Reversible Actuation of Polyelectrolyte Films: Expansion-Induced Mechanical Force Enables <i>cis–trans</i> Isomerization of Azobenzenes

Zhang, Yuanyuan; Ma, Ying; Sun, Junqi

doi:10.1021/la403019z

Cited by 26 publications

(33 citation statements)

References 53 publications

(69 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The authors hypothesized that this could be due to the slow polymer chain relaxation kinetics in the bulk material, resulting in a hysteresis between the cis ‐ trans isomerization of the azobenzene and the molecular and macroscopic motion of the polymer . Polyelectrolyte complexes between positively charged azobenzenes and polyanions have also been explored and exhibit similar properties and light responses …”

Section: Systems and Actuation Mechanismsmentioning

confidence: 99%

Light‐Responsive Shape‐Changing Polymers

Stoychev

Kirillova

Ionov

2019

Advanced Optical Materials

158

117

View full text Add to dashboard Cite

Shape‐changing polymers are an emerging class of smart stimuli‐responsive materials. Among the different stimuli that could be used for polymer actuation, light has several especially attractive features, including precise spatial and temporal remote control, easily tunable properties, and on‐demand pausing and resuming of the actuation. Consequently, light‐responsive polymers offer potential solutions to many pressing technological problems, especially where a noncontact form of stimulation and control is desired. In this review, state‐of‐the‐art advancements in the field of light‐responsive shape‐changing polymers are highlighted. The systems are classified according to the material type and the underlying light‐driven actuation/shape‐change mechanism. Finally, the most promising applications for light‐driven polymeric actuators are outlined, followed by challenges in the area and outlook on future promising directions.

show abstract

Section: Systems and Actuation Mechanismsmentioning

confidence: 99%

Light‐Responsive Shape‐Changing Polymers

Stoychev

Kirillova

Ionov

2019

Advanced Optical Materials

158

117

View full text Add to dashboard Cite

show abstract

“…Azobenzene chromophore is also a very interesting group of switchable molecules that respond to both near‐UV and visible light radiation . Such photoactive molecules are one of the most studied examples of materials exhibiting photoresponsive properties which can be integrated within 2D and 3D polymeric multilayer systems making use of the LbL assembly technique . Such structurally simple and readily accessed molecules, which display two phenyl rings linked by an azo (–N=N–) bond, experiment under UV light stimulation a uniquely simple, fast, efficient, clean, and reversible photochemical isomerization from the most energetically stable trans to the least stable cis geometric isomeric state, being accompanied by fast and significant changes in the physical properties such as polarity, viscosity, geometric shape, electronic structure, and absorbance (see Figure ) .…”

Section: Light‐responsive Lbl Polymeric Multilayer Assembliesmentioning

confidence: 99%

“…Such trans ‐to‐ cis isomerization states, which are highly dependent on the irradiation intensity, quantum yields and rate constants for the two processes, free volume, and on the functional groups attached to the chromophores, have been used to trigger several photoresponsive changes on several matrices . However, the metastable cis isomeric form is not stable and the molecule tend to isomerize back to the trans state once the UV light source is removed either thermally or by optical activation, due to the increase in the free volume provided by the expansion of the films . Overall, both trans ‐to‐ cis and cis ‐to‐ trans reactions proceed with high quantum yields and are completely reversible.…”

Section: Light‐responsive Lbl Polymeric Multilayer Assembliesmentioning

confidence: 99%

“…Overall, both trans ‐to‐ cis and cis ‐to‐ trans reactions proceed with high quantum yields and are completely reversible. The incorporation of azobenzene moieties into substrates modified with polymeric multilayer structures may lead to novel smart functional materials presenting different properties, namely polarity, molecular geometry, viscosity, solubility, degradability, and therefore adaptable self‐assembling behavior, well‐suited for a broad range of scientific studies covering several areas of research . In addition the permeability of such LbL assemblies can be tuned by controlling the amount of azodye embedded in the polymer backbone …”

Section: Light‐responsive Lbl Polymeric Multilayer Assembliesmentioning

confidence: 99%

See 1 more Smart Citation

Layer‐by‐Layer Assembly of Light‐Responsive Polymeric Multilayer Systems

Borges

Rodrigues

Reis

et al. 2014

Adv Funct Materials

113

View full text Add to dashboard Cite

wileyonlinelibrary.comcompositions, structures, and functions for several relevant applications. This goal has been achieved by engineering several nanostructured building blocks on surfaces through many processing methods. 'Bottom-up' methods, including Langmuir-Blodgett (LB), [1][2][3] self-assembled monolayers (SAMs), [4][5][6][7][8][9][10][11][12][13] and Layerby-Layer (LbL) assembly, [14][15][16][17][18][19] have been widely used to modify and effectively tailor the surface properties and simultaneously for assembling desired molecules with a high degree of control over organization and orientation. Therefore, these surface engineering strategies have been used to design and fabricate organized monolayer fi lms (in the case of SAM methodology) and multilayer assemblies (in the case of LB and LbL assembly approaches) with precisely layered structures, compositions, properties, and functions, and thus with enhanced performance at the molecular level. Furthermore, the bulk properties of nanostructured materials and the ability to precisely tailor the surface properties and fi nely tune the physicochemical properties and structures of engineered functional molecular assemblies have been recognized as having paramount importance for the scientifi c and engineering communities due to the broad range of possible applications in the biomedical, electronics, optics, catalysis, and energy research fi elds. [20][21][22] It is well known and commonly agreed that nature provides a great source of endless inspirations for designing highly sophisticated functional materials. Hence, scientists and engineers from different areas of chemistry, physics, engineering, biology, medicine, or biotechnology have been challenged to design and engineer environmentally sensitive biomimetic surfaces that would respond to specifi c external stimuli (e.g. temperature, pH, ionic strength, light, mechanical stress, electric, magnetic and ultrasonic fi elds, electric potential, specifi c biological moieties) in a very controllable and predictable manner, hence adjusting to our demands. Such smart surfaces have been developed by modifying surfaces with stimuliresponsive polymeric materials that ideally exhibit reversible switchable physicochemical properties (i.e., a polymer should be switched repeatedly rather than being designed for a single event), precisely tailored structures, compositions, and functions in response to changes in the surrounding environment. Layer-by-Layer (LbL) assembly is a simple and highly versatile method to modify surfaces and fabricate robust and highly-ordered nanostructured coatings over almost any type of substrate. Such versatility enables the incorporation of a plethora of building blocks, including materials exhibiting switchable properties, in a single device through a multitude of complementary intermolecular interactions. Switchable materials may undergo reversible physicochemical changes in response toa variety of external triggers. Although most of the works in the literature have been focusing on stimu...

show abstract

“…Approaches (ii) and (iv) are limited by the complexity of fabricating gradient polymer films and generating gradient stimulus fields. Meanwhile, although approach (iii) is likely the easiest to implement, and has therefore become very popular, the sensitivity of this type of actuator is inadequate: extreme operating voltages (>100 V) or temperature changes (even to hundreds of °C) are necessary and response times are lengthy (≈ 20 s) . Furthermore, dynamic fatigue of the bilayer structures remain a serious concern.…”

mentioning

confidence: 99%