Special Seminars

Thursday, July 3, 2014
10:45 a.m.

Room 130
Polymer Engineering Academic Center

Dr. Wan Kai Chan, Assoc. Dean
Department of Chemistry, The University of Hong Kong
Associate Dean of Faculty of Science

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"Metal Containing Polymers: Design, Synthesis, and Their Opto-electronic Properties"

In this seminar, the use of metal containing conjugated polymers for optoelectronic applications will be presented. In recent years, the majority of research work on organic optoelectronics has been focused on molecular/polymeric conjugated organic molecules. Polymers functionalized with transition metal complex have received relatively little attention. We have developed different series of metal containing polymers functionalized with the polypyridine complexes of rhenium and ruthenium, which may serve as the photosensitizers, light emitters, or charge carriers. Both the conjugated backbone and metal complexes play important roles in light absorption and emission processes. Incorporation of metal complex moieties at the conjugated systems resulted in a strong perturbation of the electronic structures of the molecules. Low bandgap metal containing polymers with optical absorption in the near infrared region were developed by introducing rhenium metal to ligands that exhibit intramolecular charge transfer character. In the second part of the talk, the synthesis of metal containing multifunctional block copolymers for the fabrication of polymer-carbon nanotube hybrid materials will be presented. These polymer-nanotube hybrids were characterized by electrostatic force and photoconductive atomic force microscopies. An enhancement in photocurrent response was observed after introduction of a photosensitive polymer on the carbon nanotube surface. The electronic interaction between the polymer and carbon nanotube was also studied by time-resolved transient absorption spectroscopy.

Biography:
Dr. Wai Kin Chan received his B. Sc. degree (major in chemistry) from the Chinese University of Hong Kong in 1991 and Ph.D. degree from the University of Chicago in 1995. He joined the University of Hong Kong as a faculty member in 1995, and is currently serving as the Professor of Chemistry and Associate Dean of the Faculty of Science. His research has been focused on the development of metal containing polymers with interesting optoelectronic properties, and the synthesis of multifunctional metal containing polymers by new polymerization methodologies. He has published more than 180 research papers and 4 book chapters.


Friday, June 20, 2014
10:00 a.m.

Room 130
Polymer Engineering Academic Center

George Fytas
Max Planck Institute for Polymer Research, Germany
Department of Materials Science, University of Crete and IESL-FORTH, Greece

DOWNLOAD: Click here to download the full abstract flyer

"Versatile Light-Actuated Matter Manipulation in Transparent Polymer Solutions"

Complex fluids have attracted attention owing to their intricate response to optical fields. Despite the vivid interest, several relevant aspects still remain unclear. A mysterious light-soft matter coupling is the unexpected material organization along a cw-visible laser beam, observed in homogeneous entangled solutions of 1, 4-polydienes [Science 2002]. When irradiated with mild (few mW) laser light, the non-absorbing solutions respond by a local polymer concentration increase. The increase of the local refractive index δn alters in turn the light propagation and the resulting self-focusing optical nonlinearity led to the formation of various micro-patterns, such as soliton-like single and multi-filament arrays, and gratings, depending on the irradiation conditions [JACS 2005,Opt.Lett.2008].
In the recent years we extend further the phenomenology of this light-matter effect. The sign of δn is not necessarily related to the optical contrast Δn [Soft Matter 2012]. Depending on the solvent, the polymer chains could be either effectively attracted or repelled by visible laser light, irrespectively of Δn. All possible material responses to light have been of observed; polymers dissolved in good solvents of higher or lower refractive indices could be accumulated in the irradiated volume or be dispersed outside it. The writing efficiency exhibited strong wavelength dependence for the solutions with δn>0. Under similar experimental conditions, it occurs fast in the red (λ=633-671 nm), slows significantly down towards blue (λ=532 and 488 nm), and ceases at λ=830 nm. The effect is not limited to homopolymers only. In transparent dispersions of a polystyrene-b-polyisoprene (PS-b-PI) in hexane, irradiation led to copolymer-rich fibres. Turbid dispersions of the same copolymer in ethyl acetate revealed a unique case of self-induced transparency [Opt.Lett 2012]. The PI-light coupling and the metastable character of the dispersion are believed to be at the origin of the effect.
In contrast to electrostriction, the sign of the refractive index difference Δn between the polymer and the solvent does not solely determine the system’s response to light. The minute absorption in the visible and the positive Soret coefficients for two solutions with Δn>0 but opposite responses (δn>0 and δn<0) should exclude photo-thermal and thermophoretic driving forces. The qualitative difference between the responses of the solutions in different solvents, points towards a microscopic origin of the light–matter interaction. Shedding light on the specificity of these materials might unlock the quest for other complex fluids which could present similar phenomena. Elucidation of the underlying mechanism will facilitate the control of macromolecular manipulation, the investigation of soft matter nonlinear optics and offer several perspectives utilizing the richness of the polymer science.

Biography:
George Fytas is professor of Physical Chemistry in the Department of Materials Science & Technology of the University of Crete, affiliated member of IESL/FORTH and External Member of the Max Planck Institute for Polymer Research in Mainz. George Fytas has received the BS in Chemistry Department of the University of Athens and the PhD with from the Technical University of Hannover in Germany. He performed his postdoc research in SUNY at Stony Brook in USA and received his habilitation from the University of Bielefeld in Germany. George Fytas trained 29 PhD students and 14 postdocs who all have successful carriers worldwide. He published over 250 peer reviewed scientific articles (Science, Nature (Materials,-Nanotechnology,-Chemistry), Nanoletters, Angewandte Chemie JACS, ACS Nano, Adv. Mater, PRL), one edited book and 10 reviews in books. His published work has received more than 7000 citations (HI: 42).
He has received a honor professorship offer from the University of Patras and the first FO.R.T.H Award for Basic Research (1999). He was nominated as external member of Max Planck Society (1998), received a Humboldt Senior Research Award (2002), became a Fellow of the American Physical Society (2004), received an invited professorship in the University of Lille (2009, 2012) and is Adjunct Professor at the University of Akron (2013). He served as Regional Editor of Colloid & Polymer Science and member of the Editorial Advisory Board in four international journals. His mission is the basic understanding and prediction of the behavior and tunability of unconventional physical properties of structured soft materials with spatiotemporal complexity.


Thursday, June 19, 2014
9:00 a.m.

Room 130
Polymer Engineering Academic Center

George Fytas
Max Planck Institute for Polymer Research, Germany
Department of Materials Science, University of Crete and IESL-FORTH, Greece

DOWNLOAD: Click here to download the full abstract flyer

"Hypersonic Phononic Soft Composite Materials"

Phononic crystals, the acoustic equivalents of the photonic crystals, are controlled by a larger number of material parameters 1, 2. The study of hypersonic phononic crystals (hPnC) imposes substantial demand on fabrication and characterization techniques. Colloid and polymer science offer methods to create novel materials that possess periodic variations of density and elastic properties at mesoscopic length scales commensurate with the wave length of hypersonic phonons and hence photons of the visible light. The key quantity is the dispersion ω(k) of high frequency (GHz) acoustic excitations with wave vector k which is measured by the noninvasive high resolution spontaneous Brillouin light scattering. Here, examples from fabricated structures that allow manipulation of phonon propagation will be highlighted.
In periodic structures of colloid based 3D-hPnC, ω(k) has revealed hypersonic phononic band gaps of different nature: Bragg gap for propagation near the edge of the first Brillouin zone due to destructive interference and hybridization gap due to the interaction of particle eigenmodes with the effective medium acoustic branch. Due to the vector nature of elastic wave propagation, 1D-hPnC (alternating layers of porous silica and PMMA) constitute model systems for fundamental studies allowing a full description of the ω(k). Under normal and oblique incidence the direction -dependent longitudinal and shear moduli are obtained at nanoscale, while the incorporation of defects (cavity and surface layers) holds a wealth of opportunities to engineer ω(k). Elastic wave propagation through hierarchically nanostructured matter can involve unprecedented mechanisms as observed in the dispersion diagram of the spider dragline silk.

Biography:
George Fytas is professor of Physical Chemistry in the Department of Materials Science & Technology of the University of Crete, affiliated member of IESL/FORTH and External Member of the Max Planck Institute for Polymer Research in Mainz. George Fytas has received the BS in Chemistry Department of the University of Athens and the PhD with from the Technical University of Hannover in Germany. He performed his postdoc research in SUNY at Stony Brook in USA and received his habilitation from the University of Bielefeld in Germany. George Fytas trained 29 PhD students and 14 postdocs who all have successful carriers worldwide. He published over 250 peer reviewed scientific articles (Science, Nature (Materials,-Nanotechnology,-Chemistry), Nanoletters, Angewandte Chemie JACS, ACS Nano, Adv. Mater, PRL), one edited book and 10 reviews in books. His published work has received more than 7000 citations (HI: 42).
He has received a honor professorship offer from the University of Patras and the first FO.R.T.H Award for Basic Research (1999). He was nominated as external member of Max Planck Society (1998), received a Humboldt Senior Research Award (2002), became a Fellow of the American Physical Society (2004), received an invited professorship in the University of Lille (2009, 2012) and is Adjunct Professor at the University of Akron (2013). He served as Regional Editor of Colloid & Polymer Science and member of the Editorial Advisory Board in four international journals. His mission is the basic understanding and prediction of the behavior and tunability of unconventional physical properties of structured soft materials with spatiotemporal complexity.


Wednesday, May 21, 2014
11:00 a.m.

Room 307
Polymer Engineering Academic Center

Dr. Klemen Bohinc
University of Ljubljana, Faculty of Electrical Engineering, Ljubljana, Slovenia

DOWNLOAD: Click here to download the full abstract flyer

"Bacterial Adhesion Management on Material Surfaces"

The bacterial adhesion can be controlled by different material surface characteristics like surface roughness, on which we concentrate in our study. Different glass surfaces were prepared by polishing the glass plates with different gradations. The corresponding surface roughness was controlled by atomic force microscope and profilometer. The rate of adhered bacteria on glass surfaces was determined with spectrophotometer and scanning electron microscopy. Our results showed that the rate of adhered bacteria increases with increasing surface roughness. The increased adhesion of bacteria on more rough surfaces is the interplay between the increasing effective surface and increasing number of defects on the surface. At the end of my talk I will present recent results on stainless steel material surfaces.

Biography:
Klemen Bohinc graduated in the field of Physics at the Faculty of Natural Sciences, University of Ljubljana. In 2001 he received his Ph.D. in Electrical Engineering from the Faculty of Electrical Engineering, University of Ljubljana and in 2012 Ph.D. in Physics from the Faculty of Natural sciences and Mathematics, University of Maribor. Currently he is an Assistant Professor at the Faculty of Health Sciences, University of Ljubljana where he teaches Biomechanics and Biophysics. His research interests are electrostatics and statistical physics of biological macromolecules and membranes as well as microbial adhesion to material surfaces and heavy metal monitoring in food.


Monday, May 19, 2014
3:30 p.m.

Goodyear Polymer Center, Room 130

Dr. Lora Angelova
Newton International Fellow, University of Cambridge

DOWNLOAD: Click here to download the full abstract flyer

"Soft Matter and Art - Creating and Understanding Heritage Conservation Materials"

The conservation and treatment of cultural heritage artworks – from old master paintings to contemporary plastic sculptures – requires extensive study of their material composition, stability, and history as well as an understanding of the effects such treatments have on each object. Conservators rely heavily on tried-and-true cleaning solutions (e.g. saliva, ammonia, organic solvents) and recently introduced gels and emulsions from the cosmetic and medical industries. My research aim has been to design versatile conservation treatment systems based on polymer gels which address the major requirements and concerns of conservators. The gels - composed of partially hydrolysed poly(vinyl acetate) and borax - are both of the optimal viscosity for controlled delivery of cleaning solvents and aqueous systems to the complex topography of heritage artworks, and elastic enough to allow for their complete removal after cleaning, limiting the risk of residues. With this talk, I will describe the variables which affect the working properties of these materials, focusing on rheology and 11B NMR spectroscopy, demonstrate how they are used in conservation, and introduce some of our recent work on the incorporation of nanoparticles into the gels for SERS applications.

Biography:
Lora Angelova is a Newton International Fellow at the University of Cambridge, working in the Melville Laboratory for Polymer Synthesis with Prof Oren Scherman. She obtained her PhD from Georgetown University under the joint mentorship of Prof Richard Weiss (an Akron local!) and Dr Barbara Berrie, Head of Scientific Research at the National Gallery of Art. She is, unfortunately, part of the Cleveland brain-drain, having obtained a BA from Case Western Reserve University in 2007. Working in the small field of ‘heritage conservation chemistry’, she collaborates with museums and conservation studios throughout the US and Europe on the design and implementation of polymer gel cleaning systems.


Monday, May 5, 2014
12:00 p.m.

Aggarwal Lecture Hall, Room 130
Polymer Engineering Academic Center

Dr. Parvaneh Mokarian-Tabari
University College Cork, Department of Chemistry, Tyndall National Institute, Cork, Ireland

DOWNLOAD: Click here to download the full abstract flyer

"An in-situ Study of Kinetics of Rapid Self- assembly in Block Copolymer Thin Films during "Solve- microwave" annealing"

Microwave annealing is an emerging technique for achieving ordered patterns of block copolymer films in substrates, although little detailed understanding of how microwave annealing promotes the microphase separation of the blocks exists. Here, we use controlled power microwave irradiation in the presence of a solvent tetrahydrofuran (THF), to achieve lateral microphase separation in high Χ lamellar forming poly(styrene-b-lactic acid) PS-b-PLA. A highly ordered line pattern was formed within seconds on a silicon substrate. In-situ temperature measurement of the silicon substrate coupled to condition changes during "solvo-microwave" annealing allowed understanding of the processes to be attained. Our results suggest that the substrate has little effect on the ordering process and is essentially microwave transparent but rather, it is direct heating of the polar THF molecules that causes microphase separation. It is postulated that the rapid interaction of THF with microwaves and the resultant temperature increase to 55 ºC within seconds causes an increase of the vapor pressure of the solvent from 19.8 kPa to 7ti kPa. This enriched vapor environment increases the plasticity of both PS and PLA chains and leads to the fast self-assembly kinetics. Comparing the patterns formed on silicon, germanium and silicon on insulator (SOI) and also an in-situ temperature measurement of silicon in the oven confirms the significance of the solvent over the role of substrate heating during "solvo-microwave" annealing. Besides the short annealing time which has technological importance, the coherence length is on a micron scale and dewetting is not observed after annealing. The etched pattern (PLA was removed by an Ar/O2 reactive ion etch) was transferred to the underlying silicon substrate fabricating sub-20 nm Si nanowires over large areas demonstrating that the morphology is consistent both across and through the film.

Biography:
Dr. Mokarian-Tabari is a Research Fellow at the University College Cork and the Centre for Research on Adaptive Nanostructures and Nanodevices (CRANN) and AMBER Centre, Trinity College Dublin, Dublin, Ireland. Dr. Mokarian-Tabari serves as a Conference Program Committee member for the 2014 SPIE Micro-and Nanotechnology Sensors, Systems and Applications Conference, VI.


Monday, May 12, 2014
2:00 p.m.

Aggarwal Lecture Hall, Room 130
Polymer Engineering Academic Center

Dr. S. Radhakrishnan, Director
Research Development & Innovation
Maharashtra Institute of Technology

"Conducting Polymers: Novel Structures and Applications"

The new conjugated polymers got a huge impetus after the award of Nobel Prize to the stalwarts of this field in 2002. Poly(aniline), Poly(pyrrole ) and Poly(thiophene) became the center of attention and there was a boom of publications related to these polymers. However, lack of process ability and solubility in common solvents restricted their manufacture and applications. In recent years, novel chemical routes have been adopted to overcome these limitations. The combination of conducting polymers with nanostructures together with other nano-materials has become a powerful technique for tailoring their properties for wide ranging applications. As of today, conducting polymers are again “in things” for many industries and a fertile field for innovation. The presentation describes the recent progress in this area along with Dr. S. Radhakrishnan’s contribution for synthesis of novel dendritic polyaniline, conducting polymer nanotubes, functionalized conducting polymers, band gap tuning etc. The recent applications of these conducting polymers to numerous areas such as chemical sensors, piezo-sensors actuators, electrochemical oxidation reactions and energy conversion/storage devices, smart coatings for corrosion protection, dye adsorption and impurity detection are also covered in the present lecture.

Biography:
Dr. S. Radhakrishnan received his Ph.D. in materials science from National Chemical Laboratory, (Pune University) in 1977. He was Post-doctoral fellow at Twente University, Netherlands and British council Visiting Scientist at Strathclyde University, Glasgow, UK. He has more than 30 years’ experience in R&D at National Laboratories of C.S.I.R., India. He was heading the R&D at a private chemical industry for 3.5 years. Currently he is Professor and Director Research Development & Innovation at Maharashtra Institute of Technology, Pune, India. He has more than 160 publications and 38 patents, 6 in USA and 2 in Europe. He has guided 16 Ph.D. students and 12 Masters level projects.

He was recipient of Materials Research Society (I) award in 2004 and Scientist of the Year award of NCL Research Foundation. He is Fellow and Vice President of Maharashtra Academy of Sciences, Fellow of Indian Plastics Institute, Fellow of SAEST, and Chairman Indian Plastics Institute and Founder council member of Asian Polymer Federation. His current interests are Specialty Polymers and their applications in Electronics, Energy conversion, Sensors and Medical devices Nano-Materials and Composites, Special Coatings and Green Technology.


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