Tunable Mechano-responsive Color-Change Properties of Organic Layered Material by Intercalation  Yukiko Ishijima, Hiroaki Imai, Yuya Oaki  Chem  Volume 3, Issue 3, Pages 509-521 (September 2017) DOI: 10.1016/j.chempr.2017.05.013 Copyright © 2017 Elsevier Inc. Terms and Conditions

Chem 2017 3, 509-521DOI: (10.1016/j.chempr.2017.05.013) Copyright © 2017 Elsevier Inc. Terms and Conditions

Figure 1 Schematic Illustration of Organic Layered Composites with Tunable Stimuli-Responsive Color-Change Properties (A) Layered crystal structure of PCDA monomer. (B) Layered composite after intercalation of the guest amines and subsequent topochemical polymerization. (C) Temperature- and mechano-responsive color-change behavior of amine-intercalated PDA. Chem 2017 3, 509-521DOI: (10.1016/j.chempr.2017.05.013) Copyright © 2017 Elsevier Inc. Terms and Conditions

Figure 2 Layered Crystal Structure of the Amine-Intercalated PCDA (A) XRD pattern of pristine PCDA (i), PCDA-C8-NH2 (ii), and PCDA-C8-(NH2)2 (iii). (B) Expanded interlayer distance of amine-intercalated PCDA, such as d0 for PCDA-Cn-(NH2)2 (triangles) and 2d0 for PCDA-Cn-NH2 (circles), with changes in the alkyl-chain length (carbon number n of Cn). Detailed data are listed in Table S1 and Figure S1. (C–E) Schematic illustrations of the layered crystal structure of pristine PCDA (C), PCDA-Cn-NH2 (D), and PCDA-Cn-(NH2)2 (E). Chem 2017 3, 509-521DOI: (10.1016/j.chempr.2017.05.013) Copyright © 2017 Elsevier Inc. Terms and Conditions

Figure 3 Temperature-Responsive Color-Change Properties of the Amine-Intercalated PDA for Quantitative Characterization of Stimuli Responsivity (A) Selected photographs of PDA, PDA-Cn-NH2 (n = 8, 12, 16), and PDA-Cn-(NH2)2 (n = 4, 8, 12) with heating. The photographs of the other samples are shown in Figure S3. (B and C) UV-vis spectra of PDA (B) and PDA-C10-NH2 (C) with heating. (D) Relationship between the temperature and the x value for PDA-C8-NH2. x and Δx represent the intensity of the red color and the overall color change with heating, respectively. Ttrs is defined as the temperature to achieve 0.5Δx. (E) Relationship between Ttrs and the alkyl-chain length of PDA-CnNH2 and PDA-Cn(NH2)2 samples. See also Figure S3. Chem 2017 3, 509-521DOI: (10.1016/j.chempr.2017.05.013) Copyright © 2017 Elsevier Inc. Terms and Conditions

Figure 4 Mechano-responsive Color-Change Properties for Visualization of the Accumulated Mechanical Stress (A) Schematic illustration of the experimental setup for characterization of the mechano-responsivity. The rubbing was performed on the different PDA-Cn-NH2 samples. (B) Photographs of PDA, PDA-C8-NH2, PDA-C12-NH2, and PDA-C16-NH2 at ΣN = 0, 50, 100, 150, 200. (C) Relationship between ΣN and the x value of PDA, PDA-C8-NH2, PDA-C12-NH2, and PDA-C16-NH2. (D) Relationship between ΣN and the x value of PDA, PDA-C8-NH2, and PDA-C8-(NH2)2. (E and F) UV-vis spectra of PDA (E) and PDA-C8-NH2 (F) set on paper before and after rubbing. Because the powdered sample was mounted on paper, the stress induced a slight peak shift from the original PDA and PDA-C8-NH2 samples before rubbing. (G) Schematic illustration of the experimental setup for memory and visualization of ΣN by the color of PDA-C10-NH2. (H) Photographs of PDA-C10-NH2 on the first, second, third, and fourth days. The number in the photograph means the number of rubbings (N) on the corresponding day. ΣNf = 120 was eventually performed on the same four samples with a different history. (I) Relationship between the day and the x value of entries (i)–(iv). (J) Relationship between the ΣN and the x value of entries (i)–(iv). See also Movies S1 and S2. Chem 2017 3, 509-521DOI: (10.1016/j.chempr.2017.05.013) Copyright © 2017 Elsevier Inc. Terms and Conditions

Figure 5 Visualization of the Accumulated Mechanical Stress between the Rotational Parts (A) Schematic illustration of the experimental setup. (B) Photographs of PDA, PDA-C8NH2, PDA-C12-NH2, and PDA-C16-NH2 at a specific time (min) after rotation of the rollers. (C) Relationship between the rotation time and the x value for PDA, PDA-C8NH2, PDA-C12-NH2, and PDA-C16-NH2. Chem 2017 3, 509-521DOI: (10.1016/j.chempr.2017.05.013) Copyright © 2017 Elsevier Inc. Terms and Conditions