A Continuous Flow Synthesis of Micrometer‐Sized Actuators from Liquid Crystalline Elastomers

Ohm, C. C.; Serra, Christophe A.; Zentel, Rudolf

doi:10.1002/adma.200901522

Cited by 167 publications

(168 citation statements)

References 17 publications

Supporting

Mentioning

159

Contrasting

Unclassified

Order By: Relevance

“…The LCE shell composed the three-core mesogen shown in Fig. 1b, which has previously been processed in microfluidic and templating devices 17,18,30 , but not for making core-shell particles. Attached to the rigid mesogenic unit are three flexible side chains, one of which comprises a polymerizable acrylate group.…”

Section: Resultsmentioning

confidence: 99%

“…They could thus be manufactured at moderate temperatures in a surrounding aqueous medium [31][32][33][34] . With an isotropization temperature of 80 1C, the reactive monomer mixture used in this study needs to be processed at elevated temperatures and requires a customized heat-resistant microfluidic device 30 . Thus, temperature-tolerant silicone oil was chosen as the outer continuous phase.…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

One-piece micropumps from liquid crystalline core-shell particles

et al. 2012

Self Cite

View full text Add to dashboard Cite

Responsive polymers are low-cost, light weight and flexible, and thus an attractive class of materials for the integration into micromechanical and lab-on-chip systems. Triggered by external stimuli, liquid crystalline elastomers are able to perform mechanical motion and can be utilized as microactuators. Here we present the fabrication of one-piece micropumps from liquid crystalline core-shell elastomer particles via a microfluidic double-emulsion process, the continuous nature of which enables a low-cost and rapid production. The liquid crystalline elastomer shell contains a liquid core, which is reversibly pumped into and out of the particle by actuation of the liquid crystalline shell in a jellyfish-like motion. The liquid crystalline elastomer shells have the potential to be integrated into a microfluidic system as micropumps that do not require additional components, except passive channel connectors and a trigger for actuation. This renders elaborate and high-cost micromachining techniques, which are otherwise required for obtaining microstructures with pump function, unnecessary.

show abstract

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

One-piece micropumps from liquid crystalline core-shell particles

et al. 2012

Self Cite

View full text Add to dashboard Cite

show abstract

“…17(B)). This design was important as it allowed further development by using capillaries instead of the discrete phase needle [157,160,[194][195]. Theoretically, monodisperse particles with few µmeters in diameter should be possible to achieve via this type of devices since down to 2 µm internal diameter capillaries are commercially available.…”

Section: Types Of Microfluidic Devicesmentioning

confidence: 99%

“…It is the elaborate chip design that allowed researchers not only to miniaturize microchannel emulsification reactors and prepare narrowly monodisperse spherical beads but also to achieve unprecedented control over structure and shape of particles. This unique capability of control resulted in the realization of perfectly controlled multiple emulsions [136][137][138][139][140][141][142][143][144][145], Janus particles [146][147][148][149][150][151][152][153][154][155][156], regular nonspherical shapes [157][158][159][160][161][162][163][164][165][166] and even gas bubbles [167][168][169][170][171], almost all of which were impossible to achieve before.…”

Section: Microfluidics: the Ultimate Controlmentioning

confidence: 99%

Porous polymer particles—A comprehensive guide to synthesis, characterization, functionalization and applications

Gökmen

Prez

2012

Progress in Polymer Science

440

309

View full text Add to dashboard Cite

“…In stimuli-responsive polymers capable of a free-standing shape-changing effect, this alignment is achieved during synthesis or processing by either application of external stress or the utilization of templates and fixed by covalent cross-links (5)(6)(7)(8)(9)(10)(11)(12). Once synthesis is completed, the geometry of the shape change cannot be changed anymore (13)(14)(15) and the actuation temperature is fixed; this relies on thermal transitions with a defined temperature.…”

mentioning

confidence: 99%

Temperature-memory polymer actuators

Behl

Kratz

Noechel

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

272

240

View full text Add to dashboard Cite

Reading out the temperature-memory of polymers, which is their ability to remember the temperature where they were deformed recently, is thus far unavoidably linked to erasing this memory effect. Here temperature-memory polymer actuators (TMPAs) based on cross-linked copolymer networks exhibiting a broad melting temperature range (ΔT m ) are presented, which are capable of a long-term temperature-memory enabling more than 250 cyclic thermally controlled actuations with almost constant performance. The characteristic actuation temperatures T act s of TMPAs can be adjusted by a purely physical process, guiding a directed crystallization in a temperature range of up to 40°C by variation of the parameter T sep in a nearly linear correlation. The temperature T sep divides ΔT m into an upper T m range (T > T sep ) forming a reshapeable actuation geometry that determines the skeleton and a lower T m range (T < T sep ) that enables the temperature-controlled bidirectional actuation by crystallization-induced elongation and melting-induced contraction. The macroscopic bidirectional shape changes in TMPAs could be correlated with changes in the nanostructure of the crystallizable domains as a result of in situ Xray investigations. Potential applications of TMPAs include heat engines with adjustable rotation rate and active building facades with self-regulating sun protectors.reversible shape-memory polymer | active movement T he alignment and coupling of thermally controlled volume changes on the nanoscale has emerged as most important working principle to translate shape changes from the nanolevel to the macrolevel in polymers (1-4). In stimuli-responsive polymers capable of a free-standing shape-changing effect, this alignment is achieved during synthesis or processing by either application of external stress or the utilization of templates and fixed by covalent cross-links (5-12). Once synthesis is completed, the geometry of the shape change cannot be changed anymore (13-15) and the actuation temperature is fixed; this relies on thermal transitions with a defined temperature. Here we explored whether it is possible to implement a thermally controlled bidirectional actuation into free-standing polymers by purely physical manipulation enabling to adjust (repeatedly) the actuation temperature and (shape changing) geometry.Although programmable shape changes have been realized in shape-memory polymers (SMPs), this effect is generally a onetime, one-way effect in free-standing SMPs (16-18). In SMPs the switching domains, which can solidify by crystallization or vitrification, provide two functions: they determine the geometry of the shape change and cause the entropy elastic recovery. A reversible movement could be observed when polymers with crystallizable segments are held under an externally applied constant stress (3,8). Recently temperature-memory polymers (TMPs) enabled the programming of the switching temperature (19,20). Also this temperature-memory effect (TME) is limited to a onetime, one-way effect. The aim of th...

show abstract

A Continuous Flow Synthesis of Micrometer‐Sized Actuators from Liquid Crystalline Elastomers

Cited by 167 publications

References 17 publications

One-piece micropumps from liquid crystalline core-shell particles

One-piece micropumps from liquid crystalline core-shell particles

Porous polymer particles—A comprehensive guide to synthesis, characterization, functionalization and applications

Temperature-memory polymer actuators

Contact Info

Product

Resources

About