JPS58174408A - Preparation of copolymer thermally reversible from hydrophilic to hydrophobic or vice versa - Google Patents

Abstract

PURPOSE:To prepare the titled copolymer which is soluble in water at low temperature and insoluble at high temperature, and has arbitrarily controllable transition temperature, by the solution polymerization of N-isopropylacrylamide and N-isopropylmethacrylamide. CONSTITUTION:For example, N-isopropylacrylamide and N-isopropylmethacrylamide are dissolved in a solvent (e.g. N,N-dimethylformamide), and subjected to the solution polymerization in the presence of a polymerization initiator (e.g. azobisisobutyronitrile).

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a copolymer that is soluble in water at low temperatures but insoluble in water at high temperatures. The present invention relates to a method for producing a hydrophilic-hydrophobic thermoreversible copolymer whose transition temperature can be controlled from methacrylamide.

When in contact with water, organic polymer compounds dissolve under low temperature conditions, become insolubilized and precipitate under high temperature conditions, and furthermore, dissolve when cooled again to form an aqueous solution. Based on their reversible properties, for example, It is being used in a variety of fields, including water-based adhesives, coating agents, and printing agents.

However, since these organic polymer compounds only exhibit a specific transition temperature, their uses are inevitably limited.

Therefore, if it becomes possible to arbitrarily control the transition temperature of this type of compound, it is expected that its range of use will be significantly expanded.

Under these circumstances, the present inventors conducted intensive research to develop a hydrophilic-hydrophobic thermoreversible compound whose transition temperature can be controlled arbitrarily, and found that N-isopropylacrylamide and N- It was discovered that the object could be achieved by copolymerizing isopropyl methacrylamide, and the present invention was completed based on this knowledge.

That is, the present invention provides a method for producing a hydrophilic-hydrophobic thermoreversible copolymer, which comprises solution polymerizing N-isopropylacrylamide and N-isopropylmethacrylamide.

The N-isopropylacrylamide and N-isopropylmethacrylamide compounds used in the method of the present invention exhibit special behavior based on this substituent, especially the hydrogen bond between water and amide of the branched N-isopropylamide group in the polymer. It is thought that N-isopropylacrylamide and N-isopropyl methacrylamide as monomer components are heated above their melting point and dissolved. It is necessary to carry out solution polymerization using a solvent capable of dissolving the monomer components, or both of the above, as a reaction medium. There are no particular restrictions on such solvents, but examples include water, alcohols, N,N-dimethylformamide, N,N-diethylacetamide, dimethyl sulfoxide, acetone, dioxane, tetrahydrofuran, benzene, chloroform,
Examples include carbon tetrachloride, which may be used alone or in combination of two or more. In the polymerization reaction, the monomers are added to the above solvent! Usually 1
By any commonly known method such as dissolving at a concentration in the range of ~80% by weight and irradiating with radiation, heating in the presence of a radical polymerization initiator, or irradiation with light in the presence of a photosensitizer. It can be carried out.

The copolymer obtained by the method of the present invention has a transition temperature of 3
It has a transition temperature between poly(N-inpropylacrylamide) of 0.1°C and poly(N-inpropylmethacrylamide) with a transition temperature of 44.5°C, and also has a transition temperature between N-isopropylacrylamide and N-isopropylmethacrylamide. Since the transition temperature of the obtained copolymer varies within the above temperature range in a substantially proportional manner according to the blending ratio of the amide, a copolymer having a desired transition temperature can be easily obtained.

According to the method of the present invention, the proportion of each monomer used in the copolymerization reaction substantially matches the composition of the obtained copolymer. This can be easily confirmed by, for example, an R spectrum, an sNMR spectrum, or an elemental analysis.

As mentioned above, the thermoreversible copolymer obtained by the method of the present invention has a transition temperature determined by the proportion of monomers used, but other copolymerization conditions such as the type of medium,
The 7mer concentration of the solution, the means to start the copolymerization reaction, the type and dose of radiation, the type and amount of radical polymerization initiator, the type and amount of photosensitizer, and the type and amount of irradiation light, It varies somewhat depending on the temperature of the copolymerization system.

However, if the transition temperature of each single polymer of N-isopropylacrylamide and N-isopropylmethacrylamide under the set copolymerization conditions is determined,
A copolymer having a desired transition temperature can be easily obtained.

As the copolymer obtained by the method of the present invention, one having an appropriate high molecular weight, for example, one having an intrinsic viscosity of about 0.01 to 6.0 when measured at a temperature of 30°C using chloroform, is practical. Reeds, especially those with a thickness of 0.05 to 3.0 are preferred.

Such a copolymer obtained by the method of the present invention is
At temperatures below the transition point, it dissolves in water, and at temperatures above the transition temperature, it does not dissolve in water and precipitates as a solid; however, when this is cooled to a temperature below the transition temperature, it dissolves in water again and becomes a solution. The hydrophilic-hydrophobic thermoreversible copolymer can be used in a wide variety of applications by taking advantage of its reversibility, and it is expected that it will be used in a wide range of applications.

Next, the present invention will be explained in more detail by way of examples.

Example I Copolymers having various composition ratios were produced by changing the combined amounts of N-isopropylacrylamide and N-isopropylmethacrylamide. That is, N as a solvent,
Using N-dimethylformamide, add 0.599 ml of azobisinobutyronitrile to 250 ml and use 20 d of the dissolving solution to prepare a monomer solution, and react at a reaction temperature of about 100°C for about 25 hours. I let it happen. The polymers obtained by removing the solvent were measured for viscosity at a temperature of 30°C using chloroform to determine the intrinsic viscosity [η], and the weight % of N was determined by CHN measurement. ]N
- The fraction of inglovir methacrylamide was calculated.

The amount of monomer charged in each experiment, various measured values, and the respective transition temperatures of the obtained copolymers are summarized in the following table.

This table shows that the fraction of N-isopropylmethacrylamide in the polymer substantially matches the monomer fraction in the charged amount, and as the fraction increases, the transition temperature increases, and the degree of increase is due to measurement error. It can be seen that the ratio is proportional to the increase rate of the fraction within the range.

Further, an aqueous solution having a concentration of 1% was prepared using the copolymer A3 in Table 1, and the transmittance of light at 500 nm at different temperatures was measured. The results are shown in FIG. 1 as a graph.

From this graph, a sharp change in transmittance was observed at 33°C, and it was confirmed that the phase transition temperature of this copolymer in water was 33°C.

Example 2 Same as Example 1 (the amounts of N-isopropylacrylamide and N-isopropylmethacrylamide were changed to produce polymers with various composition ratios).

That is, a monomer solution was prepared using acetone 15- as a medium solvent, and the reaction temperature was 19°C and 4.5 x 105R.
Irradiation was performed for a predetermined time under the condition of /hr. After carrying out radiation polymerization in this manner, the reactant was converted into D-hexa/-benzene (s
o:so) mixture to recover the polymer. The viscosity of the obtained polymers was measured using chloroform at a temperature of 30°C to determine the intrinsic viscosity [η], and the weight percent of N was determined by CHN measurement. The fraction was calculated. The transition temperature was determined by preparing an aqueous solution with a concentration of 1%, measuring the transmittance of light at 500 nm while varying the temperature of the solution, and determining the temperature at which the transmittance was 1% as the transition temperature. In addition, the sample container was a sealed aluminum container at a heating rate of 1°C/min. Three measurements were performed using DS. In addition, the copolymer of A13 (A) and the copolymer of A15 (B
) and A18 polymer (0) at a heating rate of 1° C./min. DSC curves are shown in FIG.

[Brief explanation of drawings]

Figure 1 is a graph showing the relationship between temperature and light transmittance for a 1% aqueous solution of the copolymer obtained by the method of the present invention, and Figure 2 is a graph showing the relationship between poly(N-isopropylacrylamide), poly(N-isopropylacrylamide),
2 is a graph showing DSC curves of a copolymer of N-isopropyl methacrylamide) and N-isopropyl methacrylamide and N-isopropyl methacrylamide. Patent Applicant Makoto Ishizaka, Director of the Agency of Industrial Science and Technology - Governmental Procedures Amendment Book Showa Gakuen/OS Month 1-a L Case Indication 1982 Patent Application @4801 No. 1 2 Name of Invention Hydrophilicity - 1N Approved Method for producing a sexually mature evaporable Taki copolymer Gourd Relationship with the arrester case Patent applicant 1-chome Kasumigaseki, Chiyoda-ku, Tokyo @ @ No. 91 (114) Director of the Agency of Industrial Science and Technology Kawa 1) Hirobe 4 Designated agent & Shusho no Uchiharu a) Beak specification gz page Jlllff what's the ``invention of dawn J
is corrected to "name of the invention" and stored. ) Correct the MLg on page 11 as shown in the attached sheet. teeth

Claims (1)

[Claims] A method for producing a hydrophilic-hydrophobic thermoreversible copolymer, which comprises solution polymerizing IN-isopropylacrylamide and N-isopropylmethacrylamide.