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Thermal isomerization of azo-benzene in PMMA probed by a pulsed low-energy positron beam

Algers, John LU ; Skeppstedt, V ; Sperr, P ; Egger, W and Maurer, Frans LU (2004) Positron Annihilation: Proceedings of the 13th International Conference on Positron Annihilation, ICPA-13 445-446. p.262-264
Abstract
Polymers containing the Azo-benzene group have attracted attention due to anticipated uses such as materials for data storage, membranes with controllable permeability and materials with changeable solubility [1,2]. These expectations are due to the change in shape and dipole moment of the Azo-compound when excited by photo isomerization from the trans-state to the cis-state by UV light of ca 360 nm. Films of copolymers of poly-methyl methacrylate (PMMA) containing 8 wt-% Azo-benzene were photo isomerized with a UV lamp and then measured as a function of time in a lowenergy positron beam. The observed changes in the lifetime parameters as a function of time were in agreement with the thermal isomerization (decay) of the cis-isomer as... (More)
Polymers containing the Azo-benzene group have attracted attention due to anticipated uses such as materials for data storage, membranes with controllable permeability and materials with changeable solubility [1,2]. These expectations are due to the change in shape and dipole moment of the Azo-compound when excited by photo isomerization from the trans-state to the cis-state by UV light of ca 360 nm. Films of copolymers of poly-methyl methacrylate (PMMA) containing 8 wt-% Azo-benzene were photo isomerized with a UV lamp and then measured as a function of time in a lowenergy positron beam. The observed changes in the lifetime parameters as a function of time were in agreement with the thermal isomerization (decay) of the cis-isomer as measured by conventional UV spectroscopy. The results show that positron lifetime spectra at low energy are sensitive for the cis-trans isomerization of the Azo-compound, suggesting trapping and annihilation of positrons at free volume sites around the Azo-benzene groups. (Less)
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author
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organization
publishing date
type
Chapter in Book/Report/Conference proceeding
publication status
published
subject
host publication
Materials Science Forum
volume
445-446
pages
262 - 264
publisher
Trans Tech Publications
conference name
Positron Annihilation: Proceedings of the 13th International Conference on Positron Annihilation, ICPA-13
conference location
Kyoto, Japan
conference dates
2003-09-07 - 2003-09-12
external identifiers
  • wos:000189406800076
  • scopus:3142781608
ISSN
0255-5476
language
English
LU publication?
yes
additional info
The information about affiliations in this record was updated in December 2015. The record was previously connected to the following departments: Polymer and Materials Chemistry (LTH) (011001041)
id
afc5302f-ed40-40ee-a514-91f761d23877 (old id 139537)
date added to LUP
2016-04-01 16:09:10
date last changed
2025-10-14 11:44:12
@inproceedings{afc5302f-ed40-40ee-a514-91f761d23877,
  abstract     = {{Polymers containing the Azo-benzene group have attracted attention due to anticipated uses such as materials for data storage, membranes with controllable permeability and materials with changeable solubility [1,2]. These expectations are due to the change in shape and dipole moment of the Azo-compound when excited by photo isomerization from the trans-state to the cis-state by UV light of ca 360 nm. Films of copolymers of poly-methyl methacrylate (PMMA) containing 8 wt-% Azo-benzene were photo isomerized with a UV lamp and then measured as a function of time in a lowenergy positron beam. The observed changes in the lifetime parameters as a function of time were in agreement with the thermal isomerization (decay) of the cis-isomer as measured by conventional UV spectroscopy. The results show that positron lifetime spectra at low energy are sensitive for the cis-trans isomerization of the Azo-compound, suggesting trapping and annihilation of positrons at free volume sites around the Azo-benzene groups.}},
  author       = {{Algers, John and Skeppstedt, V and Sperr, P and Egger, W and Maurer, Frans}},
  booktitle    = {{Materials Science Forum}},
  issn         = {{0255-5476}},
  language     = {{eng}},
  pages        = {{262--264}},
  publisher    = {{Trans Tech Publications}},
  title        = {{Thermal isomerization of azo-benzene in PMMA probed by a pulsed low-energy positron beam}},
  volume       = {{445-446}},
  year         = {{2004}},
}