&lt;title&gt;Mechanisms of light-induced orientation ordering of azobenzene-containing polymer molecules&lt;/title&gt;

Puchkovskaya, G. A.; Yaroshchuk, O.; Lindau, J.; Shans'ky, L. I.; Tereshchenko, A. G.

doi:10.1117/12.323687

Cited by 3 publications

(6 citation statements)

References 3 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Consequently, the negative Δ A in this region indicates a perpendicular reorientation of the alkyl groups in the side as well as main chains, as already reported by Kulinna and co-workers using selectively deuterated liquid crystalline polymers . The fact that the band due to the ester CO displays a negative sign in Δ A tells us that the flexible polyester backbones are critically affected by the photoreorientation of the azobenzene …”

Section: Resultssupporting

confidence: 72%

Influence of Structures of Polymer Backbones on Cooperative Photoreorientation Behavior of p-Cyanoazobenzene Side Chains

et al. 2001

View full text Add to dashboard Cite

Photoinduced orientational behavior of a polymethacrylate (CN6) and a polyester (p6a12) with p-cyanoazobenzene side chains was studied to reveal the structural effect of the liquid crystalline polymer backbones. Irradiation with linearly polarized UV light resulted in the reorientation of the azobenzene for both polymers toward the direction perpendicular to the electric vector of the incident light. The induced orientation can be slowly amplified by thermal Z-to-E isomerization and be facilitated by irradiation with visible light. For p6a12 with the long alkylene and carbonyl groups in main-chain cooperative orientation of main chains with p-cyanoazobenzene side chains was confirmed using FT-IR spectroscopy, contrary to the case of CN6. Furthermore, in-situ observation of changes in photoinduced birefringence by ellipsometry revealed that thermal treatment plays a significant role in levels of molecular orientation in polymer matrices.

show abstract

Section: Resultssupporting

confidence: 72%

Influence of Structures of Polymer Backbones on Cooperative Photoreorientation Behavior of p-Cyanoazobenzene Side Chains

et al. 2001

View full text Add to dashboard Cite

show abstract

“…10,11 This effect is important for the stability of induced anisotropy. 12 A high polarizability along the long molecular axis of the azobenzene fragments in the trans conformation determines birefringence effects for the light outside the absorption band. The refractive index for the light polarized along the long molecular axis n e is higher than the refractive indices in all the directions perpendicular to the long molecular axis n o .…”

Section: Introductionmentioning

confidence: 99%

“…Processes taking place during the irradiation of azobenzene compounds were extensively studied for different azobenzene containing media including viscous solutions of azobenzene molecules, 7 Langmuir-Blodgett films, 8 and polymers with azobenzene moieties that are chemically linked to a backbone ͑azopolymers͒. [1][2][3][4][9][10][11][12][13][14][15] The latter materials have the advantage of high stability of the induced anisotropy.…”

Section: Introductionmentioning

confidence: 99%

Light induced structures in liquid crystalline side-chain polymers with azobenzene functional groups

Yaroschuk

Sergan

Lindau

et al. 2001

The Journal of Chemical Physics

View full text Add to dashboard Cite

We applied ellipsometry to study the distribution of azobenzene fragments in the films of two types of comblike polymers with azobenzene moieties in the side chains before and after ultraviolet (UV) light irradiation. The polymer with an alkyl chain at the end of the azobenzene fragment forms structures with preferred homeotropic alignment of the fragments. Irradiation of this polymer with nonpolarized UV light at normal incidence induces a homeotropic alignment of azobenzene fragments. Oblique irradiation induces tilted structures. Polarized UV light irradiation at normal beam incidence induces biaxial structures with a fanlike distribution of azobenzene fragments and preferably out-of-plane alignment. The polymer with polar nitro group at the end of the azobenzene moiety shows preferential in-plane orientation. The degenerate in-plane alignment is retained for normal irradiation with nonpolarized UV light. Excitation with polarized light provides highly ordered in-plane alignment of the azobenzene fragments perpendicular to the UV light polarization. Re-orientation of the fragments under a second UV exposure with orthogonal polarization involves out-of-plane rotation of the fragments.

show abstract

“…Azobenzene-containing polymers are known to be among the most effective materials for PIA generation. [6][7][8][9][10][11][12][13][14] The photoinduced birefringence in some liquid crystalline (LC) azopolymers reaches 0.3. Most often, the induced order is stable, easily erasable, and rewritable.…”

Section: Introductionmentioning

confidence: 99%

“…

…”

mentioning

confidence: 99%

Molecular Structure of Azopolymers and Photoinduced 3D Orientational Order. 1. Azobenzene Polyesters

et al. 2004

Self Cite

View full text Add to dashboard Cite

The combination of transmission null ellipsometry (TNE) and attenuated total reflection (ATR) methods supported by absorption measurements is shown to be an effective tool to study spontaneous and photoinduced 3D order in azopolymers. We investigated a series of azobenzene containing side-chain polyesters differing by the length of the main-chain spacer (CH2) m (m = 2, 8, 9, 10, 12, 13, 14, 16) and the tail substitutes (NO2, OCH3, and OC4H9) in azochromophore. The 3D order was induced by monochromatic polarized light of several wavelengths strictly distinguished by absorption efficiency of azochromophores. The orientational order under irradiation and after irradiation is studied. A big variety of 3D orientations (biaxial, uniaxial, and isotropic) is realized. The uniaxial and isotropic configurations correspond to the initial state and the saturation state of irradiation, while biaxiality is an attribute of the transient orientations. It is shown that both initial and photoinduced 3D orders are strongly determined by molecular structure of azopolymers. If we exclude the case of ultrathin polymer films (d < 200 nm), the observed regularities can be summarized as follow. The homologues with NO2 tail group and m > 8 demonstrate strong preference for in-plane alignment, which is random in the initial state and uniaxially ordered in the saturated state of irradiation. The change of the tail substitute in the succession NO2 → OCH3 → OC4H9 leads to transition from the in-plane to the out-of-plane alignment of azochromophores (nonirradiated films), increase of the tendency of isotropic ordering (excitation within ππ* absorption band), and transition from the positive (prolate) to the negative (oblate) in-plane uniaxial order (excitation within nπ* absorption band). The observed regularities are explained by competition of photoorientation determined by symmetry of light and intrinsic self-organization determined by the structure of polymer molecules.

show abstract

<title>Mechanisms of light-induced orientation ordering of azobenzene-containing polymer molecules</title>

Cited by 3 publications

References 3 publications

Influence of Structures of Polymer Backbones on Cooperative Photoreorientation Behavior of p-Cyanoazobenzene Side Chains

Influence of Structures of Polymer Backbones on Cooperative Photoreorientation Behavior of p-Cyanoazobenzene Side Chains

Light induced structures in liquid crystalline side-chain polymers with azobenzene functional groups

Molecular Structure of Azopolymers and Photoinduced 3D Orientational Order. 1. Azobenzene Polyesters

Contact Info

Product

Resources

About