I poly

Polyphenylene polymers can be prepared by this coupling. For example, the preparation of poly(/i-quaterphenylene-2,2 -dicarboxylic acid) (643) was carried out using aqueous NaHCO and a water-soluble phosphine ligand (DPMSPP)[5I I]. Branched polyphenylene was also prepared[5l2). 

Introduced in 1972, the whoUy aromatic polyamide, poly i ra-phenylene teraphthalamide), termed aramid, was the subject of extensive evaluation as a tire cord in all types of tires (8,14). As of the late 1990s, however, only specialized appHcations have emerged for aramid tire cord that draw on their high strength-to-weight ratio to produce tires with lower weight (16). 

I D. Rubin, Poly (I-Butene) Its Preparation and Properties, Gordon and Breach, New York (1968). 

M. G., Westbrook, L. S., Shannon, W. M., and Kende, M., Development of injectable, controlled-release poly(I.C) microcapsules for the inhibition of viral replication, Proc. Int. Symp. Control. Rel. Bioact. Mater.. 14. 275, 1987. 

The microencapsulation and controlled release of nucleic acids, e.g., poly(I C), for the stimulation of interferon production has been patented (87). 

Interferon is a low molecular weight protein, produced by vims-infected cells, that itself induces the formation of a second protein inhibiting the transcriphon of viral mRNA. Interferon is produced by the host cell in response to the vims particle, the viral nucleic and non-viral agents, including synthetic polynucleides such as polyinosinic acid polycytidylic acid (poly I C). There are two types of interferon. 

We report here studies on a polymer fi1m which is formed by the thermal polymerization of a monomeric complex tris(5,5 -bis[(3-acrylvl-l-propoxy)carbonyll-2,2 -bipyridine)ruthenium(11) as its tosylate salt,I (4). Polymer films formed from I (poly-I) are insoluble in all solvents tested and possess extremely good chemical and electrochemical stability. Depending on the formal oxidation state of the ruthenium sites in poly-I the material can either act as a redox conductor or as an electronic (ohmic) conductor having a specific conductivity which is semiconductorlike in magnitude. 

It was noted early in our studies of monomeric analogs of I that significant changes occurred in the visible spectrum upon conversion between oxidation states changes which translate into vivid, visual differences in color. These differences in color are also very apparent in poly-I and thus make it of interest as an e 1 ectrochromic material (61. 

Figure 3 shows the cyclic vo1tammogram of an aceton i tr i 1 e solution containing 9-fluorenone on a bare Pt electrode and on a Polv-1 coated Pt electrode using II as the electrolyte. The only significant difference between the vo1tammograms is the presence of the poly-I reduction and oxidation waves for the coated electrode. We have previously determined by other means that poly-I films should not be permeable to molecules as large as 9-... 

Figure 4. Plot of poly-I conductivity as a function of potential. A series of potential step of 20mV were employed on a sandwich electrode. Each potential was held until Faradaic current ceased, where upon a DC conductivity measurement, AE = 60MV, was taken, before proceding with the next potential. The results are for 0.05 M II electrolyte in acetonitrile vs. Ag+/Ag.

The data in Figure 5 can now be considered in light of the conduction model developed above. As stated previously, conduction in reduced poly-I behaves like an activated process. There are two sources that potentially could be responsible for this behavior. The first is the Boltzmann type concentration dependence of the 1+ and 1- states discussed above. The number of charge carriers is expected to decrease approximately exponentially with T. The second is the activation barrier to self-exchange between 1+ and 0 sites and 0 and 1- sites. For low concentration of charge carriers both processes are expected to contribute to the measured resistance. 

Another factor which appears to be of importance in the conductivity behavior of zero-valent poly-I is the absence of nonelectroactive ions in the polymer. The difference in potential between the 2+/1+ and 1+/0 couples in solution is significantly smal ler than the difference in potential between the 1+/0 and 0/1-... 

Fig. 22. Dependence of the absorption spectrum of P/3DMP-C104 (poly-/i-dimethyl pyrrole) on the reducing potentials. The voltages written in the figure are the applied voltages between the working and counter electrodes. The numbers in parentheses are the molecular ratios of the perchlorate ion to a pyrrole ring. Each spectrum is obtained using a different free standing film which has almost the same thickness as the others. Reproduced from [377].

A. Poly(/i-amino)borazines Prepared in a One-Step Process 156... 

D. Poly(/i-borylamino)borazines Prepared in a Two-Step Process 166... 

Poly[/i-(alkylamino)borazines] can be prepared through a multistep thermolysis process involving tris(monoalkylamino)boranes of the type B(NHR)3 (R = Me, Pr ). Heating these molecular precursors under reduced pressure or in an inert atmosphere... 

In our research,16171819 we first prepared a series of tris(/i-alkylamino)borazines that possess different pendent groups. This allowed us to investigate the effect of the nature of the /i-(alkylamino) substituents on both the viscoelastic behavior of the thermal properties and, therefore, the melt spinnability of the resulting poly[/i-(alkylamino)-borazines] polymers. 

The same authors proposed an alternative methods for obtaining soluble poly(/i-vinylborazine) homopolymers and poly(styrene-co-B-vinylborazine) copolymers 28 In fact, gentle polymerization conditions in solution at 80°C using Azobisisobutyronitrile (AIBN) (1.6 mol%) as an initiator provided soluble homopolymers. The polymer displays typical Mw and Mn values of —18,000 and 11,000, respectively, whereas an increase in the AIBN concentration results in a decrease in the molecular weight, contrary to what is usually observed in free-radical polymerization. 

Two-step synthetic routes to poly(/i-aminoborazines) from /i-chloroborazines involve initial nucleophilic reaction of the /i-chloroborazine with appropriate linking reagents followed by a deamination reaction of the as-obtained /i-aminoborazine. The 5-tiichloroborazine undergoes nucleophilic attack by ammonia or amine derivatives on the boron atom linked to chlorine atoms. For the same reasons previously quoted a tertiary amine (e.g., Et3N) must be added to precipitate the corresponding hydrochloride. 

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