A/ /A/n=1.38, SEC using oligo(DBF)s as the standard sample) (20 mg) and 2,4,7-ttinitrofluorenylidene-9-malononitrile (TNFMN) (1.0 mg) as an acceptor were dissolved in chloroform (1.0 mL), and the solution was cast on an indium tin oxide (ITO) glass plate and slowly dried under air to afford a thin film (thickness 5 pm). A circular Au electfode (thickness 20 nm, diameter 5 mm) was vacuum deposited onto the film to produce a sandwich-type cell for the drift mobility measurement (Fig. 27). 

To summarize this section, asymmetric anionic polymerization afforded poly(PDBF)s showing signihcant CD absorptions in film although their intensity of chiroptical properties is below detectable level in solution. The polymers belong to a new class of optically active vinyl polymers whose chiroptical properties originate only from a chiral conformation in the absence of any configurational information. 

Although the exact mechanism of the fluorenone formation is not known, it is believed that the monoalkylated fluorene moieties, present as impurities in poly(dialkylfluorenes), are the sites most sensitive to oxidation. The deprotonation of rather acidic C(9)—H protons by residue on Ni(0) catalyst, routinely used in polymerization or by metal (e.g., calcium) cathode in LED devices form a very reactive anion, which can easily react with oxygen to form peroxides (Scheme 2.26) [293], The latter are unstable species and can decompose to give the fluorenone moiety. It should also be noted that the interaction of low work-function metals with films of conjugated polymers in PLED is a more complex phenomenon and the mechanisms of the quenching of PF luminescence by a calcium cathode was studied by Stoessel et al. [300],... 

There are a few reports of poly(naphthalene) thin films. Yoshino and co-workers. used electrochemical polymerization to obtain poly(2,6-naphthalene) film from a solution of naphthalene and nitrobenzene with a composite electrolyte of copper(II) chloride and lithium hexafluoroarsenate. Zotti and co-workers prepared poly( 1,4-naphthalene) film by anionic coupling of naphthalene on. platinum or glassy carbon electrodes with tetrabutylammonium tetrafluoroborate as an electrolyte in anhydrous acetonitrile and 1,2-dichloroethane. Recently, Hara and Toshima prepared a purple-colored poly( 1,4-naphthalene) film by electrochemical polymerization of naphthalene using a mixed electrolyte of aluminum chloride and cuprous chloride. Although the film was contaminated with the electrolyte, the polymer had very high thermal stability (decomposition temperature of 546°C). The only catalyst-free poly(naphthalene) which utilized a unique chemistry, Bergman s cycloaromatization, was obtained by Tour and co-workers recently (vide infra). 

Vinylcarbazole polymers and their CT complexes are widely known for their excellent photoconductive properties [115]. The CT processes in this polymer system have been extensively worked out by the conventional absorption spectroscopic techniques, but the application of the XPS technique to them has been rather limited [116]. For poly(Af-vinylcarbazole) (PVK)/perchlorate complex film synthesized via electrochemical polymerization and oxidation, it was shown that the NIs core-level spectrum exhibits a new high BE component shifted by about + 3.0 eV from the neutral carbazole nitrogen at about 400 eV. This new component was attributed to the positively charged carbazole nitrogen associated with CIO4 anion [117],... 

Yimg-Chein luo et al. prepared amperometrie ammonium ion sensor based on PANi-poly(styrene sulfonate-co-maleic acid) composite eondueting polymeric electrode. Two kinds of PANi- PSSMA composite films were prepared and their ammonium ion-sensing were studied. PANi- PSSMA(I) was prepared by ineorporating PSSMA anions into a... 

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