Polymer side chain mobility

Exposure of corona treated surfaces to high levels of ambient humidity and temperature accelerates polymer side chain mobility and treatment degradation. Migration of slip additives can be accelerated and therefore also needs to be taken into consideration when optimizing a process solution for converting corona treated substrates. 

S. Tazuke, R. Kun Guo, and R. Hayashe, How does the polymer main chain influence the side-chain mobility A fluorescence probe study by means of twisted intramolecular charge-transfer phenomena, Macromolecules 21, 1046 (1988). 

The structure of this interface determines fhe sfabilify of PEMs, the state of water, the strength of interactions in the polymer/water/ion system, the vibration modes of side chains, and the mobilities of wafer molecules and protons. The charged polymer side chains contribute elastic ("entropic") and electrostatic terms to the free energy. This complicated inferfacial region thereby largely contributes to differences in performance of membranes wifh different chemical architectures. Indeed, the picture of a "polyelectro-lyfe brush" could be more insighttul than the picture of a well-separated hydrophobic or hydrophilic domain structure in order to rationalize such differences. ... 

A fourfold decrease in the IDIIM ratio was observed for the 5.3% peracetylated pyrenylmethyl polyethylenimine derivative in glycerol compared to methanol. The higher viscosity of the glycerol limits the mobility of the attached pyrene group necessary to form excimer, decreases the association rate, and hence lowers ID/IM. These samples at 77°C showed essentially no excimer emission. Clearly, diffusion of the pyrene moieties attached to the polymer side chains is necessary for excimer formation. 

The variation of the temperature interval of structure formation is also accounted for by the effect of side chain mobility on mesophase nucleation. The solutions of cholesterol-containing polymers with longer spacer groups have to be cooled further for mesophase nuclei to be formed. For instance, in a series of PChMO-n polymers the interval of structure formation is for PChMO-14 — 308-313 K, for PChMO-lO — 323-333 K and for PChMO-5 the internal structure is formed at even higher temperatures 187). 

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... 

The hole mobility in such blends is observed to increase with increasing polymer content (as one would intuitively expect) and then peaks at a ratio of 6 4 (MEH-PPV [60]PCBM) before falling. A similar set of results has also been obtained using poly[2-methoxy-5-(3, 7 -dimethyloctyloxy-p-phenylene vinylene)] (MDMO-PPV) (see Figure S.lOd) [59]. Although not mentioned at the time, this observation has since been explained by the intercalation of fullerene molecules between the polymer side chains and a subsequent extension of the polymer backbone [84—86]. This can explain why the hole mobility of PPViPCBM blends increases with increasing fiiHerene content... 

The effect on chiroptical and thermal properties due to the presence of achiral comonomers into polymer and its characterization in terms of side-chain mobility and grown hindrance was studied. The monomer (S)-MPAAP with triphenylmethyl methacrylate (TrMA) and an inactive fert-butyl methacrylate (fert-BMA) in different concentrations followed by radical copolymerization reaction. At different concentration of (S)-MPAAP co-units, the structures of the synthesized compounds poly [(S)-MPAAP-co- TrMA]s and poly[(5)-MPAAP-co-fcrf-BMA]s were investigated... 

Many of the properties of a polymer depend upon the presence or absence of crystallites. The factors that determine whether crystallinity occurs are known (see Chapter 2) and depend on the chemical structure of the polymer chain, e.g., chain mobility, tacticity, regularity and side-chain volume. Although polymers may satisfy the above requirements, other factors determine the morphology and size of crystallites. These include the rate of cooling from the melt to solid, stress and orientation applied during processing, impurities (catalyst and solvent residues), latent crystallites which have not melted (this is called self-nucleation). 

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