bluuebunny/crossref_metadata_2025_split huggingface dataset:
Study of Gelation for Biodegradable Polyelectrolytes By a Counter Ion Exchange Approach
Authors: Saito Keita , Yano Shigekazu , Fukushima Kazuki 
Published: February 2020

Cationic polymers are promising as a new class of antimicrobials to combat a threat of emerging drug-resistant superbugs because multiple positive charges are effective in electrostatic interaction with negatively charged bacterial cell membranes, which leads to membrane disruption.1) Since this mechanism is fundamentally different from those of most conventional antibiotics that target inhibition of an intracellular function of bacteria, these antimicrobial polymers are believed not to contribute to development of drug resistance. Originating from the first report by Nederberg et al.,2) a series of biodegradable antimicrobial polycarbonates have been developed, and biodegradability and bioabsorbability have been recognized important for antimicrobials that injection into the body is assumed. We also have recently developed cationic antimicrobial polycarbonates tagging primary ammonium salts and a hydrophobic moiety at the side chains. These polymers exhibit antimicrobial activity and biocompatibility tuned by sequence, composition, and structure of hydrophobic comonomer units.
Moreover, microbial colonization and biofilm formation on biomedical implants and devices are now acknowledged as a more severe threat and cause financial challenges for patients. Bacterial biofilm comprising complex exopolysaccharides matrix is difficult to destroy and thus serves as barriers against antibiotics. Antimicrobial hydrogels are envisioned to be an effective weapon to counter the biofilm problem.3) Biodegradable antimicrobial hydrogels are the current focus of our research because they are expected to be used for both inside and outside of the body, e.g., wound dressings for burn treatment and surface treatment of long-term implants such as catheters.
In this study, we report a simple yet effective approach to generating charged biodegradable hydrogels using a counter anion exchange approach. By using di- or tri-carboxylic acids as a counter anion for a cationic ammonium group as well as a cross-linker, a cationic polymer network may be formed. Preliminary, we have already been successful to switch a counter carboxylate of the cationic polycarbonate. To form hydrogels, physical cross-linking points and balance of (de)hydration should be rationally controlled. Thus, we explore several combinations for cationic copolycarbonates with different compositions and hydrophobic side chains and di- and tri-carboxylic acids as shown in Figure 1. In addition, a chemically crosslinked cationic polycarbonate is examined for comparison.

1) Palermo, K. Kuroda, Appl. Microbial. Biotechnol. 2010, 87, 1605-1615.
2) Nederberg et al., Nature Chem. 2011, 3, 409-414.
3) Li et al., Angew. Chem. Int. Ed., 2013, 52, 674-678.

Figure 1
(Invited) Soft Electronics and Machines with Tough Hydrogels
Authors: Kaltenbrunner Martin 
Published: February 2020

Introducing methods for instant strong bonding between hydrogels and antagonistic materials – from soft to hard – allows us to demonstrate elastic, yet tough biomimetic devices and machines with a high level of complexity [1]. Tough hydrogels strongly attach, within seconds, to plastics, elastomers, leather, bone and metals reaching unprecedented interfacial toughness exceeding 2000 J/m2. Our approach is applicable in rapid prototyping and in delicate environments inaccessible for extended curing and cross-linking. The combination of ionic hydrogels with antagonistic materials such as elastomers, polymers and metals allows to create soft electronics and hybrid machines. We demonstrate stretchable batteries for self-powered soft devices, adaptive lenses, and autonomous electronic skin for triggered drug delivery (Figure 1). We further introduce a new family of biodegradable hydrogels that are able to self-heal and are resistant to dehydration. Soft machines and robots – built from hydrogels with tuned mechanical properties – are designed to be operated in ambient conditions and degrade after use. Besides progressing standalone soft machines, our advances in the synthesis of biodegradable hydrogels bring bionic soft robots a step closer to nature.
[1] D. Wirthl, R. Pichler, M. Drack, G. Kettlgruber, R. Moser, R. Gerstmayr, F. Hartmann, E. Bradt, R. Kaltseis, C. M. Siket, S. E. Schausberger, S. Hild, S. Bauer, M. Kaltenbrunner, „Instant tough bonding of hydrogels for soft machines and electronics”, Science Advances, 3(6), e1700053 (2017).
Caption Figure 1: Hydrogel electronic skin. (left) Concept of a hydrogel smart skin, with a flexible unit bearing power supply, control, readout and communication units, and a stretchable transducer batch. (right) Photograph of an untethered electronic hydrogel with four stretchable heating elements and adjoined temperature sensors strongly bonded to a PVA hydrogel. Battery, control, readout and Bluetooth Low Energy communication electronics are hosted on a flexible circuit board.

Figure 1
(Keynote) Textile-Enabled Wearable Energy Devices
Authors: Zheng Zijian 
Published: February 2020

Wearable electronics is foreseen to be the next major technology after smart phone in the near future. However, most conventional electronic devices are rigid, bulky, and heavy, making them difficult to wear. On the other hand, textiles are materials that have been worn by human beings for more than a thousand years. Textiles are flexible, lightweight, conformal, and highly manufacture-able. This talk will introduce how our research group makes use of fibre and textile for wearable electronics. These fibre-based electronic devices can function as high-performance electronics while maintaining the flexibility, lightweight, permeability, processibility, and even washing ability like textiles. In addition, we also show that fibre-based device can significant improve the electrochemical properties of the devices.
References:
[1] Q. Huang, D. Wang, Z. J. Zheng*, Adv. Energy Mater. 2016, DOI: 10.1002/aenm.201600783.
[2] L. Liu, Y. Yu, C. Yan, K. Li, Z. J. Zheng*, Nat. Commun. 2015, 6, 7260.
[3] Y. Yu, C. Yan, Z. J. Zheng*, Adv. Mater. 2014, 26, 5508­5516.
[4] Y. Yang, Q. Huang, L. Niu, D. Wang, C. Yan, Y. She, Z. J. Zheng*, Adv. Mater. 2017, 160667
(Keynote) Controlling Size and Dispersity in Nanoparticle Synthesis: Some Theoretical Results
Authors: Schmid Friederike 
Published: February 2020

Polymeric nanoparticles are of increasing interest in nanotechnology and nanomedicine. One promising approach to preparing nanoparticles in a controlled manner is self-assembly from solution, e.g., in microfluidic devices. Molecular parameters such as the polymer length and architecture as well as process parameters such as mixing speed and shear rate can be used to control the size and shape of the particles.
Here we use self-consistent field theory and field-based simulations to investigate some of the main physical mechanisms underlying this control. The talk will have two parts.
In the first part, we examine the influence of molecular parameters on the resulting particles, with particular focus on the effect of molecular dispersity. Traditionally, theoretical studies us model systems of idealized monodisperse polymers. In reality, however, most synthetic polymers are inherently polydisperse, and this has a significant impact on the size and dispersity of the nanoparticles.
In the second part, we examine mechanisms of size control by tuning process parameters. We examine the so-called co-solvency method, where a collapse of polymeric nanoparticles from solution is induced by mixing bad solvent into a polymer dispersion. Experimentally, it is found that the particle size can be tuned by varying the mixing speed. We show that this control essentially happens in the initial stage of polymer-solvent demixing and derive scaling laws which are in agreement with experiments. Then, we study the effect of high shear rates on self-assembly. Shear mainly affects the later stages of self-assembly. It can reduce potential barriers for particle fusion and thus assist the production of larger particles. Furthermore, it can induce irreversible shape changes and be exploited to make particles with unconventional shapes.
(Keynote) All-Atomistic Molecular Dynamics Calculation of Impact Fracture of Glassy Polymers
Authors: Fujimoto Kazushi , Shinoda Wataru , Okazaki Susumu 
Published: February 2020

Impact-resistance has been one of the target properties of polymer technology from a view point of their mechanical applications. A huge number of investigations have been done for this very important property. One of the key to understand the impact resistance is to investigate the difference in microscopic behavior between brittle and ductile fractures by comparing two extrema of industrial polymers such as PMMA and PC, respectively. However, in spite of an abundance of information about macroscopic behavior of the impact fracture, little has been known about its microscopic picture. This is from difficulty in experiment for the very rapid phenomena.
Molecular dynamics (MD) calculation has been one of the powerful tools for investigating microscopic behavior of molecular assemblies at an atomistic resolution. However, so far, poor performance of the supercomputers has prevented us from investigating polymers based on all-atomistic MD calculations since the systems are huge. Then, we have been obliged to depend upon coarse-grained models such as Kremer-Grest model and DPD model. But, they are not good at describing chemical character of polymers which is essential for the investigation of fracture.
However, recent very rapid progress of supercomputer technology is going to enable us to investigate polymers based on all-atomistic MD calculations free from phenomenological parameters. The all-atomistic model can describe chemical details of the polymers, which is essential for the investigation of the diversity of polymers. Fracture of the polymers depends much on their chemical details such as main-chain bond breaking and side-chain motions.
In particular, it is very important to include bond fracture in the simulation. Since most of the traditional MD calculations have not included bond breaking explicitly, the calculations couldn’t describe brittle fracture of polymers but always resulted in artificial ductile fracture. The bond fracture can be described using potential function such as Morse-type one. The function can be obtained by high quality quantum chemical calculations prior to the MD calculations.
In the present study, brittle fracture has been investigated for PMMA including bond fracture explicitly. Systems constructed for the simulation mimicked the real system. There, experimental molecular weight distribution, density, radius of gyration, and entanglement molecular weight were reproduced well in the initial configuration prepared for the impact fracture test calculations. The calculations clearly show characteristics of the brittle fracture at a molecular level such as void formation, chain reactions of main-chain bond breaking, and small Poisson ratio.
Coarse-Grained Molecular Dynamics Simulation of Elongational Flow of Polymer Melts
Authors: Murashima Takahiro 
Published: February 2020

Elongational flows in polymer melt are important for polymer processing. For fiber processes, uniaxial elongational flow stretches polymer chains and enhance the strength of the fibers. Biaxial elongational flow makes thin films during film extruding processes. Molecular dynamics (MD) simulation can be useful to understand the microscopic mechanics of polymer chains in elongational flow fields. However, it has been difficult to treat elongational flows in MD for a long time. Extending the Kraynik-Reinelt boundary condition [1] for planar elongational flow, uniaxial and biaxial elongational flow have been succeeded in MD and applied to Lenard-Jones fluid [2,3] and crystallization process of an n-eicosane melt [4]. We have investigated elongational flows of a weakly entangled polymer melt [5].
The highly entangled polymer melt in experiments shows extensional thinning [6] while our previous results show extensional thickening [5]. We investigate a mildly entangled polymer melt and discuss whether the non-linearity of elongational viscosity enhances or not. Moreover, we investigate the elongational viscosities of branched polymer melts.
[1] A. M. Kraynik and D. A. Reinelt, Int. J. Multiphase Flow 18, 1045 (1992).
[2] M. Dobson, J. Chem. Phys. 141, 184103 (2014).
[3] T. A. Hunt, Mol. Sim. 42, 347 (2016).
[4] D. A. Nicholson and G. C. Rutledge, J. Chem. Phys. 145, 244903 (2016).
[5] T. Murashima, K. Hagita, and T. Kawakatsu, arXiv: 1803.01517.
[6] A. Bach, K. Almdal, H. K. Rasmussen, and O. Hassager, Macromol. 36, 5174 (2003).
The Effect of Process Parameters on Impregnation Properties of Pultruded Carbon Fiber Reinforced Thermoplastic Epoxy Composites
Authors: Wongsriraksa Patcharat , Nakai Asami 
Published: February 2020

During the pultrusion process, there are some parameters that effect the impregnation performance of pultruded composites. The pultruded carbon fiber reinforced thermoplastic epoxy composites processing parameter such as pulling speed, resin viscosity, molding temperature of the pultruded composites that have to be considered and pulling speed one of parameter is discussed in this research.
In our previous research, it has been clarified that the carbon fiber reinforced thermoplastic resin fiber composites had not been good impregnation and surface for pultrusion process. The main problem during the processing of carbon fiber reinforced thermoplastic resin composites is the impregnation of the fiber reinforcement with highly viscous resin. The objective of this research is to improve an impregnation performance by using the low viscosity of thermoplastic resin. To achieve this objective, thermoplastic epoxy resin were used instead of thermoplastic resin fiber.
In this research is to studies an effect of pulling speed on impregnation of carbon fiber reinforced thermoplastic epoxy resin composites by using pultrusion technology to produce the hollow shape composite. The effect of pulling speed were evaluated.
Optically Manipulated Bottom-up Growth of Nanopatterned Semiconductor Films
Authors: Carim Azhar I , Batara Nicolas A. , Atwater Harry A , Lewis Nathan S 
Published: February 2020

Bottom-up growth of macroscale Se-Te alloy films displaying nanoscale patterning with significant periodic order was effected via photoelectrochemical deposition. The exact nature of the optical excitation was the determinant of the features sizes, periodicities, anisotropies, and orientations of the nanoscale pattern. Use of linearly polarized light resulted in highly-anisotropic lamellar morphologies with the long axes of the patterns aligned along the E-field vector and increasing the complexity of the polarization input resulted in a concomitant increase in pattern complexity. The pattern periodicity was encoded by the illumination spectral profile. A single periodicity in single spatial direction was only generated even with the use of broadband and multimodal spectral profiles and multiple polarization inputs and the periodicity was found to be sensitive to all investigated tuning of such profiles. Structures with nonequal periodicities in the two orthogonal in-plane directions could also be generated and both periodicities could be independently controlled. Additionally, the anisotropies, subwavelength feature size and periodic nature of the deposits enables the fabrication of optical elements with significant wavelength and polarization discrimination.
The nanopatterning process occurred without the use of any type of physical or chemical templating agents: no photomask, patterned substrate nor surfactants/ligands were used to influence the morphology. Modeling of the growth using a combination of full-wave electromagnetic simulations of light absorption and scattering coupled with probabalistic simulations of mass addition successfully reproduced the experimentally observed morphologies and indicated that morphology development was a consequence of the fundamental light-matter interactions during growth.
Modeling of Spherical Objects Using 3D Printing of Soft and Bio-Compatible Materials
Authors: Yoshida Kazunari , Kawakami Masaru , Furukawa Hidemitsu 
Published: February 2020

A fused deposition modeling (FDM) is widely used as a 3D printing method of plastics (polymeric materials). However, modeling of soft materials is conventionally quite difficult using such method although 3D printing of plastics and/or elastomers is required for medical application such as manufacturing of prosthetic arms.
In this study, we investigated the optimum 3D printing conditions for modeling of spherical objects made with FABRIALTM-R and -H (JSR corp.). First, we 3D printed spherical objects with various nozzle speeds. Then, we observed the surfaces of 3D printed objects using a stereoscopic microscope. In addition, the hardness of the objects was measured by using a durometer (type E, Japanese Industrial Standards). The results suggest that optimum nozzle speed is 2.0 mm/s. In addition, the hardness of FABRIALTM-R object was dependent on nozzle speed while that of FABRIALTM-H was constant. Furthermore, we investigated the dependency of object hardness on pushing direction, vertical to and along stacking plane during printing. The hardness in the case of vertical to stacking plane is lower than that in the case of along stacking plane. These findings are expected to be applied to modeling of parts of prosthetic arms and soft-matter robots.
Electrochemical Deposition of Compact TiO2 Layer for Perovskite Solar Cells
Authors: Nonomura Kazuteru 
Published: February 2020

This presentation is dedicated to the utilization of a compact TiO2 layer in n-i-p perovskite solar cells as blocking and electron transporting layer. The formation of a homogeneous compact TiO2 layer is a key step toward blocking the electron back-reaction between conductive substrate (F-doped tin oxide) and perovskite. In the present study, a compact TiO2 layer was prepared by electrochemical deposition. This method is an alternative to the frequently used alternative of spray pyrolysis commonly used to prepare a compact TiO2 layer.
The electrodeposited TiO2 films were characterized by a variety of methods, including UV-VIS spectroscopy, cyclic voltammetry, X-ray diffraction, and scanning electron microscopy. The electrodeposited TiO2 compact layer was introduced in perovskite solar cells, which were compared with cells prepared with sprayed TiO2 compact layers. The results confirmed that an electrochemically deposited compact TiO2 layer can work sufficiently as a blocking and electron transport layer in perovskite solar cells.
(Keynote) Electrochemical Reactions at Semiconductor Thin Films As Part of Solar Energy Conversion or Advanced Light Management
Authors: Schlettwein Derck 
Published: February 2020

Semiconductor Electrodes play a key role not only in microprocessor technology but also in photovoltaics (PV) and in smart windows (SW). Devices based on classic semiconductors like silicon or tungsten oxide have been well established, matured and led to commercialization and widespread technical application. In this contribution I will focus on the development of alternative material systems offering relevant advantages in function or in the sustainability of energy technologies based on them. As can be expected, however, new challenges are posed by such alternative approaches which will also be tackled in the talk.
Dye-sensitized solar cells (DSSCs), typically based on porous TiO2 as photoanode material represent an alternative to established PV technologies with clear expected advantages in energy payback time and harvest factor because of significantly decreased energy input upon preparation of devices. This trend can be taken to the next level if ZnO crystallized from aqueous solution rather than annealed TiO2 is used. To reach such goal, however, cell efficiencies need to increase beyond the presently reached values. Chemical and photoelectrochemical surface reactions at ZnO, however, need to be overcome in order to realize such progress. Some strategies and recent results from the author´s laboratory will be discussed.
Electrochromic cells (ECs) are essential parts in well established self-dimming rear-view-mirrors for automobiles and in SW for vehicles and buildings. In particular the latter are thought to have a significant potential impact on the human energy consumption since they allow to adjust the amount of transmitted or reflected light and heat radiation into a room depending on the demand in the room and depending on the season and weather conditions to an increased extent compared even to modern multiple-coated window glass. In this context it is of uttermost importance to increase the long-term stability of EC devices which might be reached by use of solid rather than liquid electrolytes which, however, present a substantial hurdle to ion conductivity essential for the devices. Some recent progress will be presented. A different improvement is sought in the rate of switching the transparency. In this respect, organic semiconductor films may present attractive alternatives since thinner films already provide intense absorption and fast switching can be reached which will also be discussed in the talk.
(Invited) Biomimetic Proton Conductive Polymer Electrolyte
Authors: Matsui Jun 
Published: February 2020

Proton conductive polymer electrolyte is one of the key components to fabricate an efficient fuel cell. Perfluorosulfonic acid polymers, such as Nafion are widely used because of their high proton conductivity. It has been considered that a strong acid is important for high proton conductivity therefore many group synthesized acid contain polymer from the viewpoint of how much strong acid can be added with keeping the polymer mechanical strength. On the other hand, living cell, mitochondria also used proton to produce energy. The difference in proton concentration across a membrane produce electrochemical potential energy, which drives the synthesis of ATP. Mitochondria does not contain strong acid and the protons are transferred using weak acid and base, whereas efficient proton conduction occurred at the bilayer membranes. Although the detailed mechanism for the proton conduction at the membrane is still controversial, several groups suggested that protons efficiently conduct through the membrane surface [1].
In this paper, we present a polymer proton conductive membrane which mimic the proton conduction at the bilayer membrane [2]. The polymer membrane was prepared by deposition of poly(N-dodecylacrylamide-co-acrylic acid) monolayer formed at an air-water interface using the Langmuir-Blodgett technique. The membrane was formed by multilayer film of the monolayer, in which formed a clear lamellar structure composed of hydrophobic alkyl side chains and hydrophilic amide and carboxylic acid regions. The hydrophilic region created 2D proton conductive nanospace, which resembles to the bilayer membrane surface. The proton conductivity in the 2D proton nanospace of the biomimetic polymer membrane reached to 5.9×10-2 S/cm, which is comparable to strong acid polymer electrolyte. The achievement of high proton conductivity even using weak acid as a proton source clearly indicates an efficient proton conduction in 2D nanospace. Moreover, we found that acrylic acid groups should be located in a proper distance to achieve the high proton conductivity. The mechanism of proton conduction at the 2D nanospace will be discussed using reported works of theoretical calculation.
References: [1] G. Groenhof et al., Biophys. J.
2014, 107, 76. [2] J. Matsui et al., ACS Appl. Mater. Interfaces
2011, 3, 1394., Mol. Cryst. Liq. Cryst.
2013, 579, 17., Langmuir
2015, 31, 5174., Langmuir
2017, 33, 12897.

Figure 1