Carbon nanotube-loaded liquid crystalline Diels− Alder networks (CNT-LCDANs) were prepared and utilized to investigate twisted fiber and spring actuators for light-driven rolling movement. The twisted fiber actuator was obtained by inserting twists into uniaxially stretched thin rods, while the spring actuator was built up by coiling the twisted fiber with either the same or opposite handedness, giving rise to a homochiral and heterochiral spring actuator, respectively. The programming of such hierarchically twisted geometries of liquid crystalline polymer networks was enabled by the easy processing and the concomitant stabilization of LC alignment of CNT-LCDAN due to the dynamic, thermally reversible DA-bonded cross-links. High-performance, environment-adaptable rolling motion powered by constant exposure to light was achieved with the twisted fiber and spring actuators. The appealing characteristics include ultrafast motion speed (reaching 22 mm s −1 ), multiterrain locomotion (including sand, water, and human hand), movement under near-infrared (NIR) or visible light or even natural sunlight (on dark gray or black paper), and squeezing through narrowed opening through in-motion reversible body compression and extension. The material of CNT-LCDAN and its twisted fiber and spring actuators hold promise in the development of next-generation soft robotics.

A porous liquid‐crystalline network (LCN), prepared by using a template method, was found to exhibit peculiar actuation functions. The creation of porosity makes the initially hydrophobic LCN behave like a hydrogel, capable of absorbing a large volume of water (up to ten times the sample size of LCN). When the amount of absorbed water is relatively small (about 100 % swelling ratio), the porous LCN displays anisotropic swelling in water and, in the same time, the retained uniaxial alignment of mesogens ensures a thermally induced shape change associated with a LC‐isotropic phase transition. Combining the characteristic actuation mechanisms of LCN (order–disorder transition of mesogens) and hydrogel (water absorption), such porous LCNs can be explored for versatile stimuli‐triggered shape transformations. Moreover, the porosity enables loading/removal/reloading of functional fillers such as ionic liquids, photothermal dyes and fluorophores, which imparts the porous LCN actuator with reconfigurable functions such as ionic conductivity, light‐driven locomotion, and emissive color.

Reactive oxygen species (ROS)-responsive prodrug nanoplatform (ROS-RPN) can controllably deliver drugs triggered by the overproduced ROS in tumor tissues. However, ROS-RPN may not work efficiently due to insufficient ROS concentrations,...

The amphiphilic block copolymer poly(ethylene oxide)-b-poly(N,N'-dihydroxypyromellitimide-hexamethylene diisocyanate) (PEO-b-PNH) with photocleavable N-O urethanes has been prepared to investigate the photodegradation of the hydrophobic main chain and therefore the disruption of copolymer micelles. Measurements of absorption and emission spectra, optical transmittance, DLS analysis, and TEM observations were applied. It was shown that PEO-b-PNH could self-assemble into flower compound micelles in water. The photodegradation of the hydrophobic polyurethane within the micellar core upon irradiation with 365 nm light could be conveniently controlled by changing the irradiation intensity; furthermore, complete micellar disruption could be achieved when 42% of N-O urethanes were photocleaved. By using DOX as the hydrophobic guest, the drug release profile showed a linear leakage of DOX out of the swelling polymer micelles in the initial stage and thereafter a much more quick exponential decay of DOX precipitation because of the micellar disruption upon further irradiation. The diffusion experiment of the leaked DOX into buffer solution (pH 7.4) showed that the DOX leakage could be prominently accelerated by a very short time of 365 nm irradiation, indicating that the N-O photocleavage can serve as a "turn-on" switch for the release of DOX in aqueous media.

Water-soluble copolymers of poly(acrylic acid-co-N-vinylcaprolactam) (PAN) and poly(acrylic acid-co-N-vinylcaprolactam-co-dimethyl acrylamide) (PAND) were synthesized and found to exhibit opposite, and pH-tunable, UCST (upper critical solution temperature) and LCST (lower critical solution...

The amphiphilic random copolymer of P(NVP-co-NHPSS) with photocleavable N-O sulfonate side groups has been prepared to investigate the light-triggered disruption of copolymer micelles. Methods of absorption and emission spectra, solution transmittance, dynamic light scattering (DLS), and transmission electron microscopy (TEM) were applied. It was found that P(NVP-co-NHPSS) could form polymeric nanoaggregates in aqueous solution. And the photocleavage of the N-O bond within copolymer micelles upon 365 nm UV light could be conveniently controlled by changing the irradiation intensity, leading to the disruption of copolymer micelles and the photocontrolled release of Nile red encapsulation. And by encapsulating NaLuF4:Gd/Yb/Tm UCNPs inside copolymer micelles, the response of the photocleavable N-O bond to the 980 nm laser was much weaker than the response to 365 nm light; however, the photocontrolled release of Nile red could still be effectively triggered by the NIR light of the 980 nm laser.

Fluorescent photolabile groups undergoing convenient synthesis and fast cleavage are being explored because of their increasing utility in both synthetic and biological chemistry. Herein, a model photosensitive poly(ethylene glycol)-lipid of NP-B-PEG with a 2-nitrobenzyl 2-pyridinylmethyl borate hydrophobic tail is synthesized. The (1) H-NMR and absorption spectra analysis of NP-B-PEG upon 365 nm irradiation in water supports a rapid photocleavage of nitrobenzyl borate with the concomitant hydrolysis of 2-pyridinylmethyl borate. It is also shown that the borate tail hydrolyzes slowly in water. Fortunately, when the polymer aqueous solution is loaded with the hydrophobic doxorubicin (DOX), the borate hydrolysis can be much retarded. The phototriggered experiment shows a two-stage DOX release: first, the slow leakage as a result of the photocleavage of 2-nitrobenzyl borate before the vesicle disintegration; second, the quick DOX precipitation from the disintegrated vesicles induced by the speeding up hydrolysis of 2-pyridinylmethyl borate.

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