Day 1 :
Keynote Forum
Diane R Bienek
ADA Foundation, USA
Keynote: Multifunctional polymeric materials for dental restorations
Biography:
Diane R Bienek has 15+ years of experience conducting translational science in the Biomedical and Dental field. A primary focus has been to establish applied research and product development studies designed to improve patient care by advancing point-of-care technologies for mitigating and treating post-operative complications. At the ADA Foundation, Volpe Research Center, she is part of an interdisciplinary team for the advancement of bioactive polymeric materials. To ensure biocompatibility of novel antimicrobial dental materials, her recent efforts include conducting in vitro toxicological assessments on eukaryotic cell types associated with the oral cavity
Abstract:
Statement of the Problem: Polymeric resin-based materials are commonly used in dental restorations. A trend for the next generation is to incorporate multifunctional capabilities to regulate microbial growth and re-mineralize tooth surfaces. Our ongoing, NIDCR-supported research (DE026122) focuses on simultaneous incorporation of novel quaternary ammonium antimicrobial acrylic co-monomer (QA-MA) and bioactive amorphous calcium phosphate (ACP) filler into urethane-based (UDMA) resins. While a sustained release of re-mineralizing calcium (Ca) and phosphate (P) ions is a desired feature in restoratives, the potential leaching of unreacted monomers and other products can lead to clinical failure. We assessed Ca and P ion release (remineralization potential) of ACP filler and in vitro cytotoxicity of QA-MA in gingival cells.
Methodology: ACP and Bis(2-methacryloyloxy-ethyl) dimethyl-ammonium bromide (IDMA) were synthesized and their structure confirmed by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction analysis (XRD), and/or 1H-nuclear magnetic resonance spectroscopy (1H-NMR). Ion release studies employed inductively coupled plasma-atomic emission spectroscopy (ICP-AES). Direct contact cytotoxicity tests were performed per ISO10993-5. Gingival fibroblasts (HGF) and keratinocytes (Gie-No3B11) were exposed to two-fold serial dilutions of IDMA (≤1.6 μmol) and methacrylic acid (≤12 mM) as a degradation product. After 24 and 72 h, cells were assessed for viability and metabolic activity.
Findings: The ACP filler and IDMA were successfully synthesized and characterized by XRD/FTIR/ICP-AES and FTIR/NMR, respectively. A desired remineralization potential of ACP fillers has been achieved: supersaturated solutions with Ca/P of 1.66 are conducive to tooth mineral re-deposition (Fig. 1). IDMA concentration did not exert a significant effect on HGF viability or metabolic activity (Fig. 2). However, an effect (P<0.001) of time was observed on metabolic activity (~20% lower after 72 h).
Conclusion & Significance: ACP and IDMA were successfully synthesized. Bio-testing prior to comprehensive physicochemical and mechanical evaluations ensures that the QA-MA’s potential cytotoxicity is carefully balanced with the antibacterial activity.
Keynote Forum
Joseph D Lichtenhan
Hybrid Plastics Inc., USA
Keynote: POSS® epoxy and acrylic additives for optical coatings
Time : 11:10-11:50
Biography:
Joseph D Lichtenhan is a Co-Founder of Hybrid Plastics Inc. and served at its CEO and President for 18 years. He is a pioneer and world authority in the field of POSS® additives. POSS has been hailed as the first entirely new chemical class of monomers to be developed since 1955. His insights into their commercial utility launched the global sales for POSS® in 1998. He has excelled at technology transition and the establishment of a global footprint for POSS® via innovative sales and marketing techniques
Abstract:
The polymer industry and its products are primarily based on a limited pool of hydrocarbon feedstocks that were last advanced in the 1950's with the development of arene-based monomers. Since then, it has become axiomatic in the polymer industry to regard the development of new resins as too capital-intensive, and fraught with risk with regard to ultimate market acceptance. Furthermore, the imperatives for manufacturing to maintain, economics, quality, supply chain integrity, and global EH&S registrations, distribution, and a “heritage” psychology further restrict the commercialization of new polymer technology. Juxtaposed with the above philosophy is the reality that the search, and pull for new polymeric technology by formulators and product manufacturers is intense and the rewards from new chemical and polymer ingredients is economically and technically large. In response to this need, families of POSS® chemical additives were industrialized. Each POSS cage melds the desirable thermal stability, modulus of inorganic additives (SiO1.5) with organic (R) compatibility to render utility with heritage polymers, resins, monomers and ingredients.
In light of the interest spectrum, POSS epoxy and acrylic coating additives provide a simple to use tool-kit that that requires only small loading levels of POSS to favorably improve traditional formulations. At only 1.5 nm in diameter, POSS cages provide a large amount of surface area and volume control when incorporated into formulations. The control of surface area and volume in coatings leads to improved flow, adhesion, environmental durability and effects ranging for optical clarity, low friction, low surface energy and compatibility of key ingredients. The mechanism of action of POSS additives in optical coatings, along with its comparative performance relative to common ingredients will be presented.
Keynote Forum
Kazuo Akagi
Ritsumeikan University, Japan
Keynote: Helical structures and chiroptical properties of multifunctional conjugated polymers
Time : 12:10-12:50
Biography:
Kazuo Akagi has completed his PhD from Kyoto University in 1980. He has received the title of Professor Emeritus from University of Tsukuba (2009) and Kyoto University (2017). He is now an Eminent Research Professor of Ritsumeikan University. He was awarded The Divisional Award of The Chemical Society of Japan (1999), NISSAN Science Prize (2000), Tsukuba Prize (2001), The Award of the Society of Polymer Science, Japan (2002), The Commendation for Science and Technology by MEXT, Prizes for Science and Technology (2005), The Award of the Japanese Liquid Crystal Society (2010), and The Chemical Society of Japan Award (2017).
Abstract:
Conjugated polymers have been attracting current interests because of their peculiar structures and optoelectronic properties. Hierarchically assembled conjugated polymers are anticipated to exhibit highly enhanced helical structures and chiroptical properties. Dynamic controls of helical sense and circular polarization using external stimuli are of particular interest from aspect of next-generation multifunctional materials useful for electronic and photonic applications. Herein, we present current advances in multifunctional materials constructed with hierarchically assembled conjugated polymers with photoresponsive helical sense and circularly polarized luminescence; (i) circularly polarized blueπluminescent spherulites consisting of helically -stacked ionic conjugated polymers, (ii) photochemically switchable RGB and white illuminants based on conjugated polymer nanospheres, (iii) liquid crystallinity-enforced chirality transfer from chiral mono-substituted polyacetylene popolymer to poly(para-phenylene ethynylene), and (iv) switching of circularly polarized luminescence of chiral conjugated polymers by selective reflection of chiral nematic liquid crystals. The mixture of a cationic poly (para-phenylene) derivative and an anionic chiral binaphthyl derivative forms a hierarchically self-organized assembly π with an interchain helically-stacked structure stabilized by the presence of both electrostatic and π_π interactions. The electrostaticπ and _π interactions are essential to the stability π of the -stacked structure, resulting in large dissymmetry factors of in absorption and luminescence. It was demonstrated that the polymer assemblies further gathered to form stacked structure stabilized by the presence of both electrostatic and factors of in absorption and luminescence. It was demonstrated that the polymer assemblies further gathered to form spherulites, which can be regarded as semi-crystalline nanospheres, which exhibit circularly polarized blue luminescence Chiral mono-substituted polyacetylene copolymers, consisting of a liquid crystalline and a chiral monomer unit, were synthesized. The synergistic effects between the liquid crystalline and chiral monomer units were utilized to enable the chirality transfer from the copolymer to an achiral conjugated polymer. The liquid crystallinity-enforced chirality transfer from the copolymer to achiral conjugated polymers was demonstrated.
- Polymer Synthesis and Polymerization | Functional Polymers | Bio-related Medical Polymers | Polymer Nanotechnology | Biochemical Degradation of Polymers
Location: Texas D
Session Introduction
Gyu Leem
University of Texas at San Antonio, USA
Title: Polymer chromophore-catalyst assembly for solar fuel generation
Biography:
Gyu Leem earned his B.S. in chemical engineering from the Hanyang University and Ph.D. in Chemistry from the University of Houston in 2008. After completing his Ph.D., he spent three years working as a principal scientist at LG R&D in South Korea. He was responsible for the design and synthesis of high-performance water absorbing polymer materials for baby diapers. In 2012, he moved to the University of Florida and performed postdoctoral research with Professor Kirk S. Schanze as a part of University of North Carolina Energy Frontier Research Center: Center for Solar Fuels, an Energy Frontier Research Center. He is currently appointed assistant professor of research at the chemistry department at the University of Texas at San Antonio in 2017. His research is focusing on water oxidation, carbon dioxide reduction, and DSPEC water splitting and proton reduction
Abstract:
Statement of the Problem: The polymer industry and its products are Dye-sensitized photoelectrochemical cells (DSPECs) convert energy from the sun directly into fuel. The DSPEC approach is a hybrid based on molecular light absorption and excited state electron or hole injection into the conduction or valence bands of high band gap semiconductors. Toward fabricating DSPEC devices, we have reported polymer-based ruthenium(II) polypyridyl chromophore-catalyst assemblies on TiO2 by using a Layer-by-Layer (LbL) self-assembly process for light driven water oxidation. The photophysical and electrochemical properties of the polychromophore-catalyst assembly were characterized in a solution and at the semiconductor interface and the energy/electron transfer processes were investigated in the polymer assembly. Importantly, photocurrent measurements of the polyelectrolyte LbL films formed on mesoporous semiconductor substrates demonstrate a clear anodic photocurrent response, coupled with the observation of O2. Also, we developed LbL polyelectrolyte assemblies consisting of an anionic π-conjugated poly(isoindigo-co-thiophene) (Pilt) and polyacrylic acid stabilized Pt nanoparticles (PAA-Pt) as proton reduction catalyst, co-deposited with poly(diallyldimethylammonium chloride) (PDDA) as an inert polycation. LbL self-assembly occurs by the alternate exposure of a metal oxide substrate to solutions of oppositely charged polyelectrolytes. UV-visible absorption spectroscopy reveal that multilayer deposition progressively increases the film thickness on ITO substrates. A photocurrent measurement of ITO//(PDDA/Pilt)10(PDDA/PAA-Pt)10 under AM 1.5 illumination and applied bias - 0.4 V shows a photocurrent response. This result provides new guidance for the LbL self-assembly of polychromophores/catalysts for light driven solar-fuels photoelectrochemical systems.
Sungjin Park
Inha University, Republic of Korea
Title: Single molecular-based active species on carbon-based nanomaterials for ethylene polymerizations
Biography:
Sungjin Park has completed his PhD from KAIST, South Korea and Postdoctoral studies from Northwestern University and University of Texas at Austin, USA. Presently, he is an Associate Professor at Inha University, South Korea. His group is working on nanochemistry and various catalytic applications. He has published more than 80 papers in reputed journals
Abstract:
Chemical designing on nanomaterials in molecular level would be a promising route to create new hybrid materials and to control various properties of nano- and molecular materials. Organometallic compounds have been a center of molecular catalysts with preeminent catalytic activity and selectivity in a wide range of chemical transformations. As carbon-based nanomaterials, such as graphene-based materials, carbon nanotubes and carbon nitrides are sterically bulky and they exhibit a wide spectrum of electrical properties, they can dramatically tune the catalytic behavior of transition metal-based active species. Hybridization of organometallic complexes with graphene-based materials can give rise to enhance catalytic performances. In this presentation, I will discuss my recent research activities on the fundamental chemistry of carbon-based nanomaterials as well as catalytic applications.
Zhongjie Ren
Beijing University of Chemical Technology, China
Title: Pendant homopolymer and copolymers as solution-processable thermally activated delayed fluorescence materials for organic light-emitting diods
Biography:
Abstract:
Summary
This study reports a series of polymers with an insulating backbone and varying ratios of 2-(10H-phenothiazin-10-yl)dibenzothiophene-S,S-dioxide as a pendant TADF unit. Green emitting OLED devices employing these polymers as spin-coated emitting layers give high performance.
Introduction
Organic light-emitting diode (OLED) devices have been in continous development since the early 1960s. To improve the external quantum efficiency (EQE) of OLEDs, extensive studies have focused on synthesizing new emissive materials. One of the most important challenges in this field stems from the fact that fluorescent materials harvest emission only from singlet excitons and thus have the limitation of reaching a maximum internal quantum efficiency (IQE) of 25%, whereas statistically 75% triplet excitons are wasted. Metal-free, thermally activated delayed fluorescence (TADF) materials are considered to be third-generation emitters for OLEDs.1-3 Polymeric TADF emitters are particularly suitable for solution processing technologies. However, synthesizing TADF oligomers and polymers is challenging and there are no clear guidelines for their optimal molecular structures. Firstly, simultaneously achieving a small energy splitting between the singlet and triplet states (ΔEST) and suppressing internal conversion is very difficult in molecules containing numerous atoms. Secondly, the triplet population in polymers is easily quenched by intramolecular and intermolecular triplet-triplet annihilation.4 However, there are only a few reported examples of polymeric TADF materials.
Discussion
A series of polymers with an insulating backbone and varying ratios of 2-(10H-phenothiazin-10-yl)dibenzothiophene-S,S-dioxide as a pendant TADF unit, copo1, copo2, copo3 and homopo, have been synthesized and characterized successfully. They exhibit good film forming ability, high thermal decomposition temperatures and suitable glass transition temperatures. Steady-state and time-resolved fluorescence spectroscopic data confirm the efficient TADF properties of the polymers. Styrene, as a co-monomer, is shown to be a good dispersing unit for the TADF groups, by greatly supressing the internal conversion and triplet-triplet annihilation. Increasing the styrene content within the copolymers results in relatively high triplet energy, small energy splitting between the singlet and triplet states (DEST) and a strong contribution from delayed fluorescence to the overall emission. Green emitting OLED devices employing these polymers as spin-coated emitting layers give high performance, which is dramatically enhanced in the copolymers compared to the homopolymer. Within the series, copo1 with a regiorandom ratio of 37% TADF units : 63% styrene units displays the best performance with a maximum external quantum efficiency (EQE) of 20.1% and EQE at 100 cd m-2 of 5.3%.
Conclusions
In summary, a series of pendant polymers with 2-(10H-phenothiazin-10-yl) dibenzothiophene-S,S-dioxide as TADF units and insulating styrene units as side chains have been synthesized and structure/property/OLED performance relationships have been established. Photophysical data confirm that for all the polymers the reverse intersystem crossing mechanism is able to compete with internal conversion and triplet-triplet annihilation. The effect of styrene content on the properties of the TADF properties of the polymers has been evaluated. The triplet energy and the delayed fluorescence contribution increases with increasing styrene content of the copolymers; meanwhile, the energy splitting between the singlet and triplet states (DEST) decreases with reducing styrene content of copolymers. OLED devices based these polymers as spin-coated emitting layers gave high performance, which is enhanced for the copolymers compared to the homopolymer. The best EL performance was achieved for the copo1-based device with CEmax of 61.3 cd/A, PEmax of 40.1 lm/W, and EQEmax of 20.1%. To our knowledge this is the highest EQE reported to date for a TADF polymer.26-30 Furthermore, at 100 cd m-2 the EQE was 5.3%. High EQE, even at very low luminance, is widely recognized as an important figure-of-merit for OLED efficiencies.38 The key molecular features we have developed in this work, namely a non-conductive polymer backbone with pendant TADF units separated by non-emissive units, should be versatile for the design of new families of TADF polymers. It remains to be seen if polymers, which have the potential benefits of high thermal stability, good film-forming ability and reduced phase separation, can be widely exploited for color tuning and enhanced TADF-OLED performance.
Ming-Qiang Zhu
Huazhong University of Science and Technology, China
Title: Geminal cross-coupling polymerization for multiple topological conjugated polymers
Time : 15:05-15:30
Biography:
Ming-Qiang Zhu has his expertise in Optoelectronic Polymer Chemistry, Super-Resolution Fluorescent Imaging, Fluorescent Sensors as well as their application in Biomedical Engineering. He is a Professor of Chemistry and Optoelectronics in Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan, China
Abstract:
The cross-coupling reactions have been used in general C-C bond formation to develop new π-conjugated molecular topological configurations, which is an essential objective for material chemists and can be used extensively in optoelectronic devices such as chemical biosensing, organic light emitting diode (OLED) and organic photovoltaics. Here, we report the general twofold germinal cross-coupling (GCC) for C-C bond formation at 1,1-dibromoolefin over heterogeneous Pd catalysts for multiple π-conjugated molecular topological configurations. We employ a series of recipes from a library of precursors to produce π-conjugated macrocyclics, conjugated dendrimers, linear conjugated polymers, mesoporous conjugated polymer nanoparticles and 2-3 dimensional conjugated covalent organic frameworks (COF). This universal strategy toward specific π-conjugated molecular topological configurations enables efficient coupling of aryl bromides with various coupling partners with high activity and selectivity under mild conditions. The π-conjugated macrocyclics, dendrimers and 1-D polymers show featured molecular assembly and fluorescence properties. 2D and 3D covalent organic frameworks show excellent N2-adsorption and catalytic activity and recyclability in heterogeneous Suzuki-Miyaura cross-coupling reaction.
Biography:
Joseph D Lichtenhan is a Co-Founder of Hybrid Plastics Inc. and served at its CEO and President for 18 years. He is a pioneer and world authority in the field of POSS® additives. POSS has been hailed as the first entirely new chemical class of monomers to be developed since 1955. His insights into their commercial utility launched the global sales for POSS® in 1998. He has excelled at technology transition and the establishment of a global footprint for POSS® via innovative sales and marketing techniques.
Abstract:
Statement of the Problem: The major cause of battlefield mortality and morbidity is uncontrolled hemorrhage, with non-compressible wounds particularly to blame. Many attempts have been made to find a product or device that fulfills the Armed Forces designation of a "perfect" hemostat, but little success has been achieved.
POSS (polyhedral oligomeric silsesquioxane) additives provide unique opportunities to rationally control permeation, transport and surface modification of both man-made and biologically relevant materials. POSS enhanced medical and personal care products have been in the UK and US markets for several years. This presentation will highlight POSS® as a hemostatic device.
Recently we conducted preliminary tests on the in vivo hemostatic capabilities of a syringible semi-liquid elastomer. We demonstrated hemostatic properties in vitro, and found the POSS formulation exhibits many of the desired properties of an ideal hemostat. Additionally, we observed that POSS reduced or stopped hemorrhage in what currently is known as the standard Armed Forces porcine model of uncontrolled hemorrhage.
The mechanism of action of the POSS viscoelastic hemostat, along with its comparative performance relative to other hemostatic agents will be presented
Hongcai Gao,
The University of Texas at Austin, USA
Title: Polymer electrolytes for solid-state sodium batteries
Biography:
Hongcai Gao has completed his PhD from Nanyang Technological University and started his Postdoctoral studies in 2013 at the University of Texas at Austin with Prof. John B. Goodenough. His research is focused on the synthesis of polymer electrolytes for solid-state rechargeable batteries. He has published more than 20 papers in reputed journals
Abstract:
Abstract
The extensive availability of sodium motivates the development of low cost sodium batteries for large scale applications such as powering an electric road vehicle or stationary storage of electric power generated by variable wind or solar energy. However, the use of flammable liquid electrolytes has safety issues, especially in large-scale batteries. The ability to plate/strip a sodium anode reversibly makes possible a safe, low cost rechargeable battery provided a suitable sodium ion electrolyte interphase between the solid electrolyte and a solid insertion compound cathode host can be developed. Gel polymer and plastic crystal sodium ion electrolytes are shown to provide the needed electrolyte/cathode interface to provide all solid state cells of long cycle life and adequate rates at 60 °C