Third Day Poster Session, 17 June 2010 - NanoTR-VI

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Poster Session, Thursday, June 17
Theme F686 - N1123
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Binary Memory Cells on the Base of Stimuli-Sensitive Macromolecules
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UIbragim SuleimenovUP P*, Grigoriy MunP Pand Ellina MunP
PAIPET – Almaty Institute of Power Engineering and Telecommunications, Baitursynova 126, Almaty 050013, Kazakhstan
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PChemical faculty of Kazakh National University, Karasai Batyra 95, 050012 Almaty, Kazakhstan
Abstract-It is shown that macromolecules of thermosensitive polymer with hysteresis properties may be synthesized. It was shown theoretically
and experimentally that systems with information recording density comparable to molecular can be produced on the base of such polymers.
At present time, an active search of systems providing for
data recording at molecular and submolecular level takes
place. Search in this direction is stimulated by well-known
fact: the most compact data recording is realized in biological
systems.
In the present work a base for elaboration of data recording
systems using synthetic macromolecules were laid. It is shown
that in solutions of stimuli-responsive polymers hysteresis
phenomena take place. The dependence of solution’s optical
density on temperature obtained under the solution heating
differs significantly from the analogous curve obtained under
its cooling. This is the basis for realization of digital units.
Poly-N-isopropylacrylamid (PNIPAM) aqueous solution
(MM= 135 000 with concentrations 0,2 weight % was
analyzed). The dependence of solution’s optical density under
heating and cooling in quasistationary regime with thermo
stating was registered. The example of results obtained is
shown at Figure 1. It can be seen that curves obtained differ
considerably from each other, besides, it is seen that there is a
temperature span which two different states of system can be
realized in.
1
0,8
0,6
0,4
0,2
D, rel. units
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0
31 32 33 34 35 36 37
Figure1. Temperature dependence of optical density of PNIPAM
aqueous solution from the temperature, obtained at increase (1) and
decrease (2) of temperature.
One of these states can be considered as logical zero, another
one-as logical one; conversion between them can be
considered as data recording. One should underline, that it is
not necessary for this conversion from one state to another to
affect system as a whole. This conclusion was demonstrated
by the example of cross-linked analogue of explored polymer,
i.e. gel (poly)N-isopropylacrylamide. It is known that such
network is thermosensitive, i.e. its degree of swelling in water
and water solutions depends significantly on temperature.
Firstly, it was experimentally shown that hysteresis
phenomena, i.e. difference between dependences of degree of
swelling on temperature obtained under the heating and
cooling of sample, takes place for gel of specified type too.
Secondly, it was found that conversion from one state to
another can pass locally under sample’s weak heating and
following temperature adjustment up to the value TR0
1
T,
0
PC
R(Figure2). Net parts corresponding to different states, which
can be put in accordance to logical zero and one, can exist
under the same thermodynamic variables (temperature,
pressure).
Therefore, hydrogel sample showing local hysteresis
phenomena can be considered as a medium suitable for data
recording. Dimensions of individual memory cell depend
significantly on the network’s elastic properties and are quite
big. However, they can be decreased at the expense of
conversion to individual macromolecules.
Figure 2. Temperature corresponds to two logical variables
Theory that confirm this conclusion for individual
macromolecules is developed in the work. This theory shows
that hysteresis phenomena of molecules of thermosensitive
polymer are caused by formation of intramolecular micelles.
The formation mechanism is completely analogous to that
passing in solutions of surfactants. The fact of existence of
hysteresis phenomena itself allows to conclude that under the
certain values of thermodynamic variables the fragments,
which form or not form micelles, can co-exist in the same
chain.
Correlation of this conclusion with behavior of hydrogel
microscopic sample shows that data recording can be realized
with high density. Dimensions of individual digital unit are
determined by dimensions of macromolecular chain fragments
capable to form micelle. At least, under the condition of weak
interaction between individual macromolecules in solutions
each of them can quite possess the properties of binary
memory cell.
We show, that complexes formed by such thermosensitive
macromolecules on the surface of solid body may be used as
an alternative data recording system. Possibility of using of
such complexes for creation of adapters capable to be a
connecting-link between classic solid-state circuit component
and systems of information processing on the quasibiological
basis is discussed.
* Correspondign author: Esenych@yandex.ru
6th Nanoscience and Nanotechnology Conference, zmir, 2010 683