6. From Harvard University Digital Library
for Physics and Astronomy
• Improved photovoltaic cells and electrodes
for use therein, particularly electrodes
employing amorphous silicon or
polyacetylene coating are produced by a
process which includes ……..
http://adsabs.harvard.edu/abs/1983doe..reptV....S
7. From Harvard University Digital
Library for Physics and Astronomy
• Planar and sandwich types of
polyacetylene metal-semiconductor field-
effect transistors (MESFETs) have been
fabricated.
http://nina.ecse.rpi.edu/2dfet/images/ntype2_big.gif
http://adsabs.harvard.edu/abs/1991JaJAP..30.2101C
8. Chemical Sensor
• Polyacetylene based nonlinear optical
material prepared by ring-opening
metathesis polymerization of
cyclooctatetrene derivatives.
15. Special properties
• per-chain stiffness close to diamond
• high coefficients for tripling the frequency
of incoming light
• negative thermal expansion coefficients
tunable to near zero by introducing
defects
16. Most Application
• printed inks containing diacetylene
microcrystals have been used as time-
temperature indicators
17. Mechanism
• Diacetylenes typically have an actuation
energy for thermal polymerization of about
20 to 28 kcal/mol, which can be tuned to
closely match the activation energy and
degradation rate for important perishables
18. Good color indicator
• Color changes of the diacetylene
microcrystals during thermal
polymerization provide a visual indication
of whether a perishable product in the
same thermal environment has degraded
as a result of integrated time-temperature
exposure
19. • Over a billion of these diacetylene
polymerization-based indicators have
been used on individual vaccine vials
since 1996 to assist disease eradication in
parts of the world that do not have a
reliable cold chain
20. • The United States Army is using these
diacetylene indicators on cartons of their
MREs (Meals Ready to Eat)
21. Explosive compound
• Though the advantages mention before,
there is a problem on synthesis
Polydiacetylenes
• With increasing n, crystals comprising only
polyynes--that is, R − (C ≡ C) n − R molecules--
become increasingly unstable, unless R is a
bulky substituent group
22. Dangerous…..
• At room temperature, it can explode if
subjected to physical shock, and it
decomposes slowly under ambient light,
forming an insoluble material with a
graphite-like appearance
24. Why is it?
• The abundance of transition metal–catalyzed
reactions available for adding substituents in
place of a carbon-halogen bond makes PIDA
a potential precursor to a wide variety of
polydiacetylenes.
• Sn2 Sn1
− δ−
Nu + C X C Nu + X− δ+ δ−
+
δ C X C + X−
−
C + Nu C Nu
Organic Chemistry Bruice
25. A complex compound
• C4I2 is complexed with a specially chosen
agent, an oxalamide. In these crystals,
1,4-addition polymerization of diacetylene
occurs spontaneously to produce single
crystals of the complexed polydiacetylene
26. Getting Better
• The complexing agent appears to stabilize
the polymerized C4I2 against explosive
decomposition and eliminates the type of
disorder
27. Disorder comes from nature
• Disordered along the direction of the
molecular axis. In these crystals, the
alignment between adjacent monomers is
random, preventing ordered
polymerization
28. Problem caused from disorder
• Obtaining the desired optical and
electronic properties of a given conjugated
polymer requires a highly ordered
molecular structure
29. Way to solve the problem
• if the diynes are first aligned appropriately
in the solid state at a distance
commensurate with the repeat distance in
the target polymer, then their arrangement
in space will control their reactivity, leading
to ordered topochemical polymerization
30. Best distance
• Distance of 4.9A is highly preferable for
the aligned dynes with target to form
highly order structure.
31. Conclusion
• With all the efforts to make the
polydiethylene mentioned before, we shall
have a blueprint on how could these
material be utilized and how to make it
real.
32. • Whether or not linear carbon synthesis is
practical by the poly(C4I2) route, the idea
with using poly C4I2 has provided both an
exciting new electronic material and a
route that could lead to novel related and
derivative materials.
33. References
• Dangerously Seeking Linear Carbon Ray H. Baughman Science
mag Vol. 312. no. 5776, pp. 1009 - 1110
• Preparation of Poly(diiododiacetylene), an Ordered Conjugated
Polymer of Carbon and Iodine Aiwu Sun, Joseph W. Lauher,
Nancy S. Goroff Vol. 312. no. 5776, pp. 1030 - 1034
• Harvard University Digital Library for Physics and Astronomy
• Organic Chemistry ver 4 Bruice
Original Image Source:
( Images used in this PowerPoint are modified by Stan Yang)
http://stc-mditr.org/research/oeoaomd/projects/2.2.1.cfm
http://nina.ecse.rpi.edu/2dfet/images/ntype2_big.gif
