CS255341B1 - The method of homogeneous doping of polyacetylene powder by iodine vapor and apparatus for this process - Google Patents

Abstract

The solution relates to a method and a device for homogeneously doping powdered polyacetylene with iodine vapor. The essence of the method lies in the fact that polyacetylene grains are treated in a closed system with iodine molecules in the vapor phase at laboratory temperature and an initial pressure of 10"3 Pa of a protective nitrogen atmosphere. The said device consists of a container of powdered polyacetylene, equipped with a sealing nitrogen inlet and a container of crystalline iodine, equipped with a sealing nitrogen outlet, the containers being firmly connected by a tube containing a pulp partition and both containers and the tube having a common horizontal axis and the entire connected structure is mounted in this axis at one end in a bearing and at the other end firmly connected by a coupling to the shaft of an electric motor.

Description

The invention relates to a method and apparatus for doping polyacetylene powder with iodine vapors.

Polyacetylene has a simple chemical structure and small amounts of various impurities, whether acceptors or donors, drastically alter its electrical, magnetic, optical and thermal properties. Achieving optimal physical parameters of polyacetylene therefore depends on the doping method. The doping method is in close association with the doping device, so that each doping method corresponds to a suitable doping device.

In general, the distribution of impurities in the polyacetylene structure may be homogeneous and heterogeneous. Reproductive physical properties can only be achieved by the bomogenic distribution of the impurities between the polyacetylene fibers. The admixture may react with polyacetylene in the gas, solution, melt and solid state. Great attention is paid to equipment and method of doping polyacetylene with gas phase impurities. Gas phase doping may occur if the gas additive is composed of neutral molecules and its saturated vapor pressure is high enough for the reaction to proceed. A frequently used additive for doping polyacetylene is iodine gas.

Polyacetylene can be synthesized in the form of a film and a powder. All prior art polyacetylene doping devices and methods have been developed for polyacetylene film. American authors Park, Heeger, Fray, and MacDiarmid doped polyacetylene in the form of a film by exposing it to a stream of dry iodine-containing nitrogen. The doping rate was controlled by the iodine vapor pressure in nitrogen and the nitrogen flow rate. Haberkorn used a method of rapidly doping polyacetylene with iodine without an inert atmosphere at 40 ° C. 45-70% by weight of polyacetylene was reacted within 2 hours. iodine. Diets doped the polyacetylene param iodine films at 10 Pa and determined the amount of iodine trapped by weighing the samples at repeated intervals until the desired weight of the polyacetylene sample corresponding to the given doping degree was reached. All of the polyacetylene doping devices and methods described herein are suitable for doping polyacetylene films, but are not suitable for powder form. The powder form of polyacetylene, due to the large grain area and its random distribution, requires specific doping conditions.

This disadvantage is substantially eliminated by the process of doping polyacetylene according to the invention, which consists in treating the polyacetylene grains in a closed system with vapor phase iodine molecules at room temperature and an initial pressure of 10 ^-3 Pa of nitrogen atmosphere.

SUMMARY OF THE INVENTION The device according to the invention consists of a powdered polyacetylene powder container equipped with a sealable nitrogen supply and a crystalline iodine container fitted with a sealable nitrogen outlet, wherein the containers are firmly interconnected by a tube containing a cellulose baffle and both containers and tube share a horizontal and the entire shape in this axis is supported at one end in the bearing and at the other end firmly connected by the coupling to the motor shaft.

The diagram of the device is shown in the attached drawing. Powdered polyacetylene is poured into the polyacetylene container 1 and nitrogen is injected through the inlet 2 to form the protective atmosphere of the polyacetylene. To tray .1. the connected tube 3 is tapered in two places. There is a cellulose barrier in the narrowed area. The tube 3 is connected in a narrowed position to a spherical shaped container serving as a reservoir 4 of crystalline iodine. The cell barrier prevents polyacetylene powder from mixing with crystalline iodine and at the same time resists the rapid penetration of the iodine vapor into the space with polyacetylene. The iodine reservoir 4 is terminated with a drain 5 through which the flowing nitrogen escapes in the preparatory phases and the lateral serves as an input for the vacuum system. The whole device is fixed in the horizontal position in the holder 6, and the coupling 7. The holder 6 forms only a support in which the device can rotate freely. The clutch 7 firmly connects the device to a low speed electric motor.

The method of doping polyacetylene with iodine using the described apparatus is as follows:

The device shown in the figure is deprived of oxygen several times by repeated flushing with nitrogen gas followed by evacuation, the nitrogen stream being blown through inlet 2 and exiting through outlet 5. Through inlet 2 powder polyacetylene powder is poured into the container 1 without air. A predetermined amount of poison is placed in the container 4. A vacuum system is connected to the outlet 5 and the supply 2 is sealed. When the cvakuácie at 10 ^_3 mbar is sealed and the exhaust support 5. High vacuum sublimation of iodine, after passing through a baffle linked cellulosic fluff, powder polyacetylenes. The device thus prepared is placed in the holder 6 and the clutch 7 and is rotated around the horizontal axis by a slow electric motor.

As the device rotates, the grains of polyacetylene are kept in constant motion, with the probability of exposing all of the grain surfaces to iodine. The doping process takes place at room temperature and is complete after sublimation of all iodine.

The doping process can also be used for doping polyacetylene in the form of a film, polyvinyl chloride powder and other powdered polymers.

Example 1

Polyacetylene (PA) powder was synthesized by the Sigmund method (AO 181 984) and thermally isomerized at 180 ° C to the trans form. Crystalline iodine was purified by two-step sublimation. The bound amount of polyacetylene of mass m (PA) is equal to 2.55 g corresponding to the substance of the —CH— groups.

n (iCH) = ^{= 2 '55/13} = °' ^{196 moles 1} ) ·

This amount of polyacetylene was placed in the reservoir 1 of the pre-depleted oxygen-doping device, the dry nitrogen stream entering the inlet 2 and escaping the outlet 5 creating a protective atmosphere throughout the preparation phase.

In determining the necessary iodine mass, we proceeded from the requirement that for a weakly doped polyacetylene the molar fraction of iodine y - = 0.003. The weight of iodine required to achieve the above degree of doping was calculated based on the formula:

m (I) i) (1J. Μ (I | Μ (IJ ----) After weighing the necessary weight, the iodine was placed in container 4, the nitrogen inlet 2 was sealed and the Π outlet was connected to the vacuum system. (1 Pa su disconnected the vacuum system and outlet 5 was sealed. The device mounted in bracket B and clutch 7 was rotated by the electric motor at 10 rpm. Dosing was continued for two days. The amount of bound iodine was checked by reweighing the polyacetylene sample. .

Example 2

By the same procedure as in Example 1 hol

127

0,003 l

0196

0.003 = 0.075 g (II), using medium-doped polyacetylene. For the desired molar fraction of iodine y 0.05 and for the weight of polyacetylene m (PA) ----- 2.35 g • using the formula (I) and (II) calculated iodine mass:

The process of doping at room temperature was completed after four days.

Claims (2)

Example 1 Powdered polyacetylene (PA) was synthesized by Sigismund method (AO 181 984) and thermally isomerized at 180 ° C to form the trans form. Crystalline iodine is pure-grade sublimation. The amount of polyacetylene bonded by weight m (PA) is equal to 2.55 g of the reactive substance of the CH-groups. n (iCH) = 2'55 / 13 = 196196 mol í1) · This amount of polyacetylene was placed in the oxygen reservoir J of the doping device, whereby the dry nitrogen flowing through the outlet 2a from the outlet 5 formed the protective phase of the protective atmosphere. In order to determine the iodine mass required, the requirement for a low-melting polyacetylene to be a molar fraction of iodine was 0.003. The iodine mass required to gain the above-mentioned degree of doping, calculated on the basis of the relation: m (I) i) (IJ. Μ (I | M (I) -----) After weighing the required iodine mass, iodine placed in reservoir 4, 2 nitrogen feed was sealed and the Π was connected to the vacuum system, and the vacuum system was disconnected after the pressure of 1 (1 Pa) and the drain (5 was sealed). Example 2 In the same manner as in Example 1, 127 0.003 1 0.196 0.003 = 0.075 g (II) was used, using a doped feed of the prepared mid-doped polyacetylene. iodine y 0.05 and the weight of polyacetylene m (PA) ----- 2.35 g • using iodine (i) and (Π) to calculate iodine weight: p doping process laboratory temperature was completed after four days P R E D Μ E T A method of homogeneously doping powdery polyacetylene with iodine vapors, characterized in that the vapor phase polymers of the polyacetylene and closed system are treated with vapor phase molecules at room temperature and an initial nitrogen pressure of 10 Pa. 2. An apparatus for the homogeneous doping of powdered polyacetylene with iodine vapors according to claim 1, characterized in that it comprises a container (1) of powdered polyacetylene provided with a sealant (2) of nitrogen and a container (4) of crystalline iodine. provided with a sealable outlet (3) of nitrogen wherein the containers are rigidly connected by a tube (3) containing a baffle and the two cartridges both coax the common horizontal axis and the entire associated structure is at one end in the bearing (6) o to the druhorn coupling (7 j fixed to the e-electromotor shaft (3).