Observation of molecular motions in polymer thin films by laboratory grazing incidence diffracted X-ray blinking

Abstract

Research on polymer surfaces has shown that the mobilities of polymer chains, which affect the aggregation state and thus the physical properties of the material, differ between the surface and bulk. However, the mobilities of the surface polymers have not been fully characterized. Therefore, we propose a time-resolved method for evaluating surface mobility. This measurement scheme is called grazing incidence diffracted X-ray blinking (GI-DXB) and can be used to evaluate the molecular motions occurring at polymer surfaces by continuously measuring X-ray diffraction patterns near the total reflection angle over small time periods. In this study, the crystallized polymer poly{2-(perfluorooctyl)ethyl acrylate}(PC8FA) was measured. The decay constants, which are indexes of molecular motions, were calculated to be 3.98 × 10−3 s−1 for the fluoroalkyl groups in the side chains observed along the in-plane direction and 3.36 × 10−3 s−1 for the lamellar structure observed along the out-of-plane direction when 2000 diffraction profiles of 500 ms were recorded and the incident angle was 0.07°. In contrast, transmission DXB indicated decay constants of 2.63 × 10−3 s−1 for the side chains and 2.87 × 10−3 s−1 for the lamellar structures. These results suggested that the PC8FA surface is mobile, because a larger decay constant indicates a higher mobility. GI-DXB can be used to measure surface dynamics. The authors contend that GI-DXB is a highly versatile tool because it allows the evaluation of local motions with a laboratory X-ray system, and these motions cannot be detected by conventional surface analyses. This measurement scheme may facilitate the development of high-performance polymers and discovery of new physical properties.

Diffracted X-ray Tracking for Observing the Internal Motions of Individual Protein Molecules and Its Extended Methodologies

“…Since the motion is not in one direction but in random motion, the observation of the diffraction point in motion using monochromatic X-rays, which have only a narrow energy range, causes the appearance of a blinking diffraction point. This concept is the principle of the diffracted X-ray blinking method DXB, as shown in Figure 18 [45][46][47][48][49][50][51][52][53][54]. Unlike DXT, where the exact direction of motion can be determined, the speed of motion can be monitored; the X-ray blinking phenomenon is similar to the X-ray Photon Correlation Spectroscopy: XPCS analysis method [55,56], which is an X-ray technique.…”

“…In the future, in vivo DXT/DXB will likely have an even greater contribution to the effective elucidation of biological phenomena. Many technological advances can also be expected [53,54,[57][58][59]. For example, this technology is expected to be adapted to electron and neutron beams instead of X-rays.…”

Electrochemistry of Thin Films and Nanostructured Materials

“…For instance, Au films less than 300 nm thick covering copper and bronze statues and jewelry have been found in ancient tombs in the Pyramid of Djoser (Netjerykhet), built by the second King of the Third Dynasty, Old Kingdom (from 2667 to 2648 BC) in Saqqara [3]. Since then, humanity has learned not only how to obtain thin films of metals, metal oxides, various nitrides, carbides, semiconductors, and polymers [4][5][6][7][8], but also to study and control their chemical, optical, electrical, and mechanical properties, which differ considerably from the corresponding bulk materials [9][10][11][12][13]. The film properties can be precisely controlled by changing the thickness, which is a great benefit for thin film technologies and applications.…”

The Blinking of Small-Angle X-ray Scattering Reveals the Degradation Process of Protein Crystals at Microsecond Timescale

“…In addition, this method can be applicable to the dynamics of crystalline objects themselves [14]. Remarkably, DXB can not only measure the diffracted X-rays of crystalline objects but also the X-ray haloes of non-crystalline ones, which enables us to assess the dynamics of polymeric materials [15,16]. Here, we examined a combined use of DXB and SAXS methods for a lysozyme single-crystal to obtain information about its domain dynamics caused by X-ray irradiation, which could be correlated with the X-ray induced damage.…”