![Synthesis of a novel UV-curable prepolymer 1,3-bis[(3-ethyl-3-methoxyoxetane)propyl]tetramethyldisiloxane and study on its UV-curing properties Cover](https://paradigm-files.s3.eu-central-1.amazonaws.com/MSP/cover-image.jpg)
Table 1
Materials and reagents.
| Materials and reagents | Purity (%) | Manufacturer |
|---|---|---|
| Diethyl carbonate | 99.7 | Sinopharm Chemical Reagent Co., Ltd |
| Trihydroxypropane | 99.7 | Sinopharm Chemical Reagent Co., Ltd |
| Anhydrous magnesium sulfate (solid) | Sinopharm Chemical Reagent Co., Ltd | |
| Potassium hydroxide (solid) | Tianjin Damao Chemical Reagent Factory | |
| Allyl bromide | 99.7 | Tianjin Damao Chemical Reagent Factory |
| Toluene | 99.9 | Xilong Chemical Co., Ltd |
| Dichloromethane | 99.7 | Xilong Chemical Co., Ltd |
| Tetrabutylammonium bromide | 99.7 | Xilong Chemical Co., Ltd |
| Triarylsulfonium hexafluoroantimonate (UV-6976) | 99.7 | Dow Union Carbide |
| 1,1,3,3-tetramethyldisiloxane | 99 | Shanghai Chuqing New Material Co., Ltd. |
| Karstedt catalyst | 99.5 | Shanghai Aladdin Technology Co., Ltd. |
| E-51 epoxy resin | 98 | Shanghai Resin Factory |
| 2021p alicyclic epoxy resin | 98 | Daicel (China) Investment Co., Ltd |
Fig. 1
Synthesis route of 3-ethyl-3-hydroxymethyloxetane and 3-ethyl-3-allylmethoxyoxetane.
Fig. 2
Synthesis route of the prepolymer.
Fig. 3
Dimensions of the designed samples.
Fig. 4
(A) The infrared spectrum of 3-ethyl-3-hydroxymethyloxetane. (B) The infrared spectrum of 3-ethyl-3-allylmethoxyoxetane.
Fig. 5
(B) The infrared spectrum curve of 3-ethyl-3-allylmethoxyoxetane. (C) The infrared spectrum curve of 1,1,3,3-tetramethyldisiloxane. (D) The infrared spectrum curve of the prepolymer.
Table 2
Analytical table of the 1H-NMR spectrum for the 3-ethyl-3-hydroxymethyloxetane.
| Location of H | Chemical shift /(δ/ppm) | Structural formula |
|---|---|---|
| 1 | 0.77 | 3H, -CH3 |
| 2 | 1.60 | 2H, -CH2- |
| 3 | 3.58 | 2H, -CH2- |
| 4 | 3.74 | H, -OH |
| 5 | 4.28 | 2H, -CH2- |
| 6 | 4.33 | 2H, -CH2- |
Fig. 6
1H-NMR spectrum of 3-ethyl-3-hydroxymethyloxetane.
Table 3
Analytical table of the 1H-NMR spectrum for the 3-ethyl-3-allylmethoxyoxetane.
| Location of H | Chemical shift/(δ/ppm) | Structural formula |
|---|---|---|
| 1 | 0.86 | 3H, -CH3 |
| 2 | 1.73 | 2H, -CH2- |
| 3 | 3.53 | 2H, -CH2- |
| 4 | 3.97 | 2H, -CH2- |
| 5 | 5.87 | H, -CH= |
| 6 | 5.24 | 2H, =CH2 |
| 7 | 4.36 | 2H, -CH2- |
| 8 | 4.42 | 2H, -CH2- |
Fig. 7
1H-NMR spectrum of 3-ethyl-3-allylmethoxyoxetane.
Fig. 8
1H-NMR spectrum of 1,1,3,3-tetramethyldisiloxane.
Table 4
Analytical table of the 1H-NMR spectrum for the 1,1,3,3-tetramethyldisiloxane.
| Location of H | Chemical shift/(δ/ppm) | Structural formula |
|---|---|---|
| 1 | 0.17 | 12H, -CH3 |
| 2 | 4.66 | 2H, -Si-H |
Table 5
Analytical table of the 1H-NMR spectrum for the prepolymer.
| Location of H | Chemical shift/(δ/ppm) | Structural formula |
|---|---|---|
| 1 | 0.02 | 12H, -CH3 |
| 2 | 0.47 | 4H, -CH2- |
| 3 | 1.55 | 4H, -CH2- |
| 4 | 3.37 | 4H, -CH2- |
| 5 | 3.49 | 4H, -CH2- |
| 6 | 1.70 | 4H, -CH2- |
| 7 | 0.85 | 6H, -CH3 |
| 8 | 4.35 | 4H, -CH2- |
| 9 | 4.41 | 4H, -CH2- |
Fig. 9
1H-NMR spectrum of the prepolymer.
Fig. 10
TG (A) and DTG (B) curves of films cured with the prepolymer.
Fig. 11
The viscosity of the prepolymer at different temperatures.
Fig. 12
Heat flow of prepolymer, E-51 and 2021p.
Fig. 13
Total heat of prepolymer, E-51, and 2021p.
Fig. 14
Conversion of a prepolymer, E-51, and 2021p.
Table 6
Mechanical property test results of the prepolymer UV-cured samples.
| Numbering | Tensile strength /MPa | Elastic modulus /MPa | Elongation at break /% |
|---|---|---|---|
| 1 | 26.28 | 3,028.72 | 4.13 |
| 2 | 23.99 | 2,831.19 | 3.89 |
| 3 | 22.97 | 2,730.26 | 4.23 |
| 4 | 27.90 | 3,195.19 | 3.96 |
| 5 | 28.62 | 2,890.40 | 4.26 |
| Average value | 25.95 | 2,935.15 | 4.09 |
| Standard deviation | 2.19 | 161.97 | 0.15 |