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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Photoactive polyurethanes based on 2,2 `-dihydroxyazobenzene fluorescent segments

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Paiva, Germana M. S. [1] ; Duarte, Luis G. T. A. [1] ; Faleiros, Marcelo M. [1] ; Atvars, Teresa D. Z. [1] ; Felisberti, Maria Isabel [1]
Total Authors: 5
[1] Univ Estadual Campinas, Inst Chem, POB 6154, BR-13084971 Campinas, SP - Brazil
Total Affiliations: 1
Document type: Journal article
Web of Science Citations: 0

This article presents the synthesis and structural, thermal and dynamic mechanical characterization of segmented polyurethane - PCLDHAB - based on poly(caprolactone)-diol (PCL-diol) as a flexible segment, and polyurethane-diol (PU-diol) as a rigid segment based on 2,2'-dihydroxyazobenzene (2,2'-DHAB). While the precursors PU-diol and PCL-diol are rigid and waxy materials, respectively, PCLDHAB is a flexible, semi-crystalline polymer, which has a heterogeneous amorphous phase. To better understand the absorption spectra of the polyurethanes, theoretical predictions by DFT and TD-DFT of a model molecule in DMF (implicitly added) were carried out. The model molecule was a fragment of the hard segment of the polyurethane's chain, containing one 2,2'-DHAB and two 4'-isocyanate-4'-methylbenzene fragments, bonded to each other by carbamate bonds, the 4-isocyanate-4'-metylbenzene-alt-2,2'-dihydroxyazoben zene. Similar to 2,2'-DHAB, PU-diol and PCLDHAB do not show photoisomerization, however they emit fluorescence. 2,2'-DHAB segments in the polyurethane chains present different conformations with distinct spectroscopic characteristics. However, the conformer's proportion in the polymer chains differs from the 2,2'-DHAB monomers in DMF solution. 2,2'-DHAB emits in two ranges in the UV-vis spectrum while its polyurethanes emit in three ranges, covering a broader wavelength range from ultraviolet to visible. (C) 2021 Elsevier B.V. All rights reserved. (AU)

FAPESP's process: 15/25406-5 - Organizing matter: colloids formed by association of surfactants, polymers and nanoparticles
Grantee:Watson Loh
Support Opportunities: Research Projects - Thematic Grants
FAPESP's process: 13/16245-2 - Photophysical properties of thin films of conjugated polymers
Grantee:Teresa Dib Zambon Atvars
Support Opportunities: Regular Research Grants
FAPESP's process: 15/08541-6 - Nuclear magnetic resonance spectroscopy: beyond molecular structure assignment
Grantee:Claudio Francisco Tormena
Support Opportunities: Research Projects - Thematic Grants
FAPESP's process: 16/11197-8 - Polyurethanes tri- and tetra blocks functionalized with azo group: synthesis, characterization and evaluation of potential as photo-responsive materials
Grantee:Germana Maria Santos Paiva
Support Opportunities: Scholarships in Brazil - Doctorate