JPWO2005085359A1 - Polymer nanodiamond composite - Google Patents

Abstract

The present invention relates to a polymer nanodiamond composite. The production method according to the present invention is characterized in that nanodiamonds are pretreated, subjected to a dispersion treatment in advance so that the nanodiamonds are sufficiently dispersed in the polymerization solvent during the polymerization reaction, and then polymerized.

Description

  The present invention relates to a polymer nanodiamond composite and a method for producing the same.

  Conventionally, hybrid materials composed of polymers and various inorganic materials have been researched and developed. In particular, there is an attempt to modify a polymethyl methacrylate (PMMA) -based polymer that is excellent in transparency and strength to impart preferable physical properties. However, these materials are manufactured by mixing a base polymer and an inorganic material, and therefore the obtained material is a macro order such as a simple dispersion of an inorganic material or a sea-island structure in a matrix of a base polymer. (Or semi-micro order). The physical properties of the material also changed the physical properties of the base polymer only slightly.

  In recent years, with the spread of various application fields, new materials having completely new physical properties are expected to appear. However, these conventional hybrid materials do not satisfy these requirements.

  A polymer nanodiamond composite is provided. In particular, it is an object to provide a hybrid material composed of a PMMA polymer and nanodiamond having transparency and excellent strength, and a method for producing the hybrid material.

  In view of the above expectation, the present inventor has conducted intensive research to develop a hybrid material having a novel structure having a completely new function applicable to a wide range of technical fields. As a result, in the presence of pretreated nanodiamond, the organic solvent It was found that a composite of polymer and nanodiamond can be produced by conducting a polymerization reaction in the medium. The present invention has been completed based on such findings.

  That is, the present invention is a completely new hybrid material using nanodiamond and organic polymer, and is a material having a nanostructure in which the nanomaterial is sufficiently dispersed in a polymer and has formed a strong interaction.

  In particular, the present invention is a hybrid material in which the polymer is a polymethylmethacrylate (PMMA) system, having sufficiently high transparency, high heat resistance, and high hardness.

  The present invention also relates to a method for producing such a hybrid material, wherein the monomer is polymerized in an appropriate organic solvent in which pretreated nanodiamonds are dispersed.

  The production method according to the present invention is a method in which nanodiamonds are pretreated and sufficiently dispersed in an organic solvent, and a polymer is polymerized in the presence of the nanodiamonds. Nevertheless, a polymer nanodiamond composite having very greatly improved physical properties (transparency, heat resistance) can be obtained.

FIG. 1 shows a hybrid DMA curve obtained with "dispersion" conditions. FIG. 2 shows a hybrid DMA curve obtained with "dispersion / filtration" conditions. FIG. 3 shows the DMA curve of the hybrid obtained under “purification / dispersion” conditions. FIG. 4 shows the DMA curve of the hybrid obtained under “purification / dispersion / filtration” conditions. FIG. 5 shows the strain stress curve of the hybrid obtained with PMMA and “purification / dispersion / filtration” conditions. FIG. 6 shows a DMA curve showing a comparison between wet and dry processes. FIG. 7 shows a DMA curve showing the time course of purification (wet) in purification / dispersion / filtration. FIG. 8 shows a comparison of DMA curves with different size and crystallinity differences.

(Polymer nano diamond composite)
The composite according to the present invention is characterized in that the polymer and nanodiamond interact strongly to form a nanostructure. Such a structure cannot be obtained at all by a conventional manufacturing method, and is a structure that has not been known at all. This structure differs greatly from that obtained by a simple blend of a conventional polymer and nanodiamond, and is a conventional method. This is also different from that obtained by conducting a polymerization reaction in the presence of nanodiamond. This is also evident from the differences in thermal and mechanical behaviors inherently, as will be apparent from the following examples.

(Production method)
The polymer used in the present invention is not particularly limited, and various types of polymers generally known as base polymers (matrix polymers) having desirable physical properties can be selected. Specific examples include polymethyl methacrylate, polystyrene, and polycarbonate. In the present invention, a polymethyl methacrylate type is particularly preferable. These copolymers are also included.

  The nano diamond used in the present invention can be used without limitation as long as it is a commercially available product and is known as a nano-sized diamond (specifically, manufactured by Izumi Tech Co., Ltd.).

  The production method according to the present invention is characterized in that the nanodiamond is pretreated. Commonly available nano-sized diamonds usually form secondary or higher order aggregates. Therefore, most of the nano-sized diamonds exist as aggregates and have a black to gray color.

  The present inventor has found that a composite according to the present invention can be obtained by carrying out a dispersion treatment in advance so that nanodiamonds are sufficiently dispersed in a polymerization solvent during the polymerization reaction. Based on this knowledge, dispersion that improves reproducible physical properties by examining in detail the degree of dispersion treatment and physical properties of the obtained hybrid material, including dispersion using an ultrasonic homogenizer, which is a commonly known dispersion treatment You can find the conditions.

  Specifically, in a polymerization solvent used for polymerization of a desired polymer, (1) nano-diamond is dispersed for an appropriate time with an ultrasonic homogenizer (hereinafter referred to as “dispersion”), and (2) the dispersed solution is Filter paper is used to filter paper (hereinafter referred to as “dispersion / filtration”). (3) The nanodiamond residual collected by suction filtration is dispersed again in the solvent (hereinafter referred to as “purification / dispersion”). (4) A process of dispersing nano-diamond residues collected by suction filtration again in a solvent and further filtering (hereinafter referred to as “purification / dispersion / filtration”).

  In addition, it is possible to use the residue obtained by suction filtration above while wet with a solvent (wet type) and to use the residue obtained by washing the residue with acetone and vacuum drying (dry type).

  On the other hand, the nanodiamond dispersion in the solvent obtained by the above pretreatment may gradually reagglomerate and cause variations in the physical properties of the polymer. Therefore, it is preferable to use it immediately after pretreatment. Whether or not nanodiamonds are sufficiently dispersed in a solvent can be qualitatively determined by their colors (transparent, gray, black). It is also possible to know the dispersion state using various known dispersion evaluation devices.

  It is characterized in that it penetrates inside and in the vicinity of nanometer-order pores of nanomaterials to form a network. Such a microstructure could not be manufactured at all by conventional manufacturing methods.

  In the production method according to the present invention, as described above, first, a dispersion solution prepared by pre-treating nanodiamond as described above is prepared in a suitable polymerization solvent, and necessary monomers are introduced therein. Further, the monomer is polymerized using generally known polymerization conditions.

  Accordingly, the polymerization reaction conditions are not particularly limited, and the selected solvent, reaction temperature, reaction pressure, necessary catalyst, and the like can be appropriately selected. Preferably, radical polymerization is performed in the presence of a radical polymerization initiator that can be initiated at an appropriate temperature. Specifically, in the case of methyl methacrylate, the polymerization conditions (solvent, temperature, polymerization initiator, reaction time) are preferably about 80 ° C. in toluene and AIBN is used as the polymerization initiator for about 24 hours.

  For the post-treatment of the polymerization reaction, generally known separation and purification methods can be used.

  Examples will be described in more detail below.

(Pre-distribution processing)
Monomer PMMA and solvent toluene were used.

  "Dispersion": 0.1 g of nanodiamond was added to 25 ml of toluene and subjected to an ultrasonic homogenizer for 30 minutes. Result: The sample was black and showed variations in physical properties.

  “Dispersion / filtration”: 0.1 g of nanodiamond added to 25 ml of toluene and filtered with an ultrasonic homogenizer for 1 hour using a filter paper (No. 2) Result: The sample was transparent, but the physical properties The variation was seen.

  “Purification / dispersion”: 0.1 g of nanodiamond is added to 25 ml of toluene, and the mixture that has been applied to an ultrasonic homogenizer for 30 minutes is suction filtered (10 μm), and 25 ml of toluene is added to the residue again. Homogenizer run for 30 minutes (during reprecipitation, decantation was performed to remove nanodiamond precipitate) Result: Although the sample was black, the reproducibility of the physical properties could be confirmed.

  “Purification / Dispersion / Filtration”: 0.1 g of nanodiamond is added to 25 ml of toluene, filtered through an ultrasonic homogenizer for 30 minutes by suction filtration (10 μm), and 25 ml of toluene is added to the residue again. What was passed through an ultrasonic homogenizer for 30 minutes and was filtered with a filter paper (No. 2). Result: The sample was transparent and the reproducibility of physical properties could be confirmed.

  “Wet, dry”: In the purification / dispersion / filtration operation, 0.1 g of nanodiamond was added to 25 ml of toluene, and the mixture that was applied to an ultrasonic homogenizer for 30 minutes was suction filtered (10 μm). What was used for the next operation while wet (wet) and washed with acetone, then placed in a vacuum dryer for 30 minutes and then used for the next operation (dry) Result: The difference in physical properties between the two I couldn't.

  “Change with time”: In the purification / dispersion / filtration operation, 0.6 g of nanodiamond was added to 150 ml of toluene, and the residue (wet) was removed by suction filtration (10 μm) over 30 minutes using an ultrasonic homogenizer. Was stored in toluene, collected in an appropriate amount over the course of the day, added again with 25 ml of toluene, and filtered through an ultrasonic homogenizer for 30 minutes using filter paper (No. 2). The same physical properties as on the day were observed, but the physical properties thereafter decreased.

  “Particle size / particle size distribution”: 50 nm single crystal and 50 nm polycrystalline nanodiamond were prepared by purification / dispersion / filtration operation. The 250 nm single crystal and 250 nm polycrystalline nanodiamond were prepared by a dispersion / filtration operation (however, suction filtration (0.45 μm) was used instead of filter paper; dispersion time was 30 minutes). As shown in FIG. 8, a large effect was observed when a single crystal was used. Specifically, the polycrystal shifted to about 3 ° C on the high temperature side, but the single crystal shifted to about 30 ° C on the high temperature side.

(polymerization)
The polymerization conditions are generally 10 g of methacrylic acid as a monomer in a dispersion in which nanodiamonds are dispersed in various degrees (“dispersion”, dispersion / filtration ”,“ purification / dispersion / filtration ”, and wet, dry). Methyl and 0.0164 g of α, α′-azobisisobutyronitrile as a polymerization initiator were added, and after substitution with nitrogen, polymerization was carried out at 80 ° C. for 24 hours. Thereafter, the polymerization solution was diluted with tetrahydrafuran and added dropwise to n-hexane for reprecipitation.

Example 1
Black single-crystal nanodiamond (ND, manufactured by Izumi Tech Co., Ltd.) with a particle size of about 50 nm is added to 25 ml of toluene so as to be 1 wt% with respect to methyl methacrylate (MMA), and dispersed for 0.5 hour with an ultrasonic homogenizer. Went. This dispersion liquid contained a large amount of soot that was present as a by-product during the production of ND and strengthened secondary aggregation of ND, and this was removed by suction filtration (purified ND). The obtained residue was again added to the same amount of toluene and dispersed again with an ultrasonic homogenizer. Furthermore, the filtrate obtained by removing non-dispersed ND with filter paper was used as the ND dispersion.

  MMA and AIBN were added to this dispersion and polymerized at 80 ° C. for 24 hours. After the reaction, the polymerization solution was diluted with THF and added dropwise to hexane for reprecipitation.

  The physical properties of the obtained hybrid were measured by dynamic viscoelasticity (DMA) or the like (see FIGS. 1 to 6). In the DMA curve of the hybrid, the temperature at which the storage elastic modulus E ′ decreased and the peak top of tan δ both shifted to the high temperature side by about 30 ° C. compared to PMMA alone, and a reproducible and highly transparent hybrid was obtained. The ND content in the prepared hybrid was 0.1 wt% or less.

  (Example 2) The purified ND of Example 1 was stored in toluene, and changes over time before preparation of the ND dispersion were examined. As a result (see FIG. 7), the hybrid prepared on the 4th day maintained the physical properties immediately after, but the physical properties gradually decreased from the 6th day, and on the 8th day, the DMA curve became almost the same as that of PMMA alone. Improvement is no longer recognized. This is presumably because ND dispersed to some extent during purification reaggregates with time.

  A comparison of DMA curves with differences in size and crystallinity is shown in FIG.

The composite according to the present invention is characterized in that a polymer and nanodiamonds interact strongly to form a structure. Such a structure cannot be obtained at all by a conventional manufacturing method, and is a structure that has not been known at all. This structure differs greatly from that obtained by a simple blend of a conventional polymer and nanodiamond, and is a conventional method. This is also different from that obtained by conducting a polymerization reaction in the presence of nanodiamond. As is apparent from the following examples, this is also evident from the difference in thermal and mechanical behavior from these, and can be applied as a basic material in a wide range of fields.

Claims (3)

  A polymer nanodiamond composite composed of nanodiamond and organic polymer.   A polymer nanodiamond composite having a sufficiently high transparency, high heat resistance and high hardness, wherein the polymer is polymethyl methacrylate (PMMA). A method for producing a polymer nanodiamond composite comprising nanodiamond and an organic polymer, characterized by pre-dispersing so that nanodiamonds are sufficiently dispersed in a polymerization solvent during the polymerization reaction, and then performing a polymerization reaction .

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