Development of a Simultaneous SANS/FTIR Measuring System

Abstract

A novel method for the simultaneous measurement of smallangle neutron scattering and Fourier transform infrared spectroscopy (SANS/FTIR) has been developed. The method was realized by building a device consisting of a portable FTIR spectrometer and an optical system that allows both a neutron beam and an infrared beam to pass through a sample coaxially. The device was installed on a small-angle neutron diffractometer, KWS2 of the Jülich Centre for Neutron Science (JCNS) outstation at Heinz Maier-Leibnitz Center (MLZ) in Garching, Germany. In order to check the performance of this measuring system, the structural changes in a cocrystal of syndiotactic polystyrene with triethylene glycol dimethyl ether, were followed during the course of heating.Small-angle neutron scattering (SANS) is a powerful and convenient method to investigate the higher-order structure of static polymer systems. Owing to technological developments in instruments such as detectors and neutron guides, SANS has extended its presence, even to research concerning timedependent structural evolution.The scattering pattern of SANS is determined by the scattering length density (SLD) profile of the object under study, and therefore, it is of great difficulty to derive the sole solution for the arrangement of constituent components from the scattering pattern of SANS. Accordingly, if a system of interest is a multicomponent one, the interpretation of the time-dependent changes in SANS profile is not easy. There are usually several alternatives to explain the variations in the SANS profile, and it is laborious to select an option from them. 1,2 It is desirable to obtain two or more different kinds of structural information simultaneously from the same sample, which would drastically reduce ambiguities in interpretation. Vibrational spectroscopy has been employed as a complementary tool to X-ray and neutron diffractometry for investigating the structure of polymer systems. Simultaneous analyzes by X-ray scattering and Fourier transform infrared spectroscopy (FTIR) have been developed so far. 36 We expect that the combination of SANS with FTIR would also produce a fruitful methodology for such a simultaneous measurement system. Owing to a high-throughput optical system, a highly sensitive detector, and advanced hardware and software design, it is easy to follow the time-evolution of infrared spectra with a compact FTIR spectrometer. 7,8 Such flexibility of FTIR has been employed also for simultaneous measurement with differential scanning calorimetry (DSC). 9,10 In this study, we tried to establish the simultaneous SANS/ FTIR measurement protocol. For this purpose, a device consisting of a portable FTIR spectrometer and an optical system, which allows a sample to be irradiated with neutron and infrared beams simultaneously, was developed and installed on a smallangle neutron diffractometer. In the proof-of-concept experiment described here, we followed the structural changes on heating a crystalline complex system of syndiotactic polystyrene (sPS) with...

Simultaneous small-angle neutron scattering and Fourier transform infrared spectroscopic measurements on cocrystals of syndiotactic polystyrene with polyethylene glycol dimethyl ethers

“…Similarly, the combination of FTIR spectroscopy with SANS would produce a fruitful methodology for such a simultaneous measurement system. In a previous study (Kaneko et al, 2015), we tested the simultaneous experimental setup on an sPS cocrystal system and confirmed its usefulness; the information obtained from the FTIR spectrum greatly helped us to interpret the SANS profile changes.…”

“…crystalline lamellae with a repeat period of about 100 Å appear along the meridian. The intensity of the lamellar reflection increases remarkably with temperature, in dramatic contrast to the sPS/TEGDME cocrystal whose lamellar reflections wane as the temperature increases (Kaneko et al, 2015). It follows that there is an evident difference in the temperature dependence of the guest distribution between the d-sPS/TEGDME and d-sPS/PEGDME500 cocrystals, since the distribution of protonated guest molecules is the main factor to determine the scattering length density (SLD) in the host d-sPS matrix.…”

“…It might be desirable to utilize the information of both overall molecular shape and local molecular structure of PEGs for approaching this issue. For this purpose, we have tried to apply a new measuring method, a simultaneous measurement technique combining small-angle neutron scattering (SANS) and Fourier-transform infrared (FTIR) spectroscopy that we developed recently (Kaneko et al, 2015), to the cocrystal system of sPS with PEGs.…”

“…Accordingly, the comparison of SANS and FTIR data between the lower-and higher-temperature regions would inform us about the structural features of PEG in the crystalline and amorphous regions. In the previous simultaneous SANS/FTIR study using a short polyethylene glycol dimethyl ether (PEGDME), triethyleneglycol dimethyl ether (TEGDME) with a molecular weight of 178, hardly any of the guest molecules remained in the amorphous region at elevated temperatures because of the high volatility (Kaneko et al, 2015). In response to this point, we employed a longer PEGDME with a molecular weight of about 500 (PEGDME500).…”

The Effects of Temperature and Humidity on the Microstructure of Sulfonated Syndiotactic–polystyrene Ionic Membranes

“…The low spectrum (black line) was acquired from the sPS-C60 composite membrane after casting from the common solution in h-toluene. Typical spectral features of δ-form of deuterated sPS [38] can be observed, such as the ring stretching and bending modes and backbone C-D and C-D 2 stretching in the region of 2300 to 2150 cm −1 (the range indicated by the green horizontal arrows) and the C=C stretching at around 1570 cm −1 [39]; while at short wavenumbers, between 500 and 550 cm −1 , the bands characteristics of the chain conformation of deuterated sPS in the δ-crystalline form are displayed. These features appear in all further spectra regardless of treatment procedure.…”