In the human body, full of biological non-Newtonian fluids exist. For example, synovial fluids exist in our joints,
which contain full of biopolymers, such as hyaluronan and mucin. It is thought that these polymers play critical roles on
the smooth motion of the joint. Indeed, luck of biopolymers in synovial fluid cause joint pain. Here we study the effects
of polymer in thin liquid layer by using an original experimental method called Film Interference Flow Imaging (FIFI). A
vertically flowing soap film containing polymers is made as two-dimensional flow to observe turbulence. The thickness
of water layer is about 4 μm sandwiched between surfactant mono-layers. The interference pattern of the soap film is
linearly related to the flow velocity in the water layer through the change in the thickness of the film. Thus the flow
velocity is possibly analyzed by the single image analysis of the interference pattern, that is, FIFI. The grid turbulence
was made in the flowing soap films containing the long flexible polymer polyethyleneoxide (PEO, Mw=3.5x106), and
rigid polymer hydroxypropyl cellulose (HPC, Mw > 1.0 x106). The decaying process of the turbulence is affected by PEO
and HPC at several concentrations. The effects of PEO are sharply seen even at low concentrations, while the effects of
HPC are gradually occurred at much higher concentration compared to the PEO. It is assumed that such a difference
between PEO and HPC is due to the polymer stretching or polymer orientation under turbulence, which is observed and
analyzed by FIFI. We believe the FIFI will be applied in the future to examine biological fluids such as synovial fluids
quickly and quantitatively.
Novel high-strength gels, named double network gels (DN gels), show a smart response to altering external
electric field. It was reported that a plate shape of the DN gel bends toward a positive electrode direction when a static
(DC) electric field is applied. Based on this previous result, it has been tried to develop a novel soft and wet actuator,
which will be used as an automatically bulging button for cellar phones, or similar small devices. First, a bending
experiment of a hung plate-shape DN gel was done, and its electric field response was confirmed. Second, the response
of a lying plate-shape DN gels was confirmed in order to check the bulging phenomena. The edge of three plate-shape
gels that was arranged radially on a plane surface was lifted 2mm by applying DC 8V. This system is a first step to make
a gels button. However the critical problem is that electrolysis occurs simultaneously under electric field. Then, the water
sweep out from gels, and gels is shrinking; They cause the separation between aluminum foil working as electrode and
gels. That is why, a flexible electrode should be made by gels completely attached to the gels. As a third step, a push
button is tried to make by a shape memory gels (SMG). The Young's modulus of the SMG is dramatically changed by
temperature. This change in the modulus is applied to control the input-acceptable state and input-not-acceptable states
of the button. A novel push button is proposed as a trial, and its user-friendliness is checked by changing the size of the
button. The button is deformed by pushing and is back to original shape due to the property of shape memory. We
believe the mechanism of this button will be applied to develop new devices especially for visually impaired persons.
Sensitive deformation of polymer gel actuator induced by various stimuli has been intensively investigated. The
utilization of light however will significantly broaden their applications. Here we show that photo-responsive gels
prepared from rigid poly(amide acid) chains having azobenzene moieties in main chains can undergo a macroscopic
deformation induced by photo-isomerization. A rod-shape gel can sharply and swiftly bend by blue laser irradiation and
reversibly straighten when exposed to visible light. By using a scanning microscopic light scattering, the optimal
preparing condition of the gels was determined and the reversible change in mesh-size between 2.1 nm and 0.83 nm was
observed.
Medical treatment for injuries should be easy and quick in many accidents. Plasters or bandages are frequently
used to wrap and fix injured parts. If plasters or bandages have additional smart functions, such as cooling, removability
and repeatability, they will be much more useful and effective. Here we propose innovative biocompatible materials, that
is, nontoxic high-strength shape-memory gels as novel smart medical materials. These smart gels were prepared from
two monomers (DMAAm and SA), a polymer (HPC), and an inter-crosslinking agent (Karenz-MOI). In the synthesis of
the gels, 1) a shape-memory copolymer network is made from the DMAAm and the SA, and 2) the copolymer and the
HPC are crosslinked by the Karenz-MOI. Thus the crosslinking points are connected only between the different
polymers. This is our original technique of developing a new network structure of gels, named Inter-Crosslinking
Network (ICN). The ICN gels achieve high ductility, going up to 700% strain in tensile tests, while the ICN gels contain
about 44% water. Moreover the SA has temperature dependence due to its crystallization properties; thus the ICN gels
obtain shape memory properties and are named ICN-SMG. While the Young's modulus of the ICN-SMG is large below
their crystallization temperature and the gels behave like plastic materials, the modulus becomes smaller above the
temperature and the gels turn back to their original shape.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.