Synthesis method and application of trehalose-modified PNIPAm temperature-sensitive smart hydrogel

Abstract

The present invention relates to a synthesis method and application of a trehalose-modified PNIPAm thermosensitive smart hydrogel, and the synthesis method comprises the following steps: 1. Adding N-isopropylacrylamide and N,N'-methylenebisacrylamide to a trehalose solution respectively and mixing to obtain a mixed solution; 2. Adding ammonium persulfate to the mixed solution of the previous step and stirring; 3. Adding N,N,N',N'-tetramethylethylenediamine to the mixed solution of the previous step and stirring to obtain a gel solution; 4. Placing at 20-30°C for 2-3 hours to obtain a trehalose-modified PNIPAm thermosensitive hydrogel. The present invention provides a simple preparation process of a trehalose-modified PNIPAm-Trehalose thermosensitive hydrogel and a method for a trehalose-modified PNIPAm-Trehalose smart window, which opens up a new way for building energy conservation.

Description

Technical Field

[0001] The invention relates to the field of hydrogel synthesis methods, and in particular to a synthesis method and application of trehalose-modified PNIPAm temperature-sensitive intelligent hydrogel. Background Art

[0002] PNIPAm thermosensitive hydrogel was synthesized by in situ polymerization in deionized water. Since PNIPAm is a single-network thermosensitive hydrogel, its mechanical strength is poor, and its durability and reusability are low; in addition, the thermal response rate of PNIPAm thermosensitive hydrogel is also slow, ΔT sol and ΔT lum It is not ideal and not conducive to practical application. Summary of the invention

[0003] A method for synthesizing trehalose-modified PNIPAm temperature-sensitive smart hydrogel comprises the following steps:

[0004] Step 1, trehalose (0, 2, 4 and 6 g) was dissolved in 20 ml of deionized water to form trehalose solutions with mass fractions of 0%, 10%, 20% and 30%, respectively;

[0005] Step 2, adding N-isopropylacrylamide and N,N'-methylenebisacrylamide to the trehalose solution in step 1 respectively and mixing them evenly to obtain a mixed solution; the mass ratio of the trehalose solution, N-isopropylacrylamide and N,N'-methylenebisacrylamide is 20:(1-2):(0.01-0.03);

[0006] Step 3, adding ammonium persulfate to the mixed solution of step 2 and stirring, wherein the mass ratio of the trehalose solution to the ammonium persulfate is 20:(0.01-0.03);

[0007] Step 4, adding 4-7 μm N,N,N′,N′-tetramethylethylenediamine to the mixed solution of step 3, and stirring to obtain a gel solution;

[0008] Step 5: Place the mixture at 20-30° C. for 2-3 hours to obtain the trehalose-modified PNIPAm thermosensitive hydrogel.

[0009] Furthermore, the mass ratio of the trehalose solution, N-isopropylacrylamide and N,N'-methylenebisacrylamide is 20:1.34:0.02.

[0010] Furthermore, in step 3, the mass ratio of ammonium persulfate to deionized water is 20:0.02.

[0011] Furthermore, the mass fraction of trehalose in the trehalose solution in step 1 is 30%.

[0012] The application of trehalose-modified PNIPAm thermosensitive smart hydrogel in thermosensitive smart windows is as follows: a layer of trehalose-modified PNIPAm hydrogel is coated on the upper surface of a glass slide, and a layer of glass slide is covered on the upper surface of the trehalose-modified PNIPAm hydrogel to form a sandwich structure. Finally, the trehalose-modified PNIPAm hydrogel is sealed with a sealant to obtain a trehalose-modified PNIPAm thermosensitive hydrogel smart window.

[0013] The beneficial effects of the present invention are as follows: the present invention uses a physical crosslinking method to prepare a PNIPAm single network thermosensitive hydrogel into a trehalose-modified PNIPAm double network thermosensitive hydrogel, and the prepared trehalose-modified PNIPAm double network thermosensitive hydrogel is well applied to smart windows, and the energy loss of buildings is well reduced. Compared with the prior art, the trehalose-modified PNIPAm thermosensitive smart material of the present invention has the following advantages: (1) The PNIPAm single network hydrogel is prepared into a trehalose-modified PNIPAm double network hydrogel by a physical crosslinking method, which not only improves the mechanical strength of the PNIPAm thermosensitive hydrogel, but also improves its thermal response rate; the addition of trehalose not only solves the problem of volume change after the phase transition of the ordinary PNIPAm thermosensitive hydrogel, but also slightly reduces the LCST of PNIPAm. The prepared trehalose-modified PNIPAm double network thermosensitive hydrogel is well applied to smart windows, and the strong mechanical strength can enhance the reusability of the trehalose-modified PNIPAm thermosensitive smart window, which is more conducive to practical application. In addition, the trehalose-modified PNIPAm smart window can achieve excellent optical properties, high light transmittance, high solar modulation, and has excellent energy-saving performance. (2) Unlike previous methods, the physical crosslinking method of the present invention is simple to operate, non-toxic, low-cost and environmentally friendly. More importantly, the trehalose-modified PNIPAm thermosensitive material is currently a very promising energy-saving and climate-adaptive smart window material. (3) The present invention uses N,N,N′,N′-tetramethylethylenediamine as a catalyst to accelerate the reaction rate and quickly promote cross-linking between monomers, making the formed hydrogel more transparent, uniform, and more conducive to practical applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 Schematic diagram of the synthesis of trehalose-modified PNIPAm thermosensitive smart hydrogel. DETAILED DESCRIPTION

[0015] The following is a description of the principles and features of the present invention. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0016] (1) Synthesis of Trehalose-modified PNIPAm Thermosensitive Hydrogel

[0017] like Figure 1 As shown in the figure, PNIPAm and trehalose (Trehalose) were used as raw materials to successfully prepare PNIPAm-Trehalose hydrogel with thermosensitive properties through a simple physical cross-linking method. The main steps are as follows:

[0018] ① Trehalose (0, 2, 4 and 6 g) was dissolved in 20 ml of deionized water to form trehalose solutions with mass fractions of 0%, 10%, 20% and 30%, respectively.

[0019] ② Add 1.34 g (0.07 mol) of (N-isopropylacrylamide) (NIPAm) and 0.02 g (0.0014 mol) of N,N'-methylenebisacrylamide (MBA) to trehalose solutions of different concentrations;

[0020] ②Mix evenly;

[0021] ③ Stir for 30-60 minutes to obtain a uniform and transparent solution;

[0022] ④ Add 0.02g ammonium persulfate (APS);

[0023] ⑤Continue stirring for 30-60 minutes;

[0024] ⑥ Add 6 μm N,N,N′,N′-tetramethylethylenediamine (TEMED);

[0025] ⑦Continue stirring for 3 minutes;

[0026] ⑧ Place at room temperature (20°C) for 2-3 hours to obtain trehalose-modified PNIPAm thermosensitive hydrogel;

[0027] Experimental comparison: PNIPAm and trehalose were dissolved in 20 ml of deionized water at a mass ratio of 1:0-1:30.

[0028] Example 1: 1: 0, the LCST of the thermosensitive material is 32° C., and the volume shrinks by 20% after the phase change.

[0029] Example 2: 1:10, the LCST of the thermosensitive material is 31°C, and the volume shrinks by 15% after the phase change.

[0030] Example 3: 1:20, the LCST of the thermosensitive material is 29°C, and the volume shrinks by 10% after the phase change.

[0031] Example 4: 1:30, the LCST of the thermosensitive material is 28.5°C, and the volume shrinks by 3% after the phase change.

[0032] It can be seen from Examples 1-4 that the LCST of the thermosensitive material with the addition of trehalose is significantly reduced, and the volume shrinkage is significantly reduced. Among them, the solution of Example 4 has the smallest volume shrinkage, the largest LCST reduction, and the best effect.

[0033] Smart windows based on PNIPAm have disadvantages such as fragility, water loss, volume shrinkage, delayed temperature response, and LCST higher than the comfortable temperature for the human body. In the present invention, a simple method is developed to prepare a new PNIPAm-Trehalose thermosensitive hydrogel. The addition of trehalose significantly reduces the LCST of the PNIPAm hydrogel and greatly improves the thermal response rate of the PNIPAm hydrogel; more importantly, the trehalose-modified PNIPAm hydrogel solves the problem of volume shrinkage before and after the phase change of ordinary PNIPAm hydrogel. This high-performance temperature-responsive PNIPAm-Trehalose hydrogel can promote the development of the thermochromic smart window area and provide a new design scheme for energy-saving materials.

[0034] (2) Preparation of trehalose-modified PNIPAm temperature-sensitive smart window

[0035] The experiment used a glass slide as a substrate. First, a certain amount of trehalose-modified PNIPAm hydrogel was added to the front of a glass slide, then covered with a layer of glass slide to form a sandwich structure, and finally sealed all around with a sealant. The high-transmittance glass slide used a 7101 sailboat board with a size of 47.0mm×20.5mm. Samples with thicknesses of 0.5, 0.75, and 0.10mm were successfully produced, and trehalose-modified PNIPAm thermosensitive hydrogel smart windows were obtained. In addition, the seal is tight to prevent water evaporation, ensuring safety and durability in actual use. The trehalose-modified PNIPAm hydrogel film can remain completely transparent at room temperature below the LCST, but becomes translucent at temperatures above the LCST, which can effectively prevent solar radiation.

[0036] (3) Characterization

[0037] The present invention utilizes the synergistic effect of hydrophilic and hydrophobic groups and selects polymer monomers containing two terminal groups to synthesize a functional polymer with low-temperature thermochromic properties.

[0038] The chemical structure of new materials is determined by IR, MS, elemental analysis and other characterization methods; the absorption spectrum of new polymers is characterized by UV; the thermophysical properties of polymer materials are characterized by TGA and DSC to determine their glass transition temperature and LCST; the rheological parameters of polymers at different temperatures are determined by rheometer.

[0039] The internal microstructure of the polymer was measured by SEM, TEM, and AFM to explore the construction of the hydrophilic-hydrophobic network interpenetrating structure. The morphology of the smart polymer film was changed by mixing solvents, additives, etc. to determine the effect of morphology on transmittance.

[0040] Characterization of polymer transmittance and ΔT at different temperatures by UV-VIS-NIR sol ,ΔT lum ,ΔT IR changes, thereby determining the thermal insulation and other functional effects of the smart polymer film.

[0041] The mechanical properties of the polymers were studied. Compared with the polymerization of PNIPAm monomers, the physically cross-linked trehalose-modified PNIPAm smart hydrogels have the characteristics of small volume swelling, easy molding, high tensile strength and toughness. Based on our previous research, we have rich experience in synthesizing physically cross-linked network smart polymer hydrogels, and the mechanical properties will be significantly improved.

[0042] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for synthesizing trehalose-modified PNIPAm temperature-sensitive smart hydrogel, characterized in that: The following steps are involved: Step 1, dissolving trehalose in deionized water to form a trehalose solution with a mass fraction of 10-30%; Step 2, adding N-isopropylacrylamide and N,N'-methylenebisacrylamide to the trehalose solution in step 1 respectively and mixing them evenly to obtain a mixed solution; the mass ratio of the trehalose solution, N-isopropylacrylamide and N,N'-methylenebisacrylamide is 20:1.34:0.02; Step 3, adding ammonium persulfate to the mixed solution of step 2 and stirring, wherein the mass ratio of the trehalose solution to the ammonium persulfate is 20:(0.01-0.03); Step 4, adding 4-7 μM N,N,N′,N′-tetramethylethylenediamine to the mixed solution of step 3, and stirring to obtain a gel solution; Step 5: Place the mixture at 20-30° C. for 2-3 hours to obtain the trehalose-modified PNIPAm thermosensitive hydrogel.

2. The method for synthesizing the trehalose-modified PNIPAm temperature-sensitive smart hydrogel according to claim 1, characterized in that: In step 3, the mass ratio of trehalose solution to ammonium persulfate is 20:0.

02.

3. The method for synthesizing the trehalose-modified PNIPAm temperature-sensitive smart hydrogel according to claim 1, characterized in that: The mass fraction of trehalose in the trehalose solution in step 1 is 30%.

4. Application of the trehalose-modified PNIPAm thermosensitive smart hydrogel prepared by the method of any one of claims 1 to 3 in a thermosensitive smart window, characterized in that: The specific application method is: coating a layer of trehalose-modified PNIPAm thermosensitive smart hydrogel on the upper surface of a glass slide, covering a layer of glass slide on the upper surface of the trehalose-modified PNIPAm thermosensitive smart hydrogel to form a sandwich structure, and finally sealing the hydrogel with sealant to obtain a trehalose-modified PNIPAm thermosensitive hydrogel smart window.

Images