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Tham khảo tài liệu 'conductive polymers and plastics in industrial applications part 2', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Polyaniline from a Structural Perspective 15 subtle systematic variations throughout this intermediate HF-doping sequence. The 20 30o shoulder becomes much less pronounced while the 20 26o shoulder is ultimately identified as a distinguishable peak. The 995 mM sample scan is clearly different from all the preceding curves and indicates that addition HF uptake to give y 0.5 is associated with a discrete change to another structural phase. In this case the scattering profile bears a strong resemblance to the H2SO4-doped PANI-ES results of Moon et al.12 We note that throughout the entire processing sequence of samples in Figure 4 there appears to be a monotonic decrease in the proportion of scattering which can be attributed to crystalline regions of the films. Moreover these remaining peaks also appear to broaden somewhat. This general trend suggests that c-PANI is fragile and that the continued structural variations irreversibly lower the relative crystallinity. There are other important scattering features that can be resolved. The HCl-ES scan of Figure 3 contains distinctive variations in the widths and shapes of the resolved peaks. Naively one expects that simple crystalline polymers tend to produce scattering peaks whose full-width at half-maximum are nearly independent of the crystal orientation and broaden only slightly with increasing 20. In this sample the two peaks located near 20 26o and 28o are much narrower than any other resolved peaks including those at lower angles. While an anisotropic crystal habit may play a role in this result a more likely possibility is that these other peaks are comprised of at least two or more superimposed scattering peaks from a low-symmetry unit cell. Hence a simple d-spacing identification is somewhat deceptive although we include this in Table 1. Before introducing possible structural models for the aforementioned results it is first necessary to demonstrate the significance of incorporating water uptake17 into any .
