Synthesis of a Photoresponsive Liquid‐Crystalline Polymer Containing Azobenzene

Li, Chensha; Lo, Chi-Wei; Zhu, Difeng; Li, Chenhui; Liu, Ye; Jiang, Hongrui

doi:10.1002/marc.200900421

Cited by 54 publications

(32 citation statements)

References 39 publications

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“…One strategy for sensitizing LCEs to an external energy source is to modify them with stimuli-responsive organic functional groups, either by covalently attaching these to the polymeric chains [23,24] or by physically adsorbing them into swelling LCEs [25]. Several photo-responsive LCEs have been developed by introducing photochromic groups into the LCEs [26,27]. The majority of these photochromic molecules are azobenzene derivatives, although stilbene derivatives are also studied.…”

Section: Open Accessmentioning

confidence: 99%

Nanoparticle-Liquid Crystalline Elastomer Composites

Marshall

Terentjev

2012

Polymers

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Liquid crystalline elastomers (LCEs) exhibit a number of remarkable physical effects, including a uniquely high-stroke reversible mechanical actuation triggered by external stimuli. Fundamentally, all such stimuli affect the degree of liquid crystalline order in the polymer chains cross-linked into an elastic network. Heat and the resulting thermal actuation act by promoting entropic disorder, as does the addition of solvents. Photo-isomerization is another mechanism of actuation, reducing the orientational order by diminishing the fraction of active rod-like mesogenic units, mostly studied for azobenzene derivatives incorporated into the LCE composition. Embedding nanoparticles provides a new, promising strategy to add functionality to LCEs and ultimately enhance their performance as sensors and actuators. The motivation for the combination of nanoparticles with LCEs is to provide better-controlled actuation stimuli, such as electric and magnetic fields, and broad-spectrum light, by selecting and configuring the appropriate nanoparticles in the LCE matrix. Here we give an overview of recent advances in this area with a focus on preparation, physical properties and actuation performance of the resultant nanocomposites.

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Section: Open Accessmentioning

confidence: 99%

Nanoparticle-Liquid Crystalline Elastomer Composites

Marshall

Terentjev

2012

Polymers

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“…CuBr and CuCl are purified according to Xue et al (2002), 4-nitroaniline (98%) was bought from the Alfa Aesar (Tianji). Monomer 6-(4-(phenylazo) benzoate) hexyl methacrylate) (AzoMA) was synthesized according to Yu X. et al (2006), Yu H. et al (2008), and Li et al (2009). All solvents and other regents were purchased from the Sinopharm Chemical Reagent Co., Ltd., and were used as received.…”

Section: Methodsmentioning

confidence: 99%

Surface pattern based on an azobenzene-containing copolymer thin film and its light-driven morphology modulation

Zhang

Wang

2013

J. Zhejiang Univ. Sci. A

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Abstract:A type of azobenzene-containing block copolymer polymethyl methacrylate-b-poly (n-butylmethacrylate-co-6-(4-(phenylazo) benzoate) hexyl methacrylate) (PMMA-b-(PnBMA-co-PAzoMA)) was synthesized by the atom transfer radical polymerization (ATRP). Macroinitiator polymethyl methacrylate (PMMA) was prepared by ATRP and used to initiate the copolymerization of monomer n-butyl methacrylate (nBMA) and azobenzene-based methacrylate monomer (AzoMA). Herein, three block copolymers with different molecular weights and block volume fractions were obtained and spin-coated on a silicon substrate or quartz plate before annealing at 180 °C for 14 h. The surface morphologies in these annealed copolymer films were observed by atomic force microscopy (AFM). Bicontinuous stripe or island patterns with different sizes were formed dependent on the film thickness. These ordered patterns are considered to be formed arising from the dewetting process of the surface layer in the copolymer film. Photoisomerization of azobenzene units in the copolymer films changed the dewetting behaviors of the surface layer of the thin film. Therefore, some copolymer annealed films showed a reversible morphology conversion between bicontinuous stripe and island structure when exposed to UV light and upon being stored in the dark. It was found that the composition of the block copolymer had obvious influences on the photoinduced morphology conversion behaviors in these copolymer thin films. When the volumes of PnBMA and PAzoMA phases in the block copolymer were large enough, the surface morphology could be modulated by UV light irradiation and storage in the dark. This work proposes a new possibility for photoinduced control and design of the dewetting processes of thin films using a linear block copolymer.

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“…By using this approach, several types of LCE have been synthesized. For instance, acrylate functionalized monomer mixed together with radical initiator (thermal/UV), using diacrylate as crosslinker, is employed to yield LCE [46,47,48,49]. Main chain LCEs, which utilize this synthetic approach, have been synthesized by polymerizing LC monomer (with vinyl and mercapto group) and multifunctional crosslinker (with two vinyl and mercapto groups) using a radical photo-initiator [50,51,52].…”

Section: Liquid-crystalline Elastomers (Lces)mentioning

confidence: 99%

“…Synthetic route for the synthesis of photosensitive LCEs [49]. The polymerizations were initiated thermally by mixing monomer and crosslinker together with the initiator.…”

Section: Liquid-crystalline Elastomers (Lces)mentioning

confidence: 99%

Photo-Responsive Shape-Memory and Shape-Changing Liquid-Crystal Polymer Networks

2013

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“Surrounding matters” is a phrase that has become more significant in recent times when discussing polymeric materials. Although regular polymers do respond to external stimuli like softening of material at higher temperatures, that response is gradual and linear in nature. Smart polymers (SPs) or stimuli-responsive polymers (SRPs) behave differently to those external stimuli, as their behavior is more rapid and nonlinear in nature and even a small magnitude of external stimulus can cause noticeable changes in their shape, size, color or conductivity. Of these SRPs, two types of SPs with the ability to actively change can be differentiated: shape-memory polymers and shape-changing polymers. The uniqueness of these materials lies not only in the fast macroscopic changes occurring in their structure but also in that some of these shape changes are reversible. This paper presents a brief review of current progress in the area of light activated shape-memory polymers and shape-changing polymers and their possible field of applications.

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Synthesis of a Photoresponsive Liquid‐Crystalline Polymer Containing Azobenzene

Cited by 54 publications

References 39 publications

Nanoparticle-Liquid Crystalline Elastomer Composites

Nanoparticle-Liquid Crystalline Elastomer Composites

Surface pattern based on an azobenzene-containing copolymer thin film and its light-driven morphology modulation

Photo-Responsive Shape-Memory and Shape-Changing Liquid-Crystal Polymer Networks

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