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J. C. lub. ournal. Presentation Series. Mehmet Kanık. http://bg.bilkent.edu.tr. Role of the responsive polymers. Optical Signals Electrical Signals Thermal Signals Mechanical Signals. Responsive Polymer Materials. Chemical Signals Biochemical Signals Others. or. Responsive
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J C lub ournal Presentation Series Mehmet Kanık http://bg.bilkent.edu.tr
Role of the responsive polymers Optical Signals Electrical Signals Thermal Signals Mechanical Signals Responsive Polymer Materials Chemical Signals Biochemical Signals Others or Responsive Polymer Materials (RPM) can adapt to environments regulate transport of ions and molecules change wettability and adhesion
Definition of JC Journal club From Wikipedia, the free encyclopedia A journal club is a group of individuals who meet regularly to critically evaluate recent articles in scientific literature. Journal clubs are usually organized around a defined subject in basic or applied research. For example, the application of evidence-based medicine to some area of medical practice can be facilitated by a journal club. Typically, each participant can voice their view relating to several questions such as the appropriateness of the research design, the statistics employed, the appropriateness of the controls that were used, etc. There might be an attempt to synthesize together the results of several papers, even if some of these results might first appear to contradict each other. Even if the results of the study are seen as valid, there might be a discussion of how useful the results are and if these results might lead to new research or to new applications. Journal clubs are sometimes used in the education of graduate or professional students. These help make the student become more familiar with the advanced literature in their new field of study. In addition, these journal clubs help improve the students' skills of understanding and debating current topics of active interest in their field. This type of journal club may sometimes be taken for credit. Research laboratories may also organize journal clubs for all researchers in the lab to help them keep up with the literature produced by others who work in their field.
Reconstructable surface and applications Change in their wettability, permeability, as well as adhesive, adsorptive, mechanical and optical properties. Reaction Stimuli RPM *In this area Ozan Aktaş and Mehmet Kanik will give a presentations in coming JC. Meetings..
Reconstructable surface fall into several categories • Considered Factors for Classification of Reconstructable Surfaces • Dynamics ( rate of responce). • Amplitude of changes of the material’s properties. • Reversibility of changes. • Intensity of the external signal that could trigger the changes.
Bulk reconstructable surfaces v.s. Thin films fall into several categories
RPM Brushes Entropic repulsion : Entrophy : In physics, an entropic force acting in a system is a macroscopic force whose properties are primarily determined not by the character of a particular underlying microscopic force (such as electromagnetism), but by the whole system's statistical tendency to increase its entropy. • Recommended reads about entropy • http://en.wikipedia.org/wiki/Entropic_force • http://en.wikibooks.org/wiki/Entropy_for_beginners • http://en.wikipedia.org/wiki/Entropy • Stochastic Processes and their Applications • Volume 117, Issue 1, January 2007, Pages 23-34 • The effect of an external field on an interface, entropic repulsion • Journal of Statistical Physics Volume 46, Numbers 1-2 / January, 1987
Chemical Grafting • Recommended reads about chemical grafting • http://www.freepatentsonline.com/4795801.pdf • http://dynamicdevelopment.com/chemgraf.html • http://www.freepatentsonline.com/6756419.pdf • Simon Q. Lud, Chemical Grafting of Biphenyl Self-Assembled Monolayers on Ultrananocrystalline Diamond, J. Am. Chem. Soc., 2006, 128 (51), pp 16884–16891 • R. Anbarasan, T. Vasudevan and A. Gopalan,Chemical grafting of poly(aniline) and poly(o-toluidine) onto PET fibre — a comparative study, European Polymer JournalVolume 36, Issue 8, 1 August 2000, Pages 1725-1733
RPM Brushes Two approachs, “grafted to” and “grafted from”, are presented for fabrication of adaptive and responsive interfaces. In this way you can produce films on planer and curved surfaces. Single Component Homo-Polymer Brushes • Responsive behaviour originated from : • Grafted polymer chains • Grafting densities. Why? Various environments used to trigger to reconstruction and change in the brush properties. If T > Tc in solution then “phase chage” Else no “phase change”. If “phase change” happens Then solvent quality and temperature changes. Temperature chage ionic strenght and pH in zwitterionic process and that changes; weting behaviour. These chages are reversible.
Phase Chage PHASE- any particular portion of a system, which is physically homogeneous, has a specific composition, and can be mechanically removed or separated from any other phase in the system. EQUILIBRIUM - The condition of minimum energy for the system such that the state of a reaction will not change with time provided that pressure and temperature are kept constant. XRD used to determine the phase and for thin films grazing incidence x-ray scattering (GIXS) measurements.
Phase Segregation Segregation in Materials refers to the enrichment of a material constituent at a free surface or an internal interface of a material. Recommanded reads about phase transition and segregation: • http://www.brocku.ca/earthsciences/people/gfinn/petrology/phase.htm • http://en.wikipedia.org/wiki/Segregation_in_materials • 3. Models of phase segregation and diffusion ofatomic species on a lattice, • Ricerche di Matematica 55: 105–118 (2006) • 4. Phase segregation in polymer thin films: Elucidations by X-ray and scanning force • microscopy Europhys. Lett, 45 (4), pp. 526-532 (1999). • 5. L. Sardone et al./Phase Segregation in Conjugated Polyrotaxane–Poly(ethylene oxide) • Blends Adv. Funct. Mater. 2007, 17, 927–932. • 6. Nanoscale Structural Engineering via Phase Segregation: Au−Ge System, • Nano Letter, January 5, 2010.
RPM Brushes Block Copolymer Block copolymers are composed of long sequences ("blocks") of the same monomer unit, covalently bound to sequences of unlike type. The blocks can be connected in a variety of ways; schematics of AB diblock and ABA triblock structures are shown below. Recommanded reads about block copolymer : http://www.princeton.edu/~polymer/block.html
RPM Nanostructured Netwok Films Nanostructured Network Films (NNF)s; that isi gel films and in many cases hydrogel films. Advantages : Fast kinetics of swelling and shrinking compared to bulk gels.
RPM Porous Thin Gel Films In porous bulk materials pore sizes increase by swelling, in thin films this is opposite. Applications : It can be used for regulation of transport, controlling diffusion range.
RPM Electrostatic Layer by Layer Assembilies It is known as nanostructured, organized, organic and hybrid thin films. Cloumb Interaction in a Material When considering ionic materials, the Coulomb interaction is by far the dominant term and can represent, typically, up to 90% of the total energy. Despite having the simplist form, just being given by Coulomb's law; it is in fact the most complicated to evaluate for periodic systems (subsequently atomic units will be employed and the factor ofill be omitted). This is because the Coulomb energy is given by a conditionally convergent series, i.e. the Coulomb energy is ill-defined for an infinite 3-D material unless certain additional conditions are specified. The reason for this can be readily understood - the interaction between ions decays as the inverse power of , but the number of interacting ions increases with the surface area of a sphere, which is given by Recommended reads about Cloumb Interaction: https://www.ivec.org/gulp/help/gulp_30_manual/gulpnode6.html
Smart and Self Healing Coatings “The structure of the coatings can be programed in the formulation.” External Stimuli Smart Surface Phase seperation of ingradients – “self-assemble” <<Programable Material>> Adaptation and Self Healing
Biointerfaces and Bioseperation RPM reveals adaptation in accordance with changes in living cells. Switching Adhesion between stimuli responsive Materials Proteins Cells Control of cell, proteins and adhesion for tissue engineering, bioseperation, modulation and regulation of biomolecule activity.
PNIPAAM Poly(N-isopropyl acrylamide) (pNIPAM or pNIPAAm) is a thermoresponsive or "smart" polymer. This polymer has a lower critical solution temperature (LCST) of ~31ºC in an aqueous environment. Below this LCST, the polymer chains are well hydrated and have a random coil configuration Above the LCST, the polymer chains take on a much more compact configuration by sudden dehydration and increased hydrophobic interactions. • When grafted onto a solid surface this phase change can be controlled by applying an external stimulus (temperature). Above the transition temperature (i.e., physiological temperatures), the grafted polymer chains collapse, and the surface becomes relatively hydrophobic and protein-retentive. In addition, when pNIPAM surfaces are used for cell culture, biological cells (prokaryotic and eukaryotic) will adhere and proliferate. In contrast, below the phase transition (e.g. room temperature), a pNIPAM grafted surface becomes relatively hydrophilic and non-fouling to protein adsorption. Furthermore, cultured biological cells will release from the substrate without the need for harsh cell removal methods. • These pNIPAM-grafted surfaces offer a number of possible novel applications including cell patterning[1], controlled drug release[2], cell sheet detachment and tissue engineering[3, 4]. There are a variety of methods for modifying a surface with NIPAM including co-grafting with other polymers, polymerizing pNIPAM on to reactive surfaces, and deposition of plasma polymerized NIPAM (ppNIPAM). • Recommended reads about PNIPAAM : • https://www.ivec.org/gulp/help/gulp_30_manual/gulpnode6.html • http://www.uni-muenster.de/Physik.PI/Fuchs/bio_nano_interface/bio_nano_interface.html
Micro and Nanoactuation External Stimuli Temperature, pH Change, Electric Micro-nanostructured RPM Swelling – deswelling, wetting-dewetting, adsorption-desorption
Information Next Presentation • From two to three dimensions : responsive particles • Challenges for modelling stimulation and theory Thank You!
