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A Unified Material Description for Light Induced Deformation in Azobenzene Polymers.

Bin J, Oates WS - Sci Rep (2015)

Bottom Line: It is shown that dipole forces strongly respond to polarized light in contrast to higher order quadrupole forces that are often used to describe surface relief grating deformation through a field gradient constitutive law.The modeling results and comparisons with a broad range of photomechanical data in the literature suggest that the molecular structure of the azobenzene monomers dramatically influences the photostrictive behavior.The results provide important insight for designing azobenzene monomers within a polymer network to achieve enhanced photo-responsive deformation.

View Article: PubMed Central - PubMed

Affiliation: Florida Center for Advanced Aero Propulsion (FCAAP), Department of Mechanical Engineering, Florida State University. Tallahassee, FL, 32310, USA.

ABSTRACT
Complex light-matter interactions in azobenzene polymers have limited our understanding of how photoisomerization induces deformation as a function of the underlying polymer network and form of the light excitation. A unified modeling framework is formulated to advance the understanding of surface deformation and bulk deformation of polymer films that are controlled by linear or circularly polarized light or vortex beams. It is shown that dipole forces strongly respond to polarized light in contrast to higher order quadrupole forces that are often used to describe surface relief grating deformation through a field gradient constitutive law. The modeling results and comparisons with a broad range of photomechanical data in the literature suggest that the molecular structure of the azobenzene monomers dramatically influences the photostrictive behavior. The results provide important insight for designing azobenzene monomers within a polymer network to achieve enhanced photo-responsive deformation.

No MeSH data available.


Iso-contours of the stored energy density for the trans state  and the dipole interaction energy (PiEi) from I, which is given by.(a) Isotropic energy with no light present. (b) Energy surface when polarized light E is applied in the  direction. The trans vectors tend to line up in a direction orthogonal to the light polarization as illustrated by the doughnut iso-energy surface.
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f2: Iso-contours of the stored energy density for the trans state and the dipole interaction energy (PiEi) from I, which is given by.(a) Isotropic energy with no light present. (b) Energy surface when polarized light E is applied in the direction. The trans vectors tend to line up in a direction orthogonal to the light polarization as illustrated by the doughnut iso-energy surface.

Mentions: The driving force for trans-cis-trans photoisomerization is illustrated in Fig. 2 for the low energy trans state prior to photoisomerization. This plot includes both the stored energy of the trans state from Eq. (3) and the electrostatic interaction energy of the trans charge density from Eq. (1); see the supplemental text for details. The electrostatic part of the Lagrangian interaction density is qϕ where ϕ is the electrostatic potential38. This energy density can be written in terms of the electric field and polarization as denoted by . The energy plot illustrating the driving force for trans-cis-trans photoisomerization for the trans azobenzene coordinate is then . Figure 2(a) illustrates the zero light case where the trans state can orient into any direction; shown as an iso-energy, spherical surface in space. When linearly polarized light is aligned in the direction, for example, a driving force for the trans vector to reorient to any direction in the plane is created as shown by a doughnut of constant energy in these directions. The iso-energy doughnut in Fig. 2(b) contains this minimum energy radius on the plane.


A Unified Material Description for Light Induced Deformation in Azobenzene Polymers.

Bin J, Oates WS - Sci Rep (2015)

Iso-contours of the stored energy density for the trans state  and the dipole interaction energy (PiEi) from I, which is given by.(a) Isotropic energy with no light present. (b) Energy surface when polarized light E is applied in the  direction. The trans vectors tend to line up in a direction orthogonal to the light polarization as illustrated by the doughnut iso-energy surface.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4594130&req=5

f2: Iso-contours of the stored energy density for the trans state and the dipole interaction energy (PiEi) from I, which is given by.(a) Isotropic energy with no light present. (b) Energy surface when polarized light E is applied in the direction. The trans vectors tend to line up in a direction orthogonal to the light polarization as illustrated by the doughnut iso-energy surface.
Mentions: The driving force for trans-cis-trans photoisomerization is illustrated in Fig. 2 for the low energy trans state prior to photoisomerization. This plot includes both the stored energy of the trans state from Eq. (3) and the electrostatic interaction energy of the trans charge density from Eq. (1); see the supplemental text for details. The electrostatic part of the Lagrangian interaction density is qϕ where ϕ is the electrostatic potential38. This energy density can be written in terms of the electric field and polarization as denoted by . The energy plot illustrating the driving force for trans-cis-trans photoisomerization for the trans azobenzene coordinate is then . Figure 2(a) illustrates the zero light case where the trans state can orient into any direction; shown as an iso-energy, spherical surface in space. When linearly polarized light is aligned in the direction, for example, a driving force for the trans vector to reorient to any direction in the plane is created as shown by a doughnut of constant energy in these directions. The iso-energy doughnut in Fig. 2(b) contains this minimum energy radius on the plane.

Bottom Line: It is shown that dipole forces strongly respond to polarized light in contrast to higher order quadrupole forces that are often used to describe surface relief grating deformation through a field gradient constitutive law.The modeling results and comparisons with a broad range of photomechanical data in the literature suggest that the molecular structure of the azobenzene monomers dramatically influences the photostrictive behavior.The results provide important insight for designing azobenzene monomers within a polymer network to achieve enhanced photo-responsive deformation.

View Article: PubMed Central - PubMed

Affiliation: Florida Center for Advanced Aero Propulsion (FCAAP), Department of Mechanical Engineering, Florida State University. Tallahassee, FL, 32310, USA.

ABSTRACT
Complex light-matter interactions in azobenzene polymers have limited our understanding of how photoisomerization induces deformation as a function of the underlying polymer network and form of the light excitation. A unified modeling framework is formulated to advance the understanding of surface deformation and bulk deformation of polymer films that are controlled by linear or circularly polarized light or vortex beams. It is shown that dipole forces strongly respond to polarized light in contrast to higher order quadrupole forces that are often used to describe surface relief grating deformation through a field gradient constitutive law. The modeling results and comparisons with a broad range of photomechanical data in the literature suggest that the molecular structure of the azobenzene monomers dramatically influences the photostrictive behavior. The results provide important insight for designing azobenzene monomers within a polymer network to achieve enhanced photo-responsive deformation.

No MeSH data available.