JPS58201810A - Preparation of polymer of thermally reversible hydrophilic-hydrophobic type - Google Patents

Abstract

PURPOSE:To obtain the titled polymer useful as a sunproofing material, providing an aqueous solution which is hydrophilic and transparent at <=a certain temperature, and becomes hydrophobic and untransparent at a temperature higher than it, by polymerizing N-isopropylacrylamide in a solid phase. CONSTITUTION:N-Isopropylacrylamide is polymerized in a solid phase by irradiation, irradiation with electron rays in such a way that it is kept at a temperature its melting point and the reaction temperature is lower than the melting point, to give the desired polymer. The prepared polymer has 22-27 deg.C transition temperature.

Description

[Detailed description of the invention] Uninvented: A polymer that dissolves in water at low temperatures and becomes wet, but becomes insoluble in water at high temperatures! ! ! Regarding the method of sending
More specifically, the present invention relates to a method for producing a hydrophilic-hydrophobic thermoreversible polymer characterized by face phase polymerization of N-isopropylacrylamide.

When in contact with water, an organic polymer compound dissolves or swells under low temperature conditions, becomes insolubilized and precipitates under high temperature conditions, and then melts when cooled again to form a swollen state in an aqueous solution. Based on its reversible properties, it is being used in a wide range of applications, including water-based adhesives, coatings, textile printing agents, textiles, and light shielding materials.

Regarding shading objects, greenhouses, frame houses,
Transparent walls such as open windows and windows for lighting in houses and factories can cause the internal temperature to rise more than necessary under the scorching summer sun. It is necessary to block the Until now, such light blocking means have included curtains, curtains,
Predetermined transparent parts were covered with light-shielding objects such as blinds to block the interior from direct sunlight.

However, this method is cumbersome in that it is necessary to determine whether or not light shielding is necessary and to attach or remove the light shield each time.

Therefore, if the transparent part is formed with a temperature-sensitive material that allows light to pass through when the sunlight is weak, but when the sunlight becomes stronger than necessary and the internal temperature rises, it will no longer be able to pass through. The polymer of isopropylmethacrylamide is hydrophilic below a certain temperature and its aqueous solution is transparent, but above that temperature it becomes hydrophobic and becomes opaque. We found that this property has the same property as that of a light-shielding material, and proposed that this property be used as a light-shielding material.

However, since the N-isopropylacrylamide polymer obtained by solution polymerization has a high transition temperature between hydrophilicity and hydrophobicity of 29 to 30°C, its range of use is considerably limited.

The inventors continued their research to develop a material with an even lower transition temperature and a wider range of uses, and as a result, N-
The inventors have discovered that the objective can be achieved by subjecting isopropylacrylamide to solid phase polymerization, and have accomplished the present invention based on this knowledge.

That is, the present invention provides a method for producing a hydrophilic-hydrophobic thermoreversible polymer, which is characterized by carrying out in-phase polymerization of N-isopropylacrylamide.

N-isopropylacrylamide used in the method of the present invention has a melting point of 64 to 65°C and is a colorless 7-mer needle-like crystal at room temperature. - It is thought that the hydrogen bond between the amide groups weakens as the temperature rises, resulting in insolubilization above the transition temperature.

In the method of the present invention, it is necessary to carry out solid phase polymerization by keeping N-isopropylacrylamide below the melting point and preventing the reaction temperature from exceeding the melting point. The polymerization method can be carried out by commonly known solid phase polymerization methods such as radiation irradiation, electron beam irradiation, etc.

In addition, in the method of the present invention, N-isopropylacrylamide supported on a porous carrier such as silica gel, alumina gel, porous polymer beads, etc. is irradiated with radiation to form a hydrophilic-hydrophobic thermoreversible polymer-porous carrier. Preparing sex carrier complexes is less variable.

According to the XIJ diffractogram, the polymer obtained by the uninvented method is an amorphous polymer, partially crosslinked and swollen in the solvent, and partially soluble in the solvent. The number of crosslinked portions increases.

In the method of the present invention, if N-iso-10-vinyl acrylamide is heated above its melting point, it will dissolve, so if it is placed in a container of any shape and then cooled for solid phase polymerization, it can be made into a hydrophilic material of any shape.
Hydrophobic thermoreversible polymers can be synthesized.

Such a polymer obtained by the method of the present invention dissolves or swells in water at discharge temperatures above the transition point, and does not dissolve in water and precipitates as a solid at temperatures above the transition point; When cooled, it dissolves in water again or swells in water. Such hydrophilic-hydrophobic thermoreversible polymers can be used in a wide variety of applications by utilizing their reversibility, and are expected to be used in a wider range of applications.

Next, the present invention will be explained in more detail with reference to Examples.

Example N - 40 of isopropylacrylamide was placed in an ampoule, and after vacuum degassing was performed using liquid nitrogen to remove air, the upper part was sealed with a burner. In addition, r from cobalt
wJ was irradiated for a predetermined time at a temperature of 23°C and an irradiation dose rate of 0.17M1%/hr. Next, the solid in the ampoule was poured into diethyl ether to precipitate BoIJ (N-isopropylacrylamide). The results are shown in Table 1 and FIG.

The obtained polymer was accompanied by gelation, and therefore viscosity measurement was impossible.

The obtained poly(N-isopropylacrylamide) and water were placed in a sealed aluminum container, covered with a sealed cell lid, and sealed with a sample sealer. The sample was subjected to calorimetry (DSOfi!A constant) using a differential scanning calorimeter at a heating rate of l''C/min. The results are shown in Table 1 and FIG.

The polymer obtained in Experiment 5 in Table 1 was extracted with acetone, and the acetone-soluble portion was poly(N-isopropylacrylamide)2. oq, water 13.4wv17) A Di90 curve was determined and the results are shown in FIG.

Table 1

[Brief explanation of the drawing]

Figure 1 is a graph showing the relationship between the yield of solid phase polymerization of N-isopropylacrylamide and radiation irradiation time, and Figure 2 is a graph showing the relationship between transition temperature and radiation irradiation time.
FIG. 3 is a graph showing the D80 curve of poly(N-isopropylacrylamide) aqueous solution. Patent claimant Makoto Ishizaka, Director General of the Agency of Industrial Science and Technology -tm
4o Tsukudasho (1()1!ili Yari punishment)
Noodles (p)

Claims (1)

[Claims] A method for producing a hydrophilic-hydrophobic thermoreversible polymer, which comprises solid-phase polymerizing IN-isopropylacrylamide.