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In this article, we decided to look at the upcoming breakthrough in the field of electronics - conductive plastics. In the future, conductive plastic will help bend large TVs into a regular roll.
Conductive plastic - the development of the future
Copper or silicon are mainly used in modern radio electronics. These materials are good semiconductors. If we talk about plastic, in most cases it simply covers the body of the product. Most people think so, but not scientists. They believe that organic carbon-based materials in the near future will be able to become the main raw material for the production of radioelements, magnets, and lasers.
Why does metal conduct current but wood does not?
The vast sea of electrons can carry charge. If you create a kind of “tilt”, that is, apply an electric field, then an electric current
— we are dealing with
metal
.
... Therefore, current
is not transmitted through such substances. These include plastics, wood, rubber, ceramics and many other substances.
Interesting materials:
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In which industries does static electricity occur?
Proper removal of static electricity from plastic is relevant for many industries:
- furniture manufacture;
- food industry;
- pharmaceuticals;
- production of plastic packaging and polymer films;
- printing;
- textile industry;
- production of foam materials;
- automotive industry;
- production of indoor and outdoor advertising;
- transportation.
All these cases are subject to the requirements of GOST, dedicated to the regulation of labor safety standards. There is also GOST R 53734.5.2.-2009, which is devoted to the issues of protection against electrostatic charge of electronic devices.
POM plastic for 3D printer
WHAT IS ACETAL (POM)?
Polyoxymethylene (POM), also called acetal and delrin, is well known for its use as an engineering plastic, for example in parts that move or require high precision.
ADDITIONAL INFORMATION
Acetal as a material sees common use as gears, bearings, camera focusing mechanisms and zippers.
POM performs exceptionally well in these types of applications due to its strength, rigidity, wear resistance and, most importantly, low friction. This last property is what makes POM such a great 3D printer filament.
For most of the 3D printer filament types on this list, there is a significant gap between what is made in the industry and what you can make at home with your 3D printer. For POM, this gap is somewhat smaller; The slippery nature of this material means that prints can be almost as functional as mass-produced parts.
When printing on POM 3D printer filament, be sure to use a hot print bed as the first layer doesn't always want to stick.
WHEN SHOULD I USE ACETAL 3D PRINTER FILAMENT (POM)?
Any moving parts that need to be low friction and rigid. We suggest that gear mechanisms in projects that use motors (e.g., radio-controlled cars) may be a suitable area for POM.
Coefficient of linear (thermal) expansion - from 10 to 15*10-5 /°C
Electrically conductive polymer: how scientists made metal from plastic
Every year, more and more gadgets are acquiring new talents, including the ability to connect with each other via the Internet. The concept of the “Internet of Things,” which emerged at the turn of the century, is becoming more clearly defined, but to fully utilize this idea, additional technical innovations are needed that can solve a number of problems, including those with charging wearable electronics. One of the most popular and futuristic solutions is to use human body heat. And for this we need lightweight, non-toxic, wearable and flexible thermoelectric generators. Scientists from Nagoya University (Nagoya, Japan) proposed using plastic. How is the electrical conductivity of plastic related to its structure, how to manipulate this parameter, and how effective is the use of plastic in creating thermoelectric generators? Answers to these questions await us in the scientists' report. Go.
Basis of the study
The human body can hardly be called a source of large amounts of heat.
However, in the wearable electronics aspect, the heat from our bodies can be used to keep our gadgets running. However, modern electrically conductive polymers cannot yet boast of their thermoelectric characteristics. To change this, you need to look inside the structure of the material and understand how everything works there. One of the key performance parameters in thermoelectric devices is the power factor: P
=
S
2σ, where
S
is
the Seebeck coefficient*
, and σ is the electrical conductivity.
The Seebeck coefficient*
(thermoelectric power) is a measure of the magnitude of the induced thermoelectric voltage in response to the temperature difference in a material caused by the Seebeck effect.Seebeck effect
- the phenomenon of the appearance of electromotive force at the ends of series-connected conductors, the contacts between which are at different temperatures.
Assuming that most conducting polymers other than poly(3,4-ethylenedioxythiophene) do not exhibit P
when doped with carriers.
This means that P
increases continuously with increasing σ for higher doping levels.
The justification for this non-standard behavior is the power relation* S
∝ σ−1/s, where
s
is equal to 3 or 4 (in most cases).
Power law*
- in statistics, this is a functional relationship between two quantities, when a change in one leads to a proportional change in the second quantity.
A similar effect occurs due to the disorder of polymer films, where charge transfer is affected by structural/energy disturbances within the film.
Recent studies have shown that control of the effects of randomness on the charge transfer process is a critical mechanism in achieving control of P
by modifying the empirical relation
S
-
σ
.
In this paper, the scientists show that the empirical S-σ ratio of a conducting polymer can indeed be changed through controlled doping of the carrier.
The main character of the experiments was the polymer PBTTT, or more broadly, poly[2,5-bis(3-alkylthiophen-2-yl)thieno(3,2-b)thiophene]. The choice of this particular polymer is not accidental, since it demonstrates the highest conductivity (S/cm, i.e. Siemens per centimeter) among semi-crystalline polymers, which is achieved through doping with 4-ethylbenzenesulfonic acid (C2H5C6H4SO3H).
Unlike conventional transistors that use a solid-state gate insulator, this technique allows the doping level of conductive polymers to be continuously controlled to very high concentrations through an electrochemical process. Thus, electrolytically controlled PBTTT allows a full consideration of the thermoelectric properties of PBTTT, including the metallic state.
Research results
First, the scientists studied the thermoelectric properties of PBTTT thin films doped with an electrolytic gate.
Image #1
Picture 1A
a diagram of the experimental setup is shown, which allows simultaneous measurement of
S
and σ during carrier doping.
Figure 1B
shows a snapshot of the structure of a
thin-film
) polymer PBTTT.
The carrier concentration can be continuously controlled by applying a gate voltage ( V
g) throughout the electrochemical doping process, where dopant ions penetrate into the bulk film.
σ is determined by the current-voltage characteristics obtained by using V
g (
1C
).
S is determined by the slope of the thermoelectromotive force (∆V )
as a function of the temperature difference (∆T
)
between the electrodes (
S
= ∆V
/
∆T
)
for each
Vg
(
1D
).
On 1E
shows the dependence of
σ
on
S
(top) and
σ
on
P
(bottom) obtained for two independent devices at room temperature.
Due to the constant doping of charge carriers, the data obtained from both devices had a fairly small scatter. And the observed form of the S
-
σ
is reversible if
V
g does not exceed the threshold for deterioration of the device.
The first thing that was noticed was that P
shows a clear maximum above 100 S/cm.
The appearance of a maximum P
is expected in the following two cases.
In the first case, these are ordinary non-degenerate semiconductors, where the ratio S
-
σ
is described by the logarithmic relation
S
∝ ln
σ
. However, the observed slope of the Jonker curve (the dependence of the Seebeck coefficient on the logarithm of conductivity) shows gradual changes around ~ 10 and 100 S/cm. This suggests that the usual thermally activated process cannot explain the experimental data obtained.
In the second case, it was noted that the maximum P
observed most often if the electronic state changes from non-degenerate to degenerate upon doping of the carrier.
In this case the S
-
σ
(or
P
-
σ
) ratio can be divided into two regions at the doping level that give the maximum value of
P
, which reflects a fundamental change in the electronic properties of the doped materials.
Ratio S
-
σ
(
1E
) follows the empirical
S
∝
σ
-1/4 (or
P
∝
σ
-1/2) in the region of low conductivity (
σ
< 100 S/cm), but with increasing σ the ratio
S
-
σ
moves away from this value, approaching
S
∝
σ
-1 (dashed line at
1E
).
Since the electrochemical doping process involves the penetration of dopant ions into the film, it is also necessary to investigate the possibility of structural modification of the molecular arrangement during the doping process, which may affect the thermoelectric properties. To do this, the scientists conducted x-ray diffraction (GIXD) experiments on the doped polymer, the results of which are shown in the image below.
Image #2
In untouched film ( V
g = 0 V), clear out-of-plane (h00) scattering peaks were observed, corresponding to a lamellar structure up to fourth order, as well as a peak in the (010) plane, corresponding to π-π stacking, indicating the highly crystalline nature of the PBTTT thin film.
Atomic force microscopy (AFM) of the film surface also confirmed high crystallinity. Upon carrier doping, the peak profiles show obvious changes ((100) peak at 2B
and
2D
; (010) peak at
2C
and
2E
).
Scattering vector qz
peak (100) continuously shifts to lower values until |
V
g|
increases due to the expansion of the distance between the plates from 23.3 Å at V
g = 0 V to 29.4 Å at
V
g = −1.6 V (
2D
).
This expansion is caused by the intercalation*
of bis(trifluoromethanesulfonyl)imide (TFSI) anions in the film
Intercalation*
is the reversible introduction of molecules, ions or atoms between molecules or groups (layers) of atoms of another type.
However, compared to previous studies, the increase in lattice pitch in this case is much larger (~6), which is close to the length of the TFSI anion (~8.0). This result implies that the TFSI molecules are arranged in an interlamellar position (between films) to form an end-to-end configuration with alkyl side chains ( 2F
).
Even with such a large grating expansion, no broadening of the diffraction peak lines was observed, i.e. The crystallinity of the lamellar structure is not degraded by anionic intercalation.
In addition, anionic intercalation occurs reversibly, as evidenced by the fact that the lattice spacing is restored close to the original value when a positive voltage is applied after doping.
qxy was also observed
peak (010) towards higher values upon doping, indicating a reduction in the π-π stacking distance (
2C
and
2E
).
In summary, the data from the experiments described above clearly indicate that the system does not exhibit structural degradation upon doping.
Next, ESR (electron paramagnetic resonance) spectroscopy was performed.
Image #3
At 3A
shows a TFT (thin film transistor) circuit with an ion-liquid gate, which allows simultaneous ESR and conductivity measurements when using
V
g.
Addition to 3C
In case of using negative V
g, a clear EPR signal of positive carriers (polarons) in the PBTTT chain is observed (
3B
).
The signal is observed with a g value of about 2.003 regardless of the Vg value, if an external magnetic field ( H
) perpendicular to the substrate is additionally used.
This result indicates that the carriers are located in the region with an edge-on
(i.e., edge) orientation (
3C
), which is consistent with the GIXD results showing the absence of crystalline destruction in the doped film.
From the integrated intensity of the EPR signal, it was also possible to determine the spin susceptibility (χ) of the doped film. On 3D
shows a graph of χ versus
σ
, obtained simultaneously with EPR measurements.
In the region of low conductivity, χ
was observed with increasing σ.
In lightly doped regions, where the polarons are magnetically isolated, the spin susceptibility follows Curie's law:
χ = Ng2µB2S(S+1) / 3kBT
, where
N
is the total number of spins.
In this case, the spin susceptibility is proportional to the carrier concentration n
, therefore, the relation χ ∝
σ
must be in a state of constant mobility.
This relationship is indeed observed in the region of very low conductivity σ
< 0.01 S/cm (
3D
), which indicates the dominance of isolated polarons in charge transfer.
If the value of σ exceeded 1 S/cm, then a clear broadening of the lines was observed ( 3E
), indicating a completely different spin dynamics in this region.
In such a situation, delocalization of carriers was observed. This indicates that energetic disorder does not dominate the transport process in a crystalline domain with σ
above 1 S/cm.
When delocalized carriers form a degenerate (or metallic) state after doping, Curie's law*
no longer holds, and is replaced by the Pauli spin susceptibility, where χ is proportional to the density of states at the Fermi energy level rather than the carrier concentration
n
.
Curie's law*
- the degree of magnetization of paramagnetic materials is inversely proportional to temperature in the case of temperature changes and a constant external field.
Almost complete saturation of the increase in χ was also observed in the case of an increase in σ
above 1 S/cm, which includes line broadening due to carrier delocalization. This confirms the formation of a degenerate (or metallic) electronic state in domains with edge orientation.
In the case of σ
~ 100 S/cm ESR signals did not show any anomalies, and the
S
-
σ
showed a deviation from
S
-
σ
-1/4 (
1E
). This suggests that thermoelectric properties change regardless of the microscopic electronic state in the domains.
Image #4
Schedule 4A
shows the temperature dependence
of σ
obtained at different values
of V
g.
At room temperature ( σ
RT) and increasing |
V
g|
an increase in conductivity was observed. At a sufficiently high value | V
g|
dσ
/
dT
appears , indicating a metallic state.
The metallic state was observed even at temperatures below 200 K and | V
g|
> 1.7 V, which is below the freezing temperature of the electrolyte. These observations were further confirmed by magnetoresistance measurements at V
g = −2.2 V and 150 K (
4B
).
Image #5
To conclude their work, the researchers analyzed the relationship between charge transfer and thermoelectric properties. On chart 5A
shows the
S
-
σ
at room temperature obtained both in this study and in other studies using other doping methods.
Scientists point out that the conductivity at which the ratio S
-
σ
deviates from the empirical value and agrees quite well with the conductivity at which charge transfer is observed in metals, i.e.
σ
RT ~ 100 S/cm.
This confirms that the ratio S
The ∝
σ
-1 observed in the high conductivity region does follow the Mott equation, reflecting the metallic nature of the system.
In contrast, σ exhibits a nonmetallic temperature dependence in the region of σ
RT <100 S/cm, although the microscopic electronic state in the crystalline domain is metallic above 1 S/cm. This result indicates that the macroscopic charge transfer process is mainly limited by structural heterogeneity such as domain boundaries rather than by charge trapping within crystallites.
The researchers recall that the macroscopic process of charge transfer in polycrystalline polymer films is modeled by linking molecules between crystalline domains ( 5B
). In this case, the local structure of the binding molecules significantly affects the charge transfer process.
In this case, the domain coupling should be quite sensitive to doping conditions, probably due to the structural/energetic disorder of the isolated bond molecules induced by the dopant. In other words, moderate doping using existing electrolyte gating techniques allows efficient interconnection of crystalline domains, resulting in a macroscopic metallic junction giving maximum power factor in the PBTTT thin film.
For a more detailed acquaintance with the nuances of the study, I recommend taking a look at the scientists’ report and additional materials to it.
Epilogue
An electrically conductive polymer is not something new, but in this work, scientists were able to improve it, thereby increasing its thermoelectric characteristics.
The bottom line is that thin films inside a polymer consist of crystalline and non-crystalline parts, which greatly complicates the process of studying the properties of polymers, let alone manipulating them. However, the polymer used in this study was PBTTT, which was embedded with a thin layer of ionic electrolyte gel to enhance conductivity. To successfully connect these two elements, it was necessary to apply a certain voltage, which also made it possible to evaluate the structural properties of the resulting system.
The resulting polymer, in terms of its conductive properties, was more like metal than plastic. However, this was only achievable under certain conditions (voltage and temperature). In the future, scientists intend to continue their work, concentrating on improving the method of converting polymers by possibly changing the method of forming the system (searching for an alternative to doping).
Thanks for reading, stay curious and have a great week guys.
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Cleaning. Plastic for cleaning 3D printer
WHAT IS CLEANING THREAD?
Unlike other filaments on this list, cleaning 3D printer filaments is not used to print objects, but to clean 3D printer extruders. Its purpose is to remove any material from the hot end that may have remained from previous prints. While this is a good general practice, using 3D printer filament cleaning is especially useful when transitioning between materials that have different temperatures or print colors.
ADDITIONAL INFORMATION
The general procedure involves manually feeding 3D printer cleaning filament into the heated print head to dislodge the old material, then slightly cooling the hot end and pulling the filament out again. For more detailed instructions, check the manufacturer's information for the specific thread you are using.
A few additional things to note:
- The "print" temperature depends on what types of 3D printer filament you've used previously, as well as the one you want to use later. (3D printer filament cleaning is stable between 150 and 280°C.)
- Usually there is no need to use more than 10 cm of thread at a time.
- There are other cleaning methods, including the popular "cold draw" technique, which is similar to the procedure above and does not require cleaning the 3D printer filament.
WHEN SHOULD I USE 3D PRINTER CLEANING FILAMENT?
You should consider cleaning your 3D printer filament between prints, using two materials with wildly different temperature requirements, or every now and then to give the hot end a little TLC.
Properties and Application
The scope of applications of conductive polymers is constantly expanding due to their easy processing. They have applications as antistatic materials and are used in commercial displays and batteries, but their use is limited by high manufacturing costs, inadequate material properties, toxicity, poor solubility, and inability to be used directly in the melt process. There is evidence in the literature that they are also promising in organic solar cells, organic light-emitting diodes, actuators, electrochromism, supercapacitors, biosensors, flexible transparent displays, electromagnetic shields, and possibly as a replacement for indium oxide. Conducting polymers are rapidly finding new applications as highly processable materials with better electrical and physical properties and lower costs. New nanostructured forms of conducting polymers with their large area and better dispersibility provide new ideas in nanotechnology.
Barriers to application
Conducting polymers have low solubility in organic solvents, which reduces their processability. In addition, the charged organic polymer chain is often unstable to atmospheric moisture. Compared to metals, organic conductors are expensive and require multi-step synthesis. Good processability for many polymers requires the introduction of soluble substituents, which can further complicate the synthesis process.
Story
Voltage Controlled Switch, Organic Polymer Electronic Device 1974 Smithsonian Chip Collection.
In 1950, it was discovered that polycyclic aromatic compounds form semiconducting halogen salts on a charge transfer complex. This finding indicated that organic compounds could conduct current. Organic conductors have been discussed periodically, and this area has received special attention from the scientific world due to the prediction of superconductivity resulting from the BCS theory.
Beginning in 1963, Bolto and co-workers reported conductivity in iodo-doped polypyrrole. This Australian group eventually achieved resistivities below 0.03 ohm cm for some conducting polymers, not far from modern values.
At this time, polymerization processes were not studied in detail. Modeling of conductivity mechanisms has also not yet been carried out; Neville Mott had yet to write works on conductivity in disordered structures. Later, de Surville and his co-workers reported the high conductivity of polyaniline. In 1980, Diaz and Logan reported polyaniline as a potential electrode material.
Much of the early work in polymer physics and chemistry was done with melanin, due to the proximity of this research to medical applications. For example, in the early 1960s, Blois and his colleagues discovered the semiconducting properties of melanin, and then they began to determine its physical structure and properties. Strictly speaking, all polyacetylenes, polypyrroles and polyanilines are melanins.
In 1974, McGuinness describes an "active organic polymer electronic device": a voltage-controlled binary switch. This device uses DOPA-melanin, a self-alloying copolymer of polyaniline, polypyrrole and polyacetylene. This work demonstrates the use of classical negative differential resistance.
In 1977, Alan Heeger, Alan McDiarmid and Hideki Shirakawa reported the high conductivity of oxidized iodinated polyacetylene. These researchers later published groundbreaking papers on the structure and mechanisms of conduction in organic conductors. For this research, they were awarded the Nobel Prize in Chemistry in 2000 “for the discovery and development of conducting polymers.”
> Notes > Links
- Electrically conductive polymers
- Magazine Polymer Materials
Implementation of technology
Relatively recently, a Japanese company pleased customers and released a unique TV. The main material used in manufacturing was conductive plastic. Plastic displays are quite thin. Their thickness is only 1 mm. Ideally, everyone will be able to roll such a screen or stick it on the wall instead of wallpaper. The cost is still high, but many experts argue that such displays could become common property within a few years. Another advantage is that such screens have good color reproduction, as well as fairly low power consumption.
Plastic flexible TV
At Ohio State University, experts have made magnets from organic material for the first time. In New Jersey, they were able to develop a new electric laser that worked on plastic. If a low-temperature regime is created for this material, it will be able to acquire the properties of a superconductor.
South Korean has embarked on the path of creating flexible integrated circuits. This is the beginning of a truly long journey to create full-fledged microcircuits, since at the moment the question of how to form organic and inorganic transistors on the same substrate is under development. In the near future, almost every reader will be able to create a newspaper with their own hands. It will be enough to simply attach a piece of paper to your cell phone or computer. Then all the necessary information can be downloaded from the Internet.
Introducing VOLTA, a conductive composite filament from FILAMENTARNO!
New material for 3D printing from the Filamentary team, as always, beyond competition! Let's tell you the story of the creation of this material.
Of course, before we even started production, we studied the offers on the market. Our surprise knew no bounds when, in trying to find a competitive product, we most often came across completely vague offers of some kind of conductive ABS without any accompanying information. It conducts current. Dot. And what resistance it has and other parameters were kept silent. With great difficulty, we found at least some data from literally one seller. Imported manufacturers fared a little better, both with the resistance of their conductive composites and with information about them.
Don’t let the abundance of numbers scare you, the main thing is highlighted. During the experiments, it turned out that quite a few factors influence the conductivity of the sample, so it was decided to present all the measurement figures so that everyone could draw their own conclusions and convert them into units of measurement convenient for them.
The test subjects were printouts from #VOLTA with reliable holes for bolts and a known volume and cross-section of the neck located between the holes. The calculations took into account only the cross-section and length of the neck from edge to edge of the washer.
Experiment No. 1 The length of the neck between the washers was 10 cm, its width was 8.5 mm, and its thickness was 5 mm. Neck cross section 8.5x5=42.5mm2 Resistance at room temperature was ~ 173 Ohms.
Experiment No. 2 The length of the neck between the washers was 5 cm, its width was 8.5 mm, and its thickness was 5 mm. Neck cross section 8.5x5=42.5mm2 Resistance at room temperature was ~ 71 Ohm.
Experiment No. 3 The length of the neck between the washers was 5 cm, its width was 8.5 mm, and its thickness was 2.5 mm. Neck cross-section 8.5x2.5=21.25mm2 Resistance at room temperature was ~ 115 Ohms.
Experiment No. 4 The length of the neck between the washers was 5 cm, its width was 8.5 mm, and its thickness was 7.5 mm. Neck cross section 8.5x7.5=63.75mm2 Resistance at room temperature was ~ 53 Ohms.
Based on what we were taught at school (some are better, some are worse...), the resistivity (p) is calculated as follows: p=R*S/l and the unit of measurement in the si system: Ohm*m
In experiment No. 3, the cross-sectional area of the sample neck was (S) 21.25 mm2 and the resistance ® 115 Ohm. The measured resistivity of the material: p = 115 Ohm x 21.25-6m2 / 0.05 m = ~0.05 Ohm*m In experiment No. 2, the cross-sectional area of the neck sample was 43 mm2 and the resistance was 71 Ohm. The measured resistivity of the material: p=71 Ohm x 43-6m2 / 0.05m = ~0.06 Ohm*m. In experiment No. 4, the cross-sectional area of the sample neck was 63.75 mm2 and the resistance was 53 Ohm. The measured resistivity of the material : p=53 Ohm x 63.7-6m2 x/0.05m =~ 0.07 Ohm*m
We will consider the average result to be 0.06 Ohm*m
No more boring numbers! Now you can start lighting the lights! Of course, here you won’t be able to do without numbers; those who wish can view them on the screen of a multimeter.
For starters, the voltage drop. Not noticed.
Current 30mA
Current 110mA
Current 150mA The lights are on, and very well!
