RU2494036C2 - Method of preparation of polymeric nanocomposites using carbon nanotubes by method of casting from solutions - Google Patents

Abstract

FIELD: nanotechnology.

SUBSTANCE: invention relates to a method of preparation of polymeric nanocomposites which can be used in development and creation of new types of polymeric materials and coatings. The method consists in the fact that homogeneous sedimentation stable colloidal solutions are applied on the substrate by casting, and after casting the solvent is removed. The colloidal solution comprises a solvent, a polymer matrix - plasticised water-insoluble polyvinyl chloride, and functionalised carbon nanotubes (CNTs). The functionalised carbon nanotubes are used as purified multi-walled carbon nanotubes with grafted methacrylic groups, modified by the method of covalent functionalisation. The solvent is used as the nonaqueous organic media.

EFFECT: invention enables to extend the range of used polymer matrices, and to adjust purposefully in the quantitative and qualitative levels the complex of operational and technological properties of nanocomposites.

1 tbl, 6 ex

Description

The invention “A method for producing polymer nanocomposites using carbon nanotubes by irrigation from solutions” relates to the field of physical chemistry of polymers, in particular, to obtain polymer nanocomposites by irrigation from a solution by introducing carbon nanotubes (CNTs) functionalized from the outer surface into a plasticized matrix and can be used in the development and creation of new types of polymer and materials and coatings.

The level of technology. It is known that the use of CNTs uniformly distributed in them in polymer composites helps to give them unusual electrical, mechanical, and electrophysical properties, and, as a consequence, the diversity of their practical use [1].

However, as practice shows, the effect of CNTs on the properties of nanocomposites substantially depends on the nature of the distribution of CNTs in them, i.e. the degree of their dispersion in the polymer matrix [2,3]. That is why considerable attention is paid to the development of methods that ultimately improve the possibility of dispersion of CNTs in a polymer matrix [4]. The most convenient and effective in this regard is the method of producing CNTs of nanocomposites by irrigation from solution. However, since CNTs themselves are, as a rule, practically insoluble in any of the known solvents, using this method to create a sedimentation-resistant colloidal solution usually requires the functionalization of the outer surfaces of CNTs. In this case, either covalent modification methods (through chemical grafting of certain chemical groups) or non-covalent methods (through the use of specially selected surface-active substances (surfactants) [5]) are used.

Most of the work on the dispersion of CNTs in solutions and the preparation of polymer nanocomposites from them by irrigation was carried out using water-soluble polymer matrices [2, 3, 6]. At the same time, there are almost no works on the use of water-insoluble, including plastiocated polymer matrices.

As a prototype, it is possible to obtain optically transparent homogeneous films using carboxymethyl cellulose and single-walled carbon nanotubes [6]

The aim of the present invention is to expand the range of used polymer matrices, as well as expanding the possibilities of targeted regulation of the complex of operational and technological properties of polymer CNT nanocomposites obtained by irrigation from sedimentation-resistant colloidal solutions. This goal is achieved by the fact that a water-insoluble plasticized polyvinyl chloride (PVC) is used as a polymer matrix, covalently modified multilayer CNTs (functionalized methacrylic acid 2-hydroxyethyl ester groups) as functionalized CNTs;

,

,

and as a solvent non-aqueous media (tetrahydrofuran (THF), and chloroform (CH ₃ Cl).

The features of the present invention are illustrated by the following examples.

Example 1 (prototype).

A colloidal solution is preliminarily prepared, where water is used as a solvent, as CNTs are crude single-walled nanotubes (SWCNTs) obtained by arc spraying, and as a polymer matrix, sodium salt of carboxymethyl cellulose (CMC), which simultaneously plays the role of a surfactant (surfactant) ), which ensures the functionalization of the outer surface of SWCNTs by the method of non-covalent (without formation of a chemical bond) modification. Moreover, the content of crude SWCNTs and CMC in the initial aqueous solution was 3.1 wt.% And 1.0 wt.%, Respectively. The resulting solution was subjected to ultrasonic treatment (dispersion) for 30 minutes. Then, in order to purify the insoluble precipitate, an ultracentrifugation operation was carried out for 1 hour. The obtained segmentation-stable, homogeneous solution containing purified OUNG and CMC (i.e., a polymer matrix that simultaneously plays the role of a surfactant) was further used to prepare the CMC-SWCNT nanocomposite by irrigation onto a substrate, followed by removal (evaporation) of the solvent (water) three room temperature.

Example 2

A 4 wt.% Solution of PVC plasticized with dioctyl phthalate (DOP) in a non-aqueous solvent (THF) with a mass ratio of PVC: DOP = 100: 50, respectively, is prepared in advance.

After obtaining a transparent homogeneous solution, purified multilayer CNTs are added to it, and for the functionalization of their outer surface by the method of non-covalent modification of surfactants (potassium salt of di- (alklipolyegylene-picoleic) ester of phosphoric acid, oxyphos-B, TU 6-02-1177-79) in a mass ratio PVC: DOP: CNT: Surfactant = 1: 0.5: 0.1: 1.0, respectively. The resulting solution was sonicated for 30 minutes. However, it was not subsequently used to obtain PVC-CNT nanocomposites due to the manifestation of excessive sedimentation instability (instant separation within 1-2 minutes after manufacture, i.e. inability to form a stable colloidal solution)

Example 3

It differs from Example 2 in that instead of non-covalently modified CNTs, oxyphosome-B uses covalently modified CNTs with the functional groups of methacrylic acid 2-hydroxyethyl ester,

,

,

The ultrasonic dispersion time was 10 minutes. Subsequently, the solution was subjected to centrifugation for 20 minutes. After separation of the precipitate, a homogeneous sedimentation-resistant (not stratifying for 3 months) optically transparent grayish colloidal solution was obtained, which was further used to obtain PVC-CNT nanocomposites by pouring onto a glass substrate followed by removal of a non-aqueous solvent (THF) at room and temperature .

Example 4

Weaned from example 3 in that the mass ratio of PVC: DOP is 100: 65, respectively.

Example 5

It differs from Example 4 in that modifier A is used as a plasticizer, which is a multicomponent homogeneous mixture of high boiling organic and inorganic acids and alcohols, alcohols and their derivatives (TU 2494-001-45907714-77).

Example 6

It differs from Example 5 in that chloroform (CH ₂ Cl) is used as a solvent.

The test results of the obtained colloidal solutions used directly during irrigation, as well as samples of PVC-CNT nanocomposites obtained with their help, are shown in the Table

As follows from the Table, the application of the proposed method allows us to expand the range of used polymer matrices through the use of plastioated water-insoluble PVC, and also allows us to purposefully control the range of its operational and technological properties on a quantitative and qualitative level.

For example:

- significantly (3 times) reduce the time of ultrasonic dispersion and centrifugation;

- significantly facilitate the removal of the nanocomposite from the substrate and its further use for practical purposes;

- purposefully change its operational properties (fragility temperature, elongation) through the use of various types of plasticizers and in different proportions with respect to the polymer (PVC).

Bibliography

1. Rakov E.G. // Advances in Chemistry, 2001, Vol. 20 (10), bs. 934-973.

2. Chemov A.I., Obraztsova E.D., Lobach A.S. // Physica Status Solidi (b). 2007.V.244. N 11. p. 4231.

3. Bokova S. N., Mamonova T. S., Obraztsova E. D., Sklyarova G. B., Shablygin M. V. // Chemical fibers. 2010. No4. S.26.

4. Anoshkin I.V. Chemical modification and fractionation of thin-layered carbon nanotubes. Diss. Ph.D. RCTU, named after D.I. Mendeleev ,. M.: 2008. Ch. 1.

5. ibid., Ch. 3.

6. ibid., Ch. 4.

Table Technological and operational properties of colloidal solutions and films of PVC-CNT nanocomposites obtained on their basis Properties of colloidal solutions Properties of PVC-CNT nanocomposites Appearance Sedimentation stability (no stratification or change in appearance Appearance Relative extension, % Fragility temperature, ° С one Homogeneous transparent gray solution More than 3 months Fragile, brittle gray film ~ 8 over plus 170 2 Black sedimentation separation n / a 1 min - - - 3 Homogeneous transparent gray solution More than 3 months Elastic, transparent film in dark gray 175 Minus 40 four Homogeneous transparent gray solution More than 3 months Elastic, transparent film in dark gray 245 Minus 45 5 Homogeneous transparent gray solution More than 3 months Elastic, transparent film in dark gray 330 Minus 60 6 Homogeneous transparent gray solution More than 3 months Elastic, transparent film in dark gray 329 Minus 60

Claims (1)

A method for producing polymer nanocomposites containing carbon nanotubes by pouring homogeneous sedimentation-resistant colloidal solutions containing a solvent, a polymer matrix and functionalized purified CNTs onto a substrate, followed by removal of the solvent after watering, characterized in that plasticized water-insoluble polyvinyl chloride (PVC) is used as the polymer matrix , as functionalized purified nanotubes - multilayer CNTs with grafted methacrylic groups, odifitsirovannye covalent functionalization method, and as a solvent - non-aqueous organic medium.