Structural analysis of mold temperature dependence of polycarbonate by mid-infrared spectroscopy.

The mold temperature dependence of bisphenol A polycarbonate (BPAPC) in the view of changing the "flexed state" was investigated by mid-infrared spectroscopy combined with a previously developed thin sample preparation system. The differences in the samples of different mold temperatures were clearly detected. The structural changes in the flexed state of each mold temperature were analyzed by comparing the results using dielectric function analysis of different cutting procedures. Some structure parameters were associated with the contact angle of liquids on polymer plate. The evidence suggests that mold temperature and surface wettability affects the cohesive or entanglement state of polymers at the chemical structure level.

A new approach to investigate thin surface layers of polymers: fatigue analysis of polycarbonate.

A new technique to investigate chemical structures of very thin surface (mesoscopic scale) layers of polar polymers is proposed. The chemical structures and conformations of ∼100 nm-thick slabs that were obtained from a polymer surface were studied by infrared spectroscopy combined with a previously developed thin sample preparation system. The dielectric functions were calculated using oscillator models from reflection spectra of the slabs, which were cut with a diamond blade. The molecular movements caused by shear force perturbations after the cutting process ("flexed state") were observed. The technique was applied to analyze the changes in the chemical structure of bisphenol A polycarbonate (BPAPC) throughout a bending cyclic fatigue test. Three characteristic stages of structural changes in the flexed state under the cyclic fatigue test were observed. Our technique has the potential to clarify the intrinsic structures of solid polymers such as the degree of entanglement and the tendency for order or disorder caused by the surrounding chain interaction.

Infrared surface analysis using a newly developed thin-sample preparation system.

We developed a new sampling system, the Nano Catcher, for measuring the surface chemical structure of polymers or industrial products and we evaluated the performance of the system. The system can directly pick up surface species whose depth is on the order of approximately 100 nm and can easily provide a sample for a Fourier transform infrared (FT-IR) system without the necessity of passing it over to a measurement plate. The FT-IR reflection data obtained from the Nano Catcher were compared with those obtained using the attenuated total reflection (ATR) method and sampling by hand. Chemical structural analysis of a depth region from a few tens of nanometers to a few hundred nanometers can be directly performed using this system. Such depths are beyond the scope of conventional X-ray photoelectron spectroscopy (XPS) and ATR methods. We can expect the use of the Nano Catcher system to lead to a great improvement in the detection of signals of surface species in these depth regions.