Photoresponsive side-chain liquid crystalline polymers with amide group-substituted azobenzene mesogens: effects of hydrogen bonding, flexible spacers, and terminal tails

Li, Xinjuan; Fang, Liangjing; Hou, Leigang; Zhu, Liya; Zhang, Ying; Zhang, Baolong; Zhang, Huiqi

doi:10.1039/c2sm25163a

Cited by 41 publications

(40 citation statements)

References 53 publications

(95 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…4-((4-Hydroxy)phenylazo)benzoic acid, 4-((4--hydroxyalkyloxy)phenylazo)benzoic acid (HAzoA-m (m = 2, 6, 10)), and 4-((4-(-acryloyloxyalkyloxy))phenylazo)benzoic acid 35 (AAzoA-m (m = 2, 6, 10)) were synthesized following our previous procedure (Scheme 1). [67][68][69] All the other reagents were commercially available and used without further purification unless otherwise stated.…”

Section: Methodsmentioning

confidence: 99%

Easily crosslinkable side-chain azobenzene polymers for fast and persistent fixation of surface relief gratings

et al. 2015

Self Cite

View full text Add to dashboard Cite

A series of side-chain azobenzene (azo) homo-and copolymers with easily crosslinkable Nhydroxysuccinimide carboxylate-substituted azo moieties and relatively low glass transition temperatures were synthesized for rapid and persistent fixation of surface relief gratings (SRGs). These azo polymers exhibited good thermal stability and their films proved easily crosslinkable within 4-15 min with 1,6-hexanediamine under mild conditions with the crosslinking rates of copolymer films being faster than 10 homopolymer films. Moreover, the formation speed and saturation modulation depth of the photoinduced SRGs increased both with a decrease in the flexible spacer length in azo homopolymers and with an increase in the azo contents in copolymers. Furthermore, considerably stabilized high quality SRGs were obtained after their post-fixation by crosslinking, as revealed by the negligible or rather small change of both the modulation depth of the crosslinked SRGs upon their exposure to high temperatures or organic 15 solvents and the transparency of the crosslinked polymer films.

show abstract

Section: Methodsmentioning

confidence: 99%

Easily crosslinkable side-chain azobenzene polymers for fast and persistent fixation of surface relief gratings

et al. 2015

Self Cite

View full text Add to dashboard Cite

show abstract

“…[8,11,[17][18][19][20]25] In this paper we investigated a series of three SCLCEs with azobenzene groups present in various concentrations, as both mesogens and cross-linkers, which had been synthesised to investigate their opto-mechanical responses. [9][10][11]22,23,25] The nematic-to-isotropic transition is partially first order in these systems and the specific temperature and temperature range over which the transition occurs depend upon the chemical composition of the elastomer, the concentration and chemical structures of the cross-linkers, and the mesogens present. The response observed in DSC is known to be broader and more diffuse for elastomeric systems.…”

Section: Introductionmentioning

confidence: 99%

“…[7] In their relaxed trans-state, the azobenzene molecules act as rigid rod-like molecules that contribute to the overall nematic order in the same manner as any other mesogen. Azobenzene-dyed materials have been shown to act as optically controlled actuators, [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25] which have been used to make micropumps and valves, [20] and show great potential in creating artificial muscles, [13][14][15][16] and are candidates for creating haptic displays. [9,17] The thermal properties of various azobenzenedyed thermotropic SCLCEs have been studied by wide-angle X-ray scattering (WAXS), differential scanning calorimetry (DSC), and polarising optical microscopy (POM).…”

Section: Introductionmentioning

confidence: 99%

“…[6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25] In recent years many SCLCEs have been synthesised with azobenzene structures as cross-linkers and/or mesogens, which has led to materials with coupled opto-mechanical properties. [6][7][8][9][10][11][12][13][22][23][24][25] These azobenzene compounds respond to light by undergoing a reversible trans→cis photo-isomerisation, where they become bent in shape, thereby lowering the nematic order and changing the mechanical response of the material. [7] In their relaxed trans-state, the azobenzene molecules act as rigid rod-like molecules that contribute to the overall nematic order in the same manner as any other mesogen.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Thermal characterisation of thermotropic nematic liquid-crystalline elastomers

et al. 2015

View full text Add to dashboard Cite

Nematic liquid-crystalline elastomers (LCEs) are weakly cross-linked polymeric networks that exhibit rubber elasticity and liquid-crystalline orientational order due to the presence of mesogenic groups. Three end-on sidechain nematic LCEs were investigated using real-time synchrotron wide-angle X-ray scattering (WAXS), differential scanning calorimetry (DSC), and thermogravimetry (TG) to correlate the thermal behaviour with structural and chemical differences among them. The elastomers differed in cross-linking density and mesogen composition. Thermally reversible glass transition temperature, T g , and nematic-to-isotropic transition temperature, T ni , were observed upon heating and cooling. By varying the heating rate, T g 0 and T ni 0 were determined at zero heating rate. The temperature dependence of the orientational order parameter was determined from the anisotropic azimuthal angular distribution of equatorial reflections seen during real-time WAXS. Results show that the choice of cross-linking unit, its shape, density, and structure of co-monomers, all influence the temperature range over which the thermal transitions take place. Including multi-ring aromatic groups as cross-linkers increased the effective stiffness of the cross-linking, resulting in a higher glass transition temperature. The nematic-to-isotropic transition temperature increased in the presence of multi-ring aromatic structures, as either cross-linkers or mesogens, particularly when the multi-ring structures were larger than the low-molar-mass mesogen common to all three samples.

show abstract

“…Cook et al have systematically researched the influence of flexible spacer length from 3 to 11 on the self‐organization of the poly[ω‐(4‐methoxyazobenzene‐4′‐oxy)alkyl methacrylate]s. Authors pointed out that the propyl and butyl members showed exclusively nematic behavior; the pentyl, hexyl, octyl, and decyl members formed a nematic and a smectic A phase, whereas the heptyl, nonyl, and undecyl homologues exhibited only a smectic A phase. Li et al have reported the synthesis of a series of new side‐chain liquid‐crystalline polymethacrylates with amide group‐substituted azo mesogens and different lengths of flexible spacers and terminal alkyl chains. In this context, hydrogen‐bonding interactions among the amide groups proved to play a decisive role in forming and stabilizing the smectic C phase.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and phase behaviors of side‐chain liquid‐crystalline polymers containing azobenzene mesogen with the different length alkyl tail

Chen

Ling

Zhang

2013

J. Polym. Sci. Part A: Polym. Chem.

View full text Add to dashboard Cite

A series of side‐chain liquid‐crystal polymers, poly[6‐[4‐(4′‐n‐alkyl benzoateazo)phenoxy]‐hexylmethacrylate]s (PMAzoCOORm, m = 1, 2, 3, 4, 5, 6, 8, 10, 14, and 18) have been prepared by two synthetic methods. The chemical structure of the monomers was confirmed by 1H NMR and mass spectrometry. The molecular characterizations of the polymers were performed with 1H NMR and gel permeation chromatograph. The phase behaviors of polymers were investigated by the combination of techniques including differential scanning calorimetry, polarized optical microscopy, and small‐angle X‐ray scattering. For m = 1, 2, 3, 4, 5, and 6, the polymers exhibited a monosmectic A phase in which the smectic layer period was almost identical to the side‐chain length. In addition, for m = 2, 3, 4, and 5, they presented the monosmectic C phase in low temperature; moreover, the tilt angle increased from 23.3 to 40.5°. For m = 8, 10, 14, and 18, the polymers showed a bilayer smectic A phase in which the layer spacing was larger than a fully extended side chain but less than two extended chains. On the other hand, for the clearing point, with the increasing of m, it first decreased, and then increased. All of these indicated that the length of alkyl tails played an important role in the phase behaviors of these polymers. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 2759–2768

show abstract

Photoresponsive side-chain liquid crystalline polymers with amide group-substituted azobenzene mesogens: effects of hydrogen bonding, flexible spacers, and terminal tails

Cited by 41 publications

References 53 publications

Easily crosslinkable side-chain azobenzene polymers for fast and persistent fixation of surface relief gratings

Easily crosslinkable side-chain azobenzene polymers for fast and persistent fixation of surface relief gratings

Thermal characterisation of thermotropic nematic liquid-crystalline elastomers

Synthesis and phase behaviors of side‐chain liquid‐crystalline polymers containing azobenzene mesogen with the different length alkyl tail

Contact Info

Product

Resources

About