Unveiling thermal transitions of polymers in subnanometre pores

The thermal transitions of confined polymers are important for the application of polymers in molecular scale devices and advanced nanotechnology. However, thermal transitions of ultrathin polymer assemblies confined in subnanometre spaces are poorly understood. In this study, we show that incorporation of polyethylene glycol (PEG) into nanochannels of porous coordination polymers (PCPs) enabled observation of thermal transitions of the chain assemblies by differential scanning calorimetry. The pore size and surface functionality of PCPs can be tailored to study the transition behaviour of confined polymers. The transition temperature of PEG in PCPs was determined by manipulating the pore size and the pore–polymer interactions. It is also striking that the transition temperature of the confined PEG decreased as the molecular weight of PEG increased

Study of biodegradable starch/polycaprolactone blends by solid-state NMR methods

International audienc

Comparison between theoretical and experimental results in 3D dosimetry for external radiotherapy.

International audienc

Monte Carlo simulation of energy spectra in water phantom from electron beams.

International audienc

High-resolution solid-state NMR study of isotactic polypropylenes

The high-resolution solid-state 13C NMR spectra were recorded for metallocene (m) and Ziegler-Natta (ZN) isotactic polypropylenes (iPP) in pelletized form using cross polarization (CP) and magic angle spinning (MAS) techniques within the temperature range of 20–160°C. Besides the CP MAS experiments also the MAS 13C NMR spectra (without CP), MAS 1H NMR spectra and rotating frame spin-lattice relaxation times T1ρ (13C) were measured at elevated temperatures. With the rise of temperature the splitting of CH2, CH and CH3 signals into two components was detected in 13C NMR spectra and assigned to amorphous and crystalline phases. The temperature dependences of chemical shifts and integral intensities obtained from the deconvoluted spectra provided information on the main chain and CH3 groups motions in amorphous and crystalline regions of studied samples. While T1ρ (13C) values show that the rate of segmental motion in amorphous regions in m-iPP and ZN-iPP is virtually the same, larger linewidths in 13C and 1H NMR spectra indicate somewhat larger restraints of the motion in amorphous regions of ZN-iPP