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stimuli responsive materials

Hideto Terada, Hiroaki Imai, Yuya Oaki
Visualization and quantitative detection of external stimuli are significant challenges in materials science. Quantitative detection of friction force, a mechanical stress, is not easily achieved using conventional stimuli-responsive materials. Here, the quantitative detection of friction force is reported, such as the strength and accumulated ammount, from the visible color of organic layered composites consisting of polydiacetylene (PDA) and organic amines without an excitation light source. The composites of the layered diacetylene monomer crystal and interlayer organic amine are synthesized through self-organization from the precursor solution...
May 18, 2018: Advanced Materials
Shuang Bai, Meili Hou, Xiaoxiao Shi, Jiucun Chen, Xiaoqian Ma, Yong-E Gao, Yajun Wang, Peng Xue, Yuejun Kang, Zhigang Xu
As one of the medical polymers approved by US Food and Drug Administration (FDA), poly(ethylene glycol) has low toxicity, high stability, good biocompatibility, unique physical and chemical properties. Cyclodextrin is an ideal candidate as a drug carrier due to its special structures and characteristics. These two materials were successfully assembled through chemosynthesis in combination with the hydrophilic poly(ethylene glycol) methyl ether methacrylate (OEGMA) chain and hydrophobic polymeric camptothecin (CPT) chain by atom transfer radical polymerization (ATRP)...
August 1, 2018: Carbohydrate Polymers
Nathan A Carter, Tijana Z Grove
Generation of electric potential upon external stimulus has attracted much attention for the development of highly functional sensors and devices. Herein, we report large-displacement, fast actuation in the self-assembled engineered repeat protein Consensus Tetratricopeptide Repeat protein (CTPR18) materials. The ionic nature of the CTPR18 protein coupled to the long-range alignment upon self-assembly results in the measured conductivity of 7.1 × 10-2 S cm-1, one of the highest reported for protein materials...
May 17, 2018: Journal of the American Chemical Society
Giuseppe Cavallaro, Giuseppe Lazzara, Lorenzo Lisuzzo, Stefana Milioto, Filippo Parisi
Halloysite nanotubes were functionalized with stimuli-responsive macromolecules to generate smart nanohybrids. Poly(N-isopropylacrylamide)-co-methacrylic acid (PNIPAAM-co-MA) was selectively adsorbed into halloysite lumen by exploiting electrostatic interactions. Amine-terminated PNIPAAM polymer was also investigated that selectively interacts with the outer surface of the nanotubes. The adsorption site has a profound effect on the thermodynamic behavior and therefore temperature responsive features of the hybrid material...
May 17, 2018: Nanotechnology
Alexey S Berezin, Denis G Samsonenko, Valery K Brel, Alexander V Artem'ev
Unprecedented organic-inorganic hybrid complexes, [Mn(L)3]MnHal4, containing both four- and hexacoordinated Mn2+ ions were synthesized by reacting MnCl2 or MnBr2 with bis(phosphine oxide) ligands (L) such as dppmO2, dppeO2, and 2,3-bis(diphenylphosphinyl)-1,3-butadiene (dppbO2). In the [Mn(L)3]2+ cation of the complexes, the Mn2+ ion features a [MnO6] octahedral coordination environment (Oh), and the [MnHal4]2- anion adopts a tetrahedral geometry (Td). These "two-in-one" complexes exhibit strong long-lived luminescence (τav = 12-15 ms at 300 K) having interesting thermochromic behavior attributed to the thermal equilibrium between two emission bands...
May 17, 2018: Dalton Transactions: An International Journal of Inorganic Chemistry
Alejandra Marful, Antonio M Díez-Álamo, Susana Plaza-Navas, Angel Fernandez
Research on familiar faces has recurrently been conducted in different domains, such as, psycholinguistics, memory, attention, face processing, aging studies, etc. In general, photographs of celebrities, their proper names, or their occupations have been the materials mainly employed in those types of studies. These stimuli are, however, very constrained by the geographic and sociocultural contexts in which the studies are conducted, and, in spite of their relevance for psychological research, there are no normative studies for celebrities in Spain...
2018: PloS One
Na Sun, Panpan Sun, Aoli Wu, Xuanxuan Qiao, Fei Lu, Liqiang Zheng
Stimuli-responsive or "smart" soft materials have raised considerable attention due to their ability to spontaneously respond to external environmental variations and have a great potential for wide applications. Herein, a thermo/redox responsive hydrogel is facilely constructed based on a dual crosslinked matrix: the primary chemical crosslinked copolymer is composed of thermo-responsive poly(N-isopropylacrylamide) (PNIPAM) and poly(ionic liquid), and the secondary physical crosslinking component is generated by the ionic coordination between iron ions and carboxyl groups in the poly(ionic liquid)...
May 15, 2018: Soft Matter
Ren-Tsung Wu, Xiaodong Chi, Takehiro Hirao, Vincent M Lynch, Jonathan L Sessler
A new carboxylic acid-functionalized "Texas-sized" molecular box TxSB-CO2H has been prepared by combining two separate build-ing blocks via an iodide-catalyzed macrocyclization reaction. A single crystal X-ray diffraction analysis revealed a paired "clip-like" dimer in the solid state. Concentration-dependent behavior is seen for samples of TxSB-CO2H as prepared, as inferred from 1H NMR spectroscopic studies carried out in DMSO-d6. However, in the presence of excess acid (1% by weight of deuterated trifluo-racetic acid; TFA-d1), little evidence of aggregation is seen in DMSO-d6 except at the highest accessible concentrations...
May 14, 2018: Journal of the American Chemical Society
Shumin Liang, Xiaxin Qiu, Jun Yuan, Wei Huang, Xuemin Du, Lidong Zhang
Soft robots, sensors and energy harvesters require materials that are capable of converting external stimuli to visible deformations, and especially shape-programmable deformations are desired. Herein, we develop a polymer film that can reversibly respond to humidity, heating and acetone vapors with generation of shape-programmable large deformations. Polyvinylidene fluoride (PVDF) film, capable of providing acetone responsiveness, is designed with microchannel patterns on one side by using templates, and the microchannels-patterned side is then treated with hygroscopic 3-aminopropyltriethoxysilane (APTES) to give humidity/heating-responsive elements...
May 14, 2018: ACS Applied Materials & Interfaces
Young-Ki Kim, Xiaoguang Wang, Pranati Mondkar, Emre Bukusoglu, Nicholas L Abbott
Liquid crystals (LCs) are anisotropic fluids that combine the long-range order of crystals with the mobility of liquids1,2 . This combination of properties has been widely used to create reconfigurable materials that optically report information about their environment, such as changes in electric fields (smart-phone displays) 3 , temperature (thermometers) 4 or mechanical shear 5 , and the arrival of chemical and biological stimuli (sensors)6,7 . An unmet need exists, however, for responsive materials that not only report their environment but also transform it through self-regulated chemical interactions...
May 9, 2018: Nature
Milena Nadgorny, Amir Ameli
Three-dimensional printing (3DP) has attracted a considerable amount of attention during the past years, being globally recognized as one of the most promising and revolutionary manufacturing technologies. Although the field is rapidly evolving with significant technological advancements, materials research remains a spotlight of interest, essential for the future developments of 3DP. Smart polymers and nanocomposites, which respond to external stimuli by changing their properties and structure, represent an important group of materials that hold a great promise for the fabrication of sensors, actuators, robots, electronics, and medical devices...
May 9, 2018: ACS Applied Materials & Interfaces
Heming Zhang, Xuhai Chen, Shengdong Chen, Yansong Li, Changming Chen, Quanshan Long, Jiajin Yuan
Facial and vocal expressions are essential modalities mediating the perception of emotion and social communication. Nonetheless, currently little is known about how emotion perception and its neural substrates differ across facial expression and vocal prosody. To clarify this issue, functional MRI scans were acquired in Study 1, in which participants were asked to discriminate the valence of emotional expression (angry, happy or neutral) from facial, vocal, or bimodal stimuli. In Study 2, we used an affective priming task (unimodal materials as primers and bimodal materials as target) and participants were asked to rate the intensity, valence, and arousal of the targets...
May 9, 2018: Neuroscience Bulletin
Rico Keidel, Ali Ghavami, Dersy M Lugo, Gudrun Lotze, Otto Virtanen, Peter Beumers, Jan Skov Pedersen, Andre Bardow, Roland G Winkler, Walter Richtering
Adaptive hydrogels, often termed smart materials, are macromolecules whose structure adjusts to external stimuli. Responsive micro- and nanogels are particularly interesting because the small length scale enables very fast response times. Chemical cross-links provide topological constraints and define the three-dimensional structure of the microgels, whereas their porous structure permits fast mass transfer, enabling very rapid structural adaption of the microgel to the environment. The change of microgel structure involves a unique transition from a flexible, swollen finite-size macromolecular network, characterized by a fuzzy surface, to a colloidal particle with homogeneous density and a sharp surface...
April 2018: Science Advances
H A Schwartz, U Ruschewitz, L Heinke
Smart, molecularly structured materials with remote-controllable properties and functionalities attract particular attention and may enable advanced applications. In this respect, the embedment of stimuli-responsive molecules, such as azobenzenes, spiropyrans or diarylethenes, in metal-organic frameworks (MOFs) is a very fascinating approach, resulting in easily accessible photoswitchable, nanoporous hybrid materials. It is an attractive alternative to the incorporation of the smart moieties in the MOF scaffold, which usually demands complex synthetic efforts...
May 8, 2018: Photochemical & Photobiological Sciences
Hai-Peng Chen, Ping-Ping Shi, Zhong-Xia Wang, Ji-Xing Gao, Wan-Ying Zhang, Cheng Chen, Yuan-Yuan Tang, Da-Wei Fu
Molecular bistable dielectric switches represent a class of highly desirable intelligent materials due to their sensitive switchable responses, simple and environmentally friendly processing, light weights, and mechanical flexibility. However, most of these switches can only work at a very low temperature, extremely limiting their potential applications. Herein, three layered organic-inorganic hybrid perovskite-type compounds of the general formula A2BX4, [NH3(CH2)2Cl]2[CdCl3Br] (1), [NH3(CH2)2Cl]2[CdCl4] (2) and [NH3(CH2)2Cl]2[CdBr4] (3), which display sensitive dielectric switching reversibility and remarkable switching anti-fatigue, have been successfully designed...
May 8, 2018: Dalton Transactions: An International Journal of Inorganic Chemistry
Mercedes Santos, Sofia Serrano-Ducar, Juan Gonzalez-Valdivieso, Reinaldo Vallejo, Alessandra Girotti, Purificacion Cuadrado, Francisco Javier Arias
Protein-based polymers are some of the most promising candidates for a new generation of innovative biomaterials as recent advances in genetic-engineering and biotechnological techniques mean that protein-based biomaterials can be designed and constructed with a high degree of complexity and accuracy. Moreover, their sequences, which are derived from structural protein-based modules, can easily be modified to include bioactive motifs that improve their functions and material-host interactions, thereby satisfying fundamental biological requirements...
May 7, 2018: Current Medicinal Chemistry
Tim R Dargaville, Jong-Ryul Park, Richard Hoogenboom
The synthesis of poly(2-oxazoline)s has been known since the 1960s. In the last two decades, they have risen in popularity thanks to improvements in their synthesis and the realization of their potential in the biomedical field due to their "stealth" properties, stimuli responsiveness, and tailorable properties. Even though the bulk of the research to date has been on linear forms of the polymer, they are also of interest for creating network structures due to the relatively easy introduction of reactive functional groups during synthesis that can be cross-linked under a variety of conditions...
May 7, 2018: Macromolecular Bioscience
Kai Jiang, Yuhui Wang, Congzhong Cai, Hengwei Lin
Stimuli-responsive optical materials have received tremendous interest in the last several decades due to their numerous promising applications. Here, fluorescence emissive polymer carbon dots (F-CDs), prepared with a simple heating treatment from ethylenediamine and phosphoric acid, are found to produce unexpected ultralong room-temperature phosphorescence (URTP), which lasts for about 10 s with a lifetime of 1.39 s. This is the first example to achieve the conversion of a fluorescence material to URTP by means of an external heating stimulus...
May 7, 2018: Advanced Materials
Binh T Mai, Soraia Fernandes, Preethi B Balakrishnan, Teresa Pellegrino
Combining hard matter, like inorganic nanocrystals, and soft materials, like polymers, can generate multipurpose materials with a broader range of applications with respect to the individual building blocks. Given their unique properties at the nanoscale, magnetic nanoparticles (MNPs) have drawn a great deal of interest due to their potential use in the biomedical field, targeting several applications such as heat hubs in magnetic hyperthermia (MHT, a heat-damage based therapy), contrast agents in magnetic resonance imaging (MRI), and nanocarriers for targeted drug delivery...
May 7, 2018: Accounts of Chemical Research
Yiting Qiao, Jianqin Wan, Liqian Zhou, Wen Ma, Yuanyuan Yang, Weixuan Luo, Zhiqiang Yu, Hangxiang Wang
Cancer remains one of the world's leading causes of death. However, most conventional chemotherapeutic drugs only show a narrow therapeutic window in patients because of their inability to discriminate cancer cells from healthy cells. Nanoparticle-based therapeutics (termed nanotherapeutics) have emerged as potential solutions to mitigate many obstacles posed by these free drugs. Deep insights into knowledge of the tumor microenvironment and materials science make it possible to construct nanotherapeutics that are able to release cargoes in response to a variety of internal stimuli and external triggers...
May 4, 2018: Wiley Interdisciplinary Reviews. Nanomedicine and Nanobiotechnology
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