Enhanced, Perpendicular Liquid‐Crystal Alignment on Rubbed Films of a Coumarin‐Containing Polystyrene

Kang, Hyo; Kwon, Ki‐Sun; Kang, Daeseung; Lee, Jong-Chan

doi:10.1002/macp.200700270

Cited by 27 publications

(6 citation statements)

References 58 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In addition, the presence of bulky aromatic rings on the HEPs backbone structure would give rise to the higher thermal stability of HEPs. 19 Xu et al 20 and Kang et al 21 also reported that the bulky aromatic group could significantly improve the thermal stability of the polymer. In comparison to the weight loss of the polyester composite filled with HEPs, the weight loss of the neat polyester due to thermal decomposition is higher.…”

Section: Thermal Characterizationmentioning

confidence: 99%

Mechanical, thermal and water absorption behavior of hollow epoxy particle–filled polyester composites

Low

Bakar

2013

Journal of Composite Materials

View full text Add to dashboard Cite

A water-based emulsion method was used in this study to produce hollow epoxy particles. The hollow epoxy particles were then chemically treated with hydrochloric acid solution to eliminate the excessive calcium carbonate on the surface of the hollow epoxy particles. The hydrochloric acid–treated hollow epoxy particles were added to the polyester matrix at different loading values (0–9 wt%). The addition of 5 wt% hollow epoxy particles to the polyester matrix optimized the mechanical properties (i.e., tensile strength, tensile modulus and flexural strength) of hollow epoxy particle–filled polyester composites. The interlocking of the polyester matrix into the pore regions of the hollow epoxy particles strengthened the polyester composites. The addition of hollow epoxy particles to the polyester matrix increased the thermal stability, storage modulus and the glass transition temperature of the polyester composite. The water absorption and diffusion coefficient of the polyester composite were also increased with the increase of the hollow epoxy particle loading.

show abstract

Section: Thermal Characterizationmentioning

confidence: 99%

Mechanical, thermal and water absorption behavior of hollow epoxy particle–filled polyester composites

Low

Bakar

2013

Journal of Composite Materials

View full text Add to dashboard Cite

show abstract

“…14,21,24,25,31,32,[48][49][50][51][52][53][54][55][56][57][58][59][60][61] Second is photodimerization caused by cinnamate, coumarin, and chalcone. [15][16][17]27,[62][63][64][65][66][67][68][69][70][71][72][73][74][75][76][77][78][79][80][81] Third is polyimide undergoing photodecomposition. [82][83][84] Moreover, polyimide-based photoalignment layers can be designed with a photoreactive group as a side chain or a backbone structure, and polyimide itself can induce…”

Section: Introductionmentioning

confidence: 99%

Photo‐isomerization, photodimerization, and photodegradation polyimides for a liquid crystal alignment layer

Sugiyama

Sato

Nagai

2022

Polymers for Advanced Techs

View full text Add to dashboard Cite

We review the important features of LC orientation for the alignment layer, namely, production method, alignment mechanisms, and required properties. Photoalignment, which could eliminate the disadvantages of the rubbing method is explored. Applicable materials and techniques for photoalignment are also examined. Many materials for photoalignment layers have been proposed, but polyimide‐based materials are commonly used because of their transparency and insulation properties, which are needed for optical electronic devices. Furthermore, photoisomerization, photodimerization, and photodecomposition as photoalignment methods are reviewed, and specific photoreactive groups and alignment mechanisms are used to induce LC alignment. In summary, polyimides cause photodecomposition and have the following disadvantages; (1) requirement of relatively short‐wavelength ultraviolet (UV) irradiation, (2) difficulty in reorienting polymer chains owing to their rigid polymer matrix, and (3) low‐photo reactivities. The solutions for each disadvantage are already proposed, but the required properties should be determined during material design. Polyimide‐based materials introduced with the azobenzene and cinnamate groups are proposed and found to have the ability of fulfilling the required properties. The mechanism of polyimide photodecomposition is not fully understood. It likely has the advantage in terms of LC alignment stability because of the absence of E/Z isomerization. Therefore, the alignment mechanism and availabilities should be further explored.

show abstract

“…Because photoalignment technique is a highly producible process due to clean process, adaptiveness to large glass, and unrestrictedness to surface morphology. A number of photoreactive polymers, which are photoisomeric [18][19][20], photodimeric [21][22][23][24][25][26], and photodegradable [27][28][29] polymers, have been studied for LC alignment in past decades. Especially, photoreactive polymer containing coumarin group has been considered as a candidate in advanced LC alignment layer due to good thermal property and uniform LC aligning ability [24][25][26].…”

Section: Introductionmentioning

confidence: 99%

Liquid Crystal Alignment Behaviors of Polystyrene Derivatives Containing Coumarin Moieties

Kang

Hong

Kang

2014

Molecular Crystals and Liquid Crystals

Self Cite

View full text Add to dashboard Cite

We synthesized a series of polystyrene derivatives containing coumarin side groups, poly (7-(4-vinylbenzyloxy)coumarin) (P7COU#) and poly (7-(4-vinylbenzyloxy)4-phenylcoumarin) (P7COU4P#), where # is the molar content of 7-hydroxycoumarin and 7-hydroxy-4-phenyl coumarin, respectively, using polymer analogous reaction, in order to study the effect of the 7-hydroxycoumarin and 7-hydroxy-4-phenyl coumarin side groups on the liquid crystal (LC) alignment properties. The LC alignment behavior of these two series was investigated by photoalignment or rubbing alignment. The LC cells made from photoirradiated P7COU# and P7COU4P# films showed homogeneous planar LC alignment. We found that LC aligning ability of the LC cells made from rubbed P7COU# and P7COU4P# films were affected by the structure and molar content of coumarin side groups. For example, anchoring energy of the LC cell fabricated with rubbed P7COU82 (7 × 10 −5 J/m 2 ) and P7COU4P81 (7 × 10 −7 J/m 2 ) film was increased drastically and slightly compared to polystyrene (10 −7 −10 −8 J/m 2 ), respectively. Particularly, anchoring energy of the LC cell made from rubbed P7COU# having more than 51 mol % of the 7-hydroxycoumarin as a side groups is comparable to that of the conventional polyimide in the LCD industry.

show abstract

Enhanced, Perpendicular Liquid‐Crystal Alignment on Rubbed Films of a Coumarin‐Containing Polystyrene

Cited by 27 publications

References 58 publications

Mechanical, thermal and water absorption behavior of hollow epoxy particle–filled polyester composites

Mechanical, thermal and water absorption behavior of hollow epoxy particle–filled polyester composites

Photo‐isomerization, photodimerization, and photodegradation polyimides for a liquid crystal alignment layer

Liquid Crystal Alignment Behaviors of Polystyrene Derivatives Containing Coumarin Moieties

Contact Info

Product

Resources

About