Mehmet Kanik

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Mehmet Kanik
http//bg.bilkent.edu.tr
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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
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Applications of RPM
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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.
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Adaptive sensors in nature
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Galaxy of RPM
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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 Aktas and Mehmet Kanik will
give a presentations in coming JC. Meetings..
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Reconstructable surface fall into several
categories

• Considered Factors for Classification of
  Reconstructable Surfaces
• Dynamics ( rate of responce).
• Amplitude of changes of the materials
  properties.
• Reversibility of changes.
• Intensity of the external signal that could
  trigger the changes.

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Bulk reconstructable surfaces v.s. Thin films
fall into several categories
Bulk Thin Film
Responce Long ( Minutes of tens to hours). Short(Seconds to hours).
Mechanism Migrate of macromolecules from bulk to surface or rearanging locally and decrease interfacial tension. Without volume repulsion and adoption a whole stretch, combination of a strong entropic repulsion polymer chains and crawded monolayers, phase segregation and phase change.
Duration of the responce Bad Good
Corruption of mechanical properties Yes No
Reversibility Weak Strong
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RPM Brushes
Entrophy
Entropic repulsion
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

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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
  1688416891
• 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

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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 gt 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.
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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.
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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/pe
  trology/phase.htm
• http//en.wikipedia.org/wiki/Segregation_in_materi
  als
• 3. Models of phase segregation and diffusion of
  atomic species on a lattice,
• Ricerche di Matematica 55 105118 (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 PolyrotaxanePoly(ethylene oxide)
• Blends Adv. Funct. Mater. 2007, 17, 927932.
• 6. Nanoscale Structural Engineering via Phase
  Segregation Au-Ge System,
• Nano Letter, January 5, 2010.

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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
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RPM Brushes
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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.
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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.
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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 of ill
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_3
0_manual/gulpnode6.html
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RPM Electrostatic Layer by Layer Assembilies
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Summery
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Emerging Application of RPMs
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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 ltltProgramable Materialgtgt
Adaptation and Self Healing
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Smart and Self Healing Coatings
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Smart and Self Healing Coatings
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Smart and Self Healing Coatings
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Smart and Self Healing Coatings
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Smart and Self Healing Coatings
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Smart and Self Healing Coatings
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Smart and Self Healing Coatings
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Smart and Self Healing Coatings
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Smart and Self Healing Coatings
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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.
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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
  patterning1, controlled drug release2, cell
  sheet detachment and tissue engineering3, 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/gulp
  node6.html
• http//www.uni-muenster.de/Physik.PI/Fuchs/bio_nan
  o_interface/bio_nano_interface.html

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Micro and Nanoactuation
External Stimuli Temperature, pH Change, Electric
Micro-nanostructured RPM
Swelling deswelling, wetting-dewetting, adsorpti
on-desorption
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Sensors
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Sensors
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Sensors
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Sensors
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Information Next Presentation

• From two to three dimensions responsive
  particles
• Challenges for modelling stimulation and theory

Thank You!