bluuebunny/crossref_metadata_2025_split huggingface dataset:
(Invited) Photo Stimuli Responsive Supramolecular Actuators Constructed By Non-Covalent or Topological Crosslinkers
Authors: Takashima Yoshinori 
Published: February 2020

Various kinds of biological molecular motors, such as myosin, kinesin, and dynein, realize the conversion of energy in ATP hydrolysis into mechanical work. These mechanical motions inspired supramolecular chemist to realize polymeric materials with supramolecular materials. Two structural approaches may realize supramolecular actuators through host–guest interactions: a method with a linear main chain and one with a side chain in the polymer structure (Fig. 1).1) We have prepared photo responsive supramolecular actuators by integrating host–guest interactions on the polymer side chains (Fig. 1a). The association and dissociation of inclusion complexes as crosslinking units on the polymer side chains demonstrate contraction and expansion motions due to changes in the crosslinking density. A plate-shaped actuator bent against the incident ultraviolet (UV) light. 2)
Herein we hypothesize that polymer chains crosslinked with [c2]daisy chains would realize a novel supramolecular actuator whose volume contracts upon UV light irradiation but expands upon visible (Vis) light irradiation. This contraction would bend the flat plate actuator toward the incident UV light because UV irradiation causes the shrinkage of the end-to-end distance of the [c2]daisy chain to shrink polymeric materials due to desorption of the solvent on the exposed surface (Fig. 1b). Supramolecular hydrogels containing CD-based [c2]daisy chains as crosslinkers contract and expand through photoresponsive sliding motions of the [c2]daisy chain (Fig. 1c).3) The photogenerated supramolecular artificial muscle is reminiscent of contraction and expansion motions of biological skeletal muscle.

Figure 1. Supramolecular actuators using cyclodextrin derivatives. These supramolecular actuators show macroscopic contraction–expansion and flexing behaviors.

References

(1) Harada, A.; Takashima, Y.; Nakahata, M. Acc. Chem. Res.
2014,
47, 2128-2140.
(2) Takashima, Y.; Hatanaka, S.; Otsubo, M.; Nakahata, M.; Kakuta, T.: Hashidzume, A.; Yamaguchi, H.; Harada, A. Nat. Commun.
2012,
3, 1270.
(3) Iwaso, K.; Takashima, Y.; Harada, A. Nat. Chem.
2016,
8
, 625–632.
(4) Takashima, Y.; Harada, A. J. Incl. Phenom. Macrocycl. Chem.
2017,
87, 313-330.

Figure 1
Real-Time Volume Changes in Individual Hydrogel Microspheres Observed By High-Speed AFM
Authors: Matsui Shusuke , Uchihashi Takayuki , Suzuki Daisuke 
Published: February 2020

Many thermo-responsive polymers show a lower critical solution temperature (LCST), and thus they display a coil-globule transition across the LCST by changing temperature. Hydrogel microspheres (microgels) composed of thermo-responsive polymer are taken over the property from the polymer, as a result, they show a volume phase transition temperature around the LCST. Owing to their rapid temperature-responsiveness, microgels are expected the various application such as sensors and separation technology [1]. Thermo-responsive properties of the microgels have been mainly evaluating by light scattering so far because typical size range of the microgels are tens nanometer to sub-micron order, which can not be clearly observed by optical microscopy. Against this background, the real-time volume transition of individual microgels during heating was visualized for the first time using high-speed atomic force microscopy (HS-AFM) [2]. This method allows the direct visualization of the structural dynamics of biological molecules in action, without significantly disturbing the physiological function of the molecules [3-4], and allows the monitoring dynamic adsorption behavior of microgels onto solid substrate in aqueous solution [5]. The microgels were synthesized from N-isopropyl acrylamide and cross-linker N,N'-methylenebis(acrylamide) with different content by aqueous free-radical precipitation polymerization. In the present study, we will discuss the real-time changes in morphology of the microgels.
Partially reproduced with permission from [5] Copyright (2017) John Wiley and Sons.
References
[1] F. A. Plamper, W. Richtering, Acc. Chem. Res., 50, 131 (2017)
[2] S. Matsui et al., in preparation
[3] T. Ando, T. Uchihashi, T. Fukuma, Progr. Surf. Sci., 83, 337 (2008)
[4] T. Ando, T. Uchihashi, S. Scheuring, Chem. Rev., 114, 3120 (2014)
[5] S. Matsui, T. Kureha, S. Hiroshige, M. Shibata, T. Uchihashi, D. Suzuki, Angew. Chem. Int. Ed., 56, 12146 (2017)
Evaluation of Gel Touch Sensor
Authors: Hara Yuta , Yoshida Kazunari , Ahmed Kumkum , Khosla Ajit , Kawakami Masaru , Furukawa Hidemitsu 
Published: February 2020

The polymer gel is composed of polymeric chains which are crosslinked in a three-dimensional (3D) network structure and liquid which is widely applied to tissue engineering, medical treatment, and solid state electrochemical devices. The gel contains a large amount of water inside the three-dimensional network structure. The human body is also mostly composed of water, hence, the percentage of water in human body is relatively high similar to hydrogel.
Among various kind of gel, ion gel possessing ionic liquid is beneficial for applications since ionic liquids are liquid salts at room temperature and have useful properties such as non-volatility, non-inflammability, electrochemical stability, thermal stability and high ionic conductivity. In this study, we investigated the piezoelectric properties of ion gels to apply them for touch and pressure sensors in soft-matter robotics.
In this study, the used ion gel was made utilizing thiol-ene reaction and was composed of thiol monomer. The thiol-ene reaction is hardly influenced by the surrounding environment, hence, we can easily make ion gel. In addition, it is possible to form any objects using a photopolymerization initiator and a 3D printer. The aim of this research is to develop a tactile sensor using ion gel having non-volatility, non-flammability, thermal stability, high conductivity and softness close to humans.
For the preparation of ion gels, the monomers pentaery thritol tetralcis (3-mercaptobutylate) and dipentaerythritol hexakis (3-mercaptopropionate), crosslinker 1,6-Hexanediol diacrylate, initiator benzophenone, solvent ionic liquid 1 - buty - 3methylimidazolium bis (fluorosulfonyl) imide were used. For the experiment, a friction tester, LCR meter and temperature controller were used.
Here we report the relationship between frequency of applied alternating current, electric resistance of ion gel, applied load, and temperature. The sizes of sample gel plates are 50 mm × 10 mm × 2 mm and 40 mm × 10 mm × 2 mm. Resistance of ion gel in 10 kHz is 3.4 kΩ and 4.8 kΩ taking for 200 g and without loads, respectively. It is speculated that the electric resistance decreased with the shape change due to load application. Resistance of ion gel in 10 kHz is 12.3 kΩ, 5.86 kΩ and 3.48 kΩ at temperature of 40 ℃, 60 ℃ and 80 ℃, respectively. We confirmed the temperature dependency of impedance of the gel sample. The experimental results indicate that impedance was decreased with increase in frequency, load and temperature.
Currently, we are developing a human finger-modeled pressure and temperature sensor. Ion gel is shaped into human finger using a 3D printer. The LCR meter used for resistance measurement is made using Arduino. The technique shown in this study is expected to be applied to soft robot and robot hand.
Antibacterial Property of Cationic Hydrogels
Authors: Shibata Yuki , Kurokawa Takayuki , Aizawa Tomoyasu , Honglei Guo , Gong Jian Ping 
Published: February 2020

【Introduction】
Physical and mechanical properties of a hydrogel, which is soft and has high water content, are similar to those of living tissues. Thus, a hydrogel attracts much interest as material for regenerative medicine and alternatives for human body. These properties of a hydrogel, however, also gives suitable environment for bacteria and mold. Therefore, hydrogel is easily contaminated by bacteria, which becomes a severe problem in their widespread applications. One possible way to solve this problem is use of antibacterial chemical agents. Hydrogels immersed in antibacterial agent aqueous solution can get antibacterial property temporally. However, such agent will gradually flow out and hydrogel lost antibacterial property as time goes on.
To overcome this problem, our strategy is to fix the antibacterial agents into the gel networks. It is known that cationic agent has good antibacterial property. In this time we synthesized a cationic hydrogel from (3-acrylamidopropyl)trimethyl-ammonium chloride and investigate antibacterial property of this hydrogel.
【Experiment】We prepared cationic hydrogel from (3-acrylamidopropyl)trimethyl-ammonium chloride, anionic hydrogel from sodium 2-acrylamido-2-methylpropanesulfonate, and neutral hydrogel from N,N-dimethylacrylamide. We also used agar gels as negative control. The prepared gels were soaked in saline to remove residual monomers for 1 week, and then put in saline including SYTO9 and propidium iodide for 1 day to perform live-dead imaging. E.coli was seeded on these samples, and the samples were put in an incubator(37°C) for 12 hour. After that, E.coli on samples were observed with a fluorescence microscope to calculate fraction of dead E.coli.
【Result】After 12 hours culturing, 86.3 % of E.coli on cationic hydrogel was dead whereas fraction of dead E.coli on the other gels was significantly smaller than that (Figure 1). This result suggests that cationic hydrogel has antibacterial property at least for E.coli.

Figure 1
(Keynote) Wearable Devices and Systems on Textiles for Biomedical Monitoring and Safety
Authors: Gray Bonnie L. , Chung Daehan 
Published: February 2020

Great advances continue to be made in fields such wearable electronics, flexible electronics, functional polymers, and other soft materials. However, much of this research is field-specific, despite the enormous potential that the convergence of these research areas has to revolutionize personalized medicine, worker safety, and biomedical and environmental monitoring. We present our work in developing wearable devices and systems based on the convergence of multiple research areas in order to offer practical solutions for applications such as lighting and health monitors for safety vests; heart and perspiration monitors for athletic clothing; and other applications in real-time wearable bioelectric and biochemical monitoring.
Intense research into wearable electronics results in many innovative devices and systems, e.g.: flexible polymer printed circuit boards (PCBs); roll-to-roll foil and other printed devices; printing and weaving of textiles; and special geometries for flexible interconnect between rigid components. Our lab develops alternative methods, including conductive polymer nanocomposites and metal transfer processes for wearable bioelectric sensors. We present textile-based wearable devices and systems for electrocardiogram (ECG), tissue impedance, and pressure sensors. Unlike many other techniques, our technologies and materials are highly compatible with clothing-based textiles, and result in non-polarizable electrodes for improved frequency response.
Traditionally, biofluid-based biomedical sensors are fabricated in rigid substrates or flexible materials such as polydimethylsiloxane (PDMS) that are bonded to rigid substrates. Free-standing flexible devices are developed for, e.g., perspiration sensors; however, such processes typically require long fabrication times, equipment in a cleanroom facility, and difficulty with integration onto textiles. Other devices employ porous materials to deliver biofluids, e.g., perspiration, by capillary forces; however, such devices are limited in fluid collection and suffer from evaporation issues. To overcome these and other limitations of current devices, we present printing-based fabrication processes that employ screen printable ink for biomedical sensors for biofluid analysis. These devices and systems can be fabricated on textiles that can be laundered, facilitating rugged wearable devices and systems for biomedical and environmental monitoring.
Self-Toughening of Double Network Hydrogels By Using Bond Rupture-Induced Radical Polymerization
Authors: Namba Ryo , Matsuda Takahiro , Nakajima Tasuku , Nonoyama Takayuki , Kurokawa Takayuki , Gong Jian Ping 
Published: February 2020

【Introduction】
Artificial materials are locally damaged and deteriorated when subjected to a long-term mechanical loading. Such local degradation of materials sometimes causes destruction of the material and severe accidents. Therefore, control of material deterioration is important for realizing a safe and secure society. On the other hand, in living tissues such as muscles, the damaged tissue structure is repaired and strengthened spontaneously through metabolism. In this study, we realize a system in which a new polymer network spontaneously polymerizes at a deteriorated site in hydrogels inspired from the metabolism of living tissues. The aim of this study is to create artificial materials that spontaneously repair degraded parts and further toughen themselves.
In order to achieve the above object "spontaneous polymerization of new polymer network at the deteriorated part", we focused on the Double Network (DN) gel developed in our laboratory. A DN gel exhibits high toughness despite 90% of water content. A DN gel is composed of two types of network with opposite physical nature, rigid and brittle first networks and soft and ductile second networks. Such contrasting double network structure make a DN gel so tough(1). In recent years, it was found that when mechanical load is applied to DN gel, covalent bonds of brittle first network are preferentially broken at loading part (degraded part), and a large amount of radical (mechanoradical) is generated. Utilizing this knowledge, in this study, by addition of a radical-polymerizable monomer/crosslinker to the DN gel, we aim to realize restoration and further toughening of the damaged DN gels through new polymer network synthesis from the radicals generated at the broken end of polymer chain (Fig. 1).
【Result】
A DN gel polymerized by a conventional method was immersed in a solution containing 2-acrylamido-2-methylpropane-sulfonate sodium salt (NaAMPS) as a monomer and N,N'-methylenbisacrylamide (MBAA) as a crosslinking agent. By applying tensile deformation to the DN gel, new polymer network was successfully synthesized at the stressed part. The tensile test of the stressed DN gels (Fig. 2) confirmed that both the fracture stress and the fracture strain greatly changed, and the work of extension, which shows the toughness of materials, was improved after tensile deformation.
【References】
1) J. P. Gong et al.,
Adv. Mater.,
2003, 15, 1155-1158

Figure 1
Analysis of Internal Structural of 3D Printed Shape Memory Gels
Authors: Shiblee MD Nahin Islam , Rahman MD Sazzadur , Ahmed Kumkum , Kabir M. Hasnat , Khosla Ajit , Furukawa Hidemitsu 
Published: February 2020

Understanding the internal structure of the gels is important to comprehend their physico-chemical properties and propose better utilization in practical application. The scanning microscopic light scattering (SMILS) is one of the powerful tools to nondestructively characterize the internal structure of gels. The SMILS is a typical dynamic light scattering (DLS) system, which can be used to characterize the internal structure of gels by observing the diffusion process [1]. In our previous study we studied internal structures of Poly (N-N-dimethylacrylamide (PDMAAm) gels and different inter-crosslinking network (ICN) gels and compared their crosslinking density with ionic gels [2]. We also determined the soft to hard transition temperature of PDMAAm-co Stearyl acrylate (SA) shape memory gels SMGs prepared by mold techniques by carrying out temperature dependent SMILS measurements [3].
In this work, we present the structural analysis of 3D printed transparent SMGs containing two different hydrophobic crystalline monomers SA and Lauryl acrylate (LA) fabricated by optical stereolithography technique. By SMILS we can obtain a time- and space-averaged correlation function i.e., an ensemble-averaged correlation function to overcome the inhomogeneous media. For each sample, the time-averaged homodyne correlation functions g(2)(q,τ) were determined at several points, where q is scattering vector and τ is correlation time. Then the ensemble-averaged correlation function g(1)(q,τ) was calculated. Thus, the characteristic size of diffusing objects (mesh size) ξ can be estimated from the Einstein-Stokes formula. In the measurement of the SMGs, we controlled the angle of PMT and relaxation time distribution was calculated for every angle. We have correlated their internal structures with mechanical properties to understand their internal structures and made justified assumption on their structural homogeneities.

H., Horie, K., Nozaki, R., Okada, M. Phys Rev E 68:031406-1-14 (2003)

Ahmed, K., Watanabe, Y., Higashihara, T. Arafune, H. Kamijo, T., Morinaga, T. Sato, T., Makino, M. Kawakami, M., Furukawa, H. Microsyst Technol., 22, 17 (2016)

Kabir, M., H., Gong, J., Watanabe, Y., Makino, M., Furukawa, H.
Lett., 108, 239–242 (2013)
TEM Observation of Nano-Scale Hydrogel Network Structure
Authors: Kiyama Ryuji , Nonoyama Takayuki , Nakajima Tasuku , Kurokawa Takayuki , Gong Jian Ping 
Published: February 2020

Hydrogel, containing large amount of water inside its polymer network, is one of the most attractive biomaterials, because of its similarities with living tissues such as, high water content, low friction and flexibility. These unique features come from complicated polymer network structure, and until now great effort have been put in to clarify nano scale structure of hydrogel. Especially, many researchers tried to investigate by using scattering techniques. However, scattering data just presents limited information in reciprocal space and “real” polymer network structure is still not well understood due to difficulty on direct observation of hydrogel polymer.
In this study, we adopt an idea to stain polymer network by using inhomogeneous nucleation, nucleation starts from the functional group of additive. If we carried out inhomogeneous nucleation in the hydrogel, mineral crystals easily forms complex with hydrogel network and this mineral distribution should represent the original polymer structure. Therefore, the purpose of this study is to stain hydrogel polymer network with mineral and to observe its nano-scale structure by using transmission electron microscope (TEM).
Double network hydrogel was synthesized by two step UV radical polymerization.1 2-acrylamido-2-methyl propanesulfonic acid (AMPS), which contains sulfonic functional group, was used for 1st polymer network. Then, mineral bernalite (Fe(OH)3), whose nucleation accelerates by sulfonic group, was mineralized into DN gel. Fig.1 shows TEM image of mineralized DN gel and its schematic image. Nano scale hydrogel polymer network structure was successfully observed and this structure well agreed with previous prediction from neutron scattering method. This is the world’s first direct observation of polymer network. Mineralized crystal size was several nm in diameter, which is same scale of polymer blob. It indicates that we observed mineral crystals surrounded by individual polymer blobs. The detailed results will be presented in conference. In conclusion, we succeeded direct observation of hydrogel polymer network using TEM. This is a very challenging study not only for understanding hydrogel, but also for visualization polymer network, which is one of biggest dream of polymer scientists.

References

[1] J.P. Gong et al., Advanced Materials, 2003, 15, 1155–1158.

Figure 1
(Invited) Flexible and Printable Organic Solar Cells for High-Performance and Stable Operation
Authors: Fukuda Kenjiro , Someya Takao 
Published: February 2020

Abstract
Efficient, stable and flexible organic solar cells can deliver energy in an environmental friendly way and offer great potentials as portable and compact power sources. All state-of-the-art organic solar cells are at present processed on rigid substrates with limited active area. Attempts to process organic solar cells on flexible plastics using printing technology often result in inferior performance, due to imperfect interface, undesired delamination or intricate processing. We are trying to solve these problems from various view point By checking each material itself and process, both high power conversion efficiency and high stability can be achieved. In this talk, we will discuss how to achieve high efficient and water-proof [1], thermally stable [2], and mechanical robust [3] solar cells on flexible substrates.

Jinno, H. et al.
Nat. Energy
2, 780–785 (2017).

Xu, X. et al. doi:10.1073/pnas.1801187115 (2018)

Jiang, Z. et al., Adv. Mater. Accepted.

Figure 1
(Invited) The Challenge of Shaping Ideas into Applications: The Multi-Competences Approach in Industrial Innovation
Authors: Albunia Alexandra Romina , Gloger Dietrich , Hristov Velichko , Liu Yi , Stockreiter Wolfgang 
Published: February 2020

The number of application fields of polymeric materials has impressively broadened over the few decades following the implementation of industrial polymerisation production processes. Synthesis of new polymers or a more advanced control of the molecular design of polyolefinic materials has often driven the technological innovations that are at the base of our modern society.
The production of polymer based goods at industrial level is an extraordinary example of multidisciplinary collaboration. Either starting from designing new materials, or starting from the property requirement of the end application, the original idea needs to develop based on the knowledge of the material properties, of the technology enabling its synthesis, and of the processing conditions to transform it into the required application. In fact, driving the innovation of polymeric materials and applications requires the understanding of the structure-property relationships along the whole value chain and a sound knowledge of physical and chemical processes at many different scales.
In this perspective, new developments pull for a closer cooperation of experts from different fields and for a smarter use of the resources, including a systematic design of experiments, the increased access to modelling tools to understand and predict processes and phenomena, and a better use of the full set of data available (digitalisation).
Recent material developments have been possible in Borealis following such multi competences approach and some selected cases will be presented.
It will be shown, for example, how the development of polypropylene fiber reinforced materials, and in particular long glass fibers (PP-LGF), is based on the ability to monitor the major parameters correlating with the mechanical performance, namely the final fibre length, the distribution, and the orientation, throughout production and conversion of reinforced, injection moulded polymer parts for automotive applications. The possibility of material modelling for understanding how to influences fiber length during production and conversion allowed to establish a guideline of best practice to get the maximum out PP-LGF.
It will be also shown how modelling of film production process parameters can be used for understanding how to influence the structure and morphology generated in thin films, and how this might be correlated to the electrical insulation and anti-cling properties of the BOPP (biaxially oriented polypropylene) dielectric layer in capacitors.
As third example, the correlation between multimodal polymer design, crystallisation conditions and pressure pipe performance will be presented, discussing how modelling the entangled polymer network would help in predicting the pressure pipe life time.