Poly chain-length dependence

A convenient way to get information about the dynamics of polymers is to measure Ti, Tip and T2 by H pulse NMR. Figure 7.15 shows the side chain length-dependence of the H T2 value measured at 80°C for the side chain of poly(y-n-alkyl L-glutamate)s [26]. As seen from this figure, T2 is almost constant for n = 5-9 and suddenly becomes double for n = 10. It is easy to find the discontinuity between n = 9 and n = 10. Based on BPP theory, T2 increases as the correlation time for the motion decreases. A sudden increment of T2 means that there is a large difference in the side chain mobility between n 9 and n 10. These polymers become a thermotropic liquid crystal if the number of carbon atoms in the alkyl side chain is more than... 

Babel, A. and Jenekhe, S.A., Alkyl chain length dependence of the field-effect carrier mobility in regioregular poly(3-alkylthiophene)s, Synth. Met. 148, 169-173, 2005. 

Bondarev SL, Bachilo SM, Dvornikov SS and Tikhomorov SA (1989) 2 - So fluorescence and transient S Sq absorption ofo//-tm s-/3-carotenein solid and liquid solutions. Photochem Photobiol, A Chemistry 46 315-322 Bouwman W, Jones A, Phillips D, Thibodeau P, Friel C and Christensen R (1990) Fluorescence of gaseous tetraenes and pentaenes. J Phys Chem 94 7429-7434 Bredas JL, Sdbey R, Boudreaux DS and Chance RR (1983) Chain-length dependence of electronic and electrochemical properties of conjugated systems Polyacetylene, polyphenylene, polythiophene, and poly pyrrole. J Am Chem Soc 105 6555-6559... 

We have already reported soluble light-emitting poly(2,5-dialkoxy-p-phenylene vinylene), RO-PPV, and its side chain length dependence of fluorescence intensity(9). 

There is a lot of interest in microemulsions as is shown by this book [94] and by recent pubHcations on microemulsion models [95, 96], as well as oil chain length dependence [97] and the use of poly(ethylene glycol) (PEG) and microemulsions for pharmaceutical purposes [98, 99]. Microemulsions are used in many industrial appHcations [100], especially within the area of cosmetics and detergents [101] as well as in pharmaceutical applications [102] one of the more important ones being as drug-delivery systems [103-112]. 

K. Kaneto, W. Y. Lim, W. Takashima, T. Endo and M. Rikukawa. Alkyl chain length dependence of field-effect mobilities in regioreguiar poly(3-alkylthiophene) films. Jpn. J. Appl. Phys., Part 2 39(8B), L872-L874 (2000). 

Contrary to the dissociation rate constant, the recombination rate constant exhibits a very high chain-length dependence where fee for the macroradical is lower than fee for the model radical. For instance, fee for styryl radical and SGI is 4.6 X 10 Lmol s at 120 °C, whereas a 10-fold decrease was observed for the polystyryl radical (5.3 x 10 Lmol" s at 120 "C). The same trend was found for acrylate/SGl sys-tem. In the case of poly(methyl methacrylate) (PMMA) macroradicals and SGI, the fee value decreased by 2 orders of magnitude compared to the model radical. This result was assigned to a strong penultimate effect which also increased the dissociation rate constant but to a lower extent. ... 

Figure 1. Oligomer GPC of poly(phenylphenylene vinylene) with chain length dependent UV/VIS spectra...

Zhao P, Cheng XX, Liu GM, Zhang GZ (2010) Interaction of hydrophobically end-capped poly(ethylene glycol) with phospholipid vesicles The hydrocarbon end-chain length dependence. J Phys Chem B 114 1271-1276... 

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