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Issue 33, 2016
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Electronic relaxation dynamics of PCDA-PDA studied by transient absorption spectroscopy

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Abstract

Photo-curable polymers originating from 10,12-pentacosadiynoic acid (PCDA-PDA) are commonly used polydiacetylenes (PDAs). PCDA-PDA exhibits thermochromic properties undergoing a unique colorimetric transition from blue to red as the temperature is increased from low to high. In this work, we have carefully studied the temperature-dependent optical properties of PCDA-PDA by using UV-visible absorption, FTIR, Raman, and transient absorption (TA) spectroscopy in combination with quantum chemical calculations. Temperature-dependent UV-visible absorption spectra indicate that PCDA-PDA exhibits reversible thermochromic properties up to 60 °C and its thermochromic properties become irreversible above 60 °C. Such distinct thermochromic properties are also manifested in TA signals so that the electronically excited PCDA-PDA relaxes to the ground state via an intermediate state at 20 °C (blue form) but it relaxes directly back to the ground state at 80 °C (red form). The electronic relaxation dynamics of PCDA-PDA are comprehensively analyzed based on different kinetic models by using the global fitting analysis method. The intermediate state in the blue form of PCDA-PDA is clearly found to be responsible for fluorescence quenching. FTIR and Raman spectroscopy and quantum chemical calculations confirm that the H-bonds between the carboxylic acid groups in PCDA-PDA are broken at high temperatures leading to an irreversible structural change of PCDA-PDA.

Graphical abstract: Electronic relaxation dynamics of PCDA-PDA studied by transient absorption spectroscopy

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Publication details

The article was received on 03 Jun 2016, accepted on 23 Jul 2016 and first published on 28 Jul 2016


Article type: Paper
DOI: 10.1039/C6CP03858A
Phys. Chem. Chem. Phys., 2016,18, 23096-23104

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    Electronic relaxation dynamics of PCDA-PDA studied by transient absorption spectroscopy

    J. F. Joung, J. Baek, Y. Kim, S. Lee, M. H. Kim, J. Yoon and S. Park, Phys. Chem. Chem. Phys., 2016, 18, 23096
    DOI: 10.1039/C6CP03858A

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