We report synthesis of amphoteric microgels by copolymerization of N-vinylcaprolactam (VCL), itaconic acid dimethyl ester (IADME), and vinylimidazole (VIm) in the precipitation−polymerization process. After hydrolysis of ester groups of IADME, component microgels contain acidic and basic groups in their structure. Proton high-resolution transverse magnetization relaxation under magic angle sample spinning (MAS) was used to measure the dynamic heterogeneity corroborated with the chemical structure of a multicomponent amphoteric microgel. NMR results indicate that itaconic acid groups (originated from hydrolyzed IADME component) are localized mostly in the microgel core. The core−shell morphology of poly(N-vinylcaprolactam)-based microgels was suggested with carboxylic acid groups in the core and imidazole groups in the shell. The variation of the IADME and VIm content in microgel structure allows varying microgel charge and swelling degree in basic and acidic pH, respectively. Obtained amphoteric microgels exhibit narrow size distribution and superior colloidal stability.

Morphology, phase composition, and molecular mobility for a series of semicommercial gel-spun UHMWPE fibers were studied using a combination of WAXS, SAXS, and 1 H solid-state NMR methods. The fibers show uncommon for this type of fibers decrease in the break load with increasing draw ratio, whereas their modulus and the tenacity reach very high ultimate values. The X-ray and NMR methods have provided complementary information about the fiber morphology and structural reorganizations occurring at the final stage of the fiber drawing. The results suggest that the fiber morphology can be described by a mixture of crystalline fibrils with long period of ∼35À45 nm, as shown by SAXS, and large, so-called, chain-extended crystals. The presence of large crystals with embedded defects is shown by NMR. The drawing causes increase in the crystallinity from ∼89 to ∼96 wt % and in chain orientation, while the long period of fibrils and the break load of fibers surprisingly decrease. The decrease in the long period with the drawing could indicate a partial reorganization of the amorphous phase and/or some fragmentation of the fibrils, while the decrease in the break load could correspond to a decrease in number of load-bearing chains. A disorder of the crystals and a small increase in chain mobility in the constrained amorphous fraction is also observed with increasing the drawing. Approximately 1 wt % of the chain fragments in the amorphous fraction has a high molecular mobility. It is assumed that these chain fragments reside in nanovoids, the presence of which was shown previously by a 129 Xe NMR study on the same fibers. The role of α-crystalline relaxation in structural reorganizations during fiber drawing is also discussed.

Hyperbranched polyethoxysiloxanes were prepared via a one-pot synthetic route based on a condensation reaction of tetraethoxysilane with acetic anhydride in the presence of an organotitanium catalyst. Volatile compounds can be fully removed using a thin-film evaporator. According to size-exclusion chromatography and viscosity measurements, the average molecular weight as well as the molecular weight distribution of the products increased exponentially by increasing the molar ratio of acetic anhydride to tetraethoxysilane from 1.0 to 1.2. At the molar ratio 1.3, a solid gel was formed. The liquid products are stable and hydrophobic; they are miscible with most organic solvents. 29Si NMR spectroscopy and MALDI-ToF mass spectrometry show that they have a hyperbranched structure with additional internal loop formation.

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Thermal denaturation of hydrated keratin in wool was investigated by NMR using 1H wide-line spectra to obtain the phase composition and 1H spin-diffusion experiments using a double-quantum filter to obtain the domain sizes for the wool fibers. The denaturation process detected by DSC takes place for wool fibers in deuterated water in the temperature range 140-144 degreeC. The phase composition measured by 1H wide line NMR spectra reveals a rigid, semirigid and an amorphous phase for temperatures in the range 25-160 degreeC. A dramatic change in the phase composition was detected around 142 degreeC, corresponding to the denaturation temperature. The morphological domain sizes measured by 1H spin-diffusion NMR experiments were obtain from the solutions of the spin-diffusion equations for two-dimensional rectangular and cylindrical morphologies. The keratin mobility gradient in the interfacial region at different denaturation temperatures was measured from the 1H spin-diffusion data. A qualitative model describing the denaturation process of hydrated keratin protein was developed that explains the changes in domain thickness, spin diffusivities, phase composition, and thermodynamic parameters.