Dynamic heterogeneity is an active field of glass-transition research. The length scale of this heterogeneity is called the characteristic length. It can be calculated from complex heat capacity curves in the equilibrium liquid or from dynamic calorimetry curves corrected with regard to nonequilibrium. No molecular parameters or microscopic models are necessary for obtaining the length. We report the characteristic length near glass temperature for about 30 glass formers including small-molecule liquids, polymers, silicate glasses, a metallic glass, a liquid crystal, and a plastic crystal. The lengths are between 1.0 and 3.5 nm with certain cumulations between 1.0 and 2.0 nm and between 2.5 and 3.5 nm. To try a correlation to other properties, we find that at least two should be included, e.g., Angell's fragility and the distance of T g from the crossover temperature, T c .

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We show that the crystal orientation in polymer nanotubes and nanorods inside porous templates is controlled by the kinetics of nucleation and growth under 2D confinement. Two clear limiting cases are identified: In separated nanostructures, any crystal orientation allowing the growth of lamellar crystals along the pores appears statistically. If a bulklike surface film connects the nanostructures, macroscopic arrays with uniform crystal orientation are obtained, in which the dominant growth direction of the crystals is aligned with the long axes of the pores of the template.

Shear data in the temperature range from −145 °C to the flow zone are presented for the poly(n-alkyl methacrylate)s from methyl (C = 1) to lauryl (C = 12). Three qualitatively different glass transitions are observed in the shear curves at 10 rad/s:  (i) the conventional α process in the C < 5 members, (ii) the high temperature a process in the C > 5 members, and (iii) an additional polyethylene-like glass transition, αPE, in the C ≥ 3 members. All three processes depend systematically on side chain length. Two alternative empirical pictures for the coexistence of two glass transitions are discussed:  (a) a static nanophase separation between main chains and side chains and (b) a dynamic heterogeneity with two different time and length scales.

A series of regiorandom poly(3-alkylthiophenes) [P3ATs] with 4 ≤ C ≤ 12 alkyl carbons per side chain are studied by shear, calorimetry, X-ray scattering techniques, and infrared spectroscopy. We show that the tendency of alkyl groups to segregate in small alkyl nanodomains is a common feature of semicrystalline and amorphous members of this series. Semicrystalline poly(3-dodecylthiophene) (C = 12) samples show a pronounced lamellar structure with a coherence length of about 150 Å, corresponding to staples of main chain and alkyl nanodomains comparable to the findings for regioregular P3ATs, while the alkyl nanodomains in amorphous P3ATs have more irregular shape and boundaries. An additional relaxation process αPE, which is related to the dynamics of CH2 units in the alkyl nanodomains, appears in amorphous samples with C ≥ 6. Its frequency temperature dependence is very similar to that of the αPE process found in other side-chain polymers containing alkyl groups with identical length. This is a strong argument supporting the idea that main chains and alkyl groups separate in amorphous systems. Another interesting finding is the appearance of three distinct melting peaks for regiorandom poly(3-dodecylthiophene) [P3DDT] at temperatures between −10 and 50 °C. Isothermal crystallization experiments are performed, and possible reasons for the appearance of three distinct melting peaks are considered. Similarities and differences between regiorandom and regioregular P3ATs in the semicrystalline state are described and discussed on the basis of their microstructure.