Nature of the interaction between benzaldehyde links in polymer chains

Zyat'kov, I. P.; Могильный, В. В.

doi:10.1007/bf00659721

Cited by 3 publications

(5 citation statements)

References 5 publications

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“…The material B-15 is a representative of a novel class of polymers created at Belarusian State University, Belarus. They originate from photocross linkable materials developed as UV photoresists [15] and consist of macromolecules with photosensitive benzaldehyde groups attached to the main chain (figure 1(a)). Primarily, photoanisotropic properties of the new polymeric materials were investigated in the form of photoinduced birefringence, which was found to be 4 × 10 −4 [16,17].…”

Section: B-15 Alignment Materials For Plastic Substratesmentioning

confidence: 99%

Novel polymer as liquid crystal alignment material for plastic substrates

Mahilny

Станкевич

Muravsky

et al. 2009

J. Phys. D: Appl. Phys.

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Implementation of the roll-to-roll (R2R) process and printable organic electronics realizes the cost reduction potential of liquid crystal displays (LCDs) on plastic substrates. These innovative technologies put a strong limitation on the chemistry and temperature treatment of the LC alignment material applied at the solid–liquid interface inside the LCD. Alignment material is the last uniform layer deposited on each of the substrates before assembling and sealing of the whole display sandwich. Deposition from an aggressive solvent, vacuum deposition or a high baking temperature can not only destroy the complex composite structure of the electronics but can also affect the material properties of the substrate. We developed a new type of polymer alignment material, B-15, which can be deposited from a non-aggressive solvent (ethyl/butyl acetate) on top of the wide range of organic layers (including UV-curable materials and TAC films of plastic polarizer) without barrier layers for chemical protection. B-15 is suitable for the R2R process for only short-time treatment operations: 5 min baking at 90 °C is sufficient to remove the residual solvent and hard baking is not required. First, the rubbing process produces an alignment direction on the surface with the azimuthal anchoring energy over 10−4 J m−2. Next, non-polarized light exposure with a 254 nm Hg line induces photopolymerization, which also shifts the absorption peak far below the 300 nm wavelength. Thus B-15 is a highly photostable alignment material possessing null absorption in both the UV-A and the VIS ranges.

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Section: B-15 Alignment Materials For Plastic Substratesmentioning

confidence: 99%

Novel polymer as liquid crystal alignment material for plastic substrates

Mahilny

Станкевич

Muravsky

et al. 2009

J. Phys. D: Appl. Phys.

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“…We have used polymers containing benzaldehyde fragments as side groups with structures similar to those studied previously [10,11], exhibiting photosensitivity and demonstrating photoinduced birefringence [12]. This anisotropy is stable due to the formation of oriented cross-links between macromolecules under the action of polarized UV radiation [13].…”

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confidence: 99%

Controlled diffraction liquid-crystal structures with a photoalignment polymer

et al. 2008

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“…The benzaldehyde photosensitive fragments in the polymeric layers are liable to dimerization with efficiency increase as the benzaldehyde concentration grows. Dimers of the benzaldehyde units can be electron-excited both by direct light absorption and by nonradiative energy transfer from the isolated benzaldehydes due to lowering of the energy levels on dimerization [12]. The isolated and dimerized benzaldehyde groups could be regarded as the indicated molecular structures with the ratio apparently dependent on the benzaldehyde concentration.…”

Section: Resultsmentioning

confidence: 99%

“…where C 0 is the total initial concentration of the benzaldehyde units, C 0 M and C 0 D are their concentrations in isolated and dimerized states, respectively, V a = (4π/3)r 3 a , r a is the maximum distance between two benzaldehyde fragments required to form a dimer (r a ≈ 1 nm) [12], N A is the Avogadro constant. The results are given in table 2.…”

Section: Resultsmentioning

confidence: 99%

“…A positive birefringence decrease in this case could be considered as the result of worsening of the benzaldehyde dimer photoselection under excitation due to the radiationless energy transfer. Excitation of the dimers by energy transfer from the monomeric benzaldehyde units was discussed in [12]. One can estimate the ratio of the excited monomers delivering their energy to the dimers (P) by the formula [16]…”

Section: Resultsmentioning

confidence: 99%

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A new mechanism of stable optical birefringence recording under polarized UV radiation in photocrosslinking polymeric materials

Mahilny¹,

Trofimova²

2011

J. Opt.

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The photoinduced birefringence in glassy layers of the new photocrosslinking polymers containing benzaldehyde groups in the side chain is experimentally investigated. The kinetics of the birefringence recording is revealed to have an untypical shape compared to the known photosensitive materials of the same type. Under polarized UV exposure, the negative and positive birefringence are formed consecutively, the positive one being stable to the influence of liquids and heating (up to 120 °C). A new qualitative mechanism explaining the features revealed is proposed and verified by numerical simulation. According to the assumptions made, the positive birefringence is formed by anisotropic photocrosslinks which ensure its stability, which is of great importance for the practical application of the polymers under study, including liquid crystal photoalignment.

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Nature of the interaction between benzaldehyde links in polymer chains

Cited by 3 publications

References 5 publications

Novel polymer as liquid crystal alignment material for plastic substrates

Novel polymer as liquid crystal alignment material for plastic substrates

Controlled diffraction liquid-crystal structures with a photoalignment polymer

A new mechanism of stable optical birefringence recording under polarized UV radiation in photocrosslinking polymeric materials

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