Poly model trimer

It should be noted that most of the substitution-based synthesis work with poly(organophosphazenes) has been preceded by exploratory studies at the small molecule, model compound level, often with the use of cyclic trimer I as a model for polymer II (6). 

Possible trimer structure formed from cyclic poly(2-vmylpyridine) [P2VP] and model linear P2VP (L-l-L-3), from Ref. 29. 

Oligomeric model compounds were synthesized in order to predict properties of the poly (9,10-anthrylene vinylene), some without any alkyl substitution (dimmer [13], trimer [14]) and others with alkyl substituents (dimer with methyl in 1,4-position, trimer to heptamer with partly substitution of pentyl in 2,3-position [12]). Investigations on those model compounds made clear that exceptional charge-storage properties and... 

Trimers with poly methylene spacers 1.1 Models and methods... 

Thus, it was not until 1990 that the group of Kaminsky and Arndt-Rosenau took a more detailed look at the homopolymerization of norbornene and the structures of the resulting polymers. Driven by the growing interest in copolymers with high norbornene contents and high glass transition (Tg) temperatures, as well as the unusual properties of PNBs, Arndt-Rosenau et al. used the hydrooligomerization technique to produce saturated model norbornene dimers and trimers with metallocene catalysts known to produce atactic, isotactic, and syndiotactic poly(a-olefins) (1-3, Table 16.1). 

Besides PET and PTT, the enzyme also degrades other polymers such as PCL and poly(bisphenol-A carbonate) [30]. The lipase hydrolyzed BHPT to MHPT, but TPA could not be detected as a degradation product, indicating that the lipase was unable to hydrolyze MHPT. Cyclic PTT dimers and films were also not hydrolyzed [26]. The lipase did not release TPA from the model compound BHET, but the PET trimer was hydrolyzed to TPA, BHET, MHET, 2-hydroxyethyl-benzoate, and benzoic acid. In contrast to cutinases, 2-hydroxyethyl-benzoate was not further hydrolyzed to benzoic acid [27]. 

Arndt et al. [58, 59] gathered information about norbomene insertion and dimer and trimer microstmcture by hydrooligomerization with metallocene catalysts known to produce atactic, isotactic, and s3ndiotactic poly(a-olefins) isolation and characterization of model dimers and trimers. Norbomene was shown to undergo cis-exo insertion into the metal-carlxMi bonds, and the different stereochemistry of oligomers (and polymers) was demonstrated [58, 59]. 

Several attempts have been made to overcome the problems with metastable TPD and TAPC glasses. Recently we described the synthesis of 3,6-bis[(9-hexyl-3-carbazolyl)ethy-nyl]-9-hexylcarbazole 27, a trimeric model compound of poly(carbazolylene ethynylene) [15], This material shows a glass transition temperature of 41 °C and forms glasses which are stable for more than a year. Mobilities up to 10 cm A s ( = 6 10 V/cm, T = 30 °C) have been measured by the time-of-flight technique. 

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