研究目的
To analyze the network structures in thiol-ene UV curing resins using reworkable resins and investigate the effects of thiol functionality, functional ratios, conversions, and curing atmosphere on chain lengths.
研究成果
The network structures in thiol-ene UV curing resins are strongly influenced by crosslinking conditions. Degraded samples have molecular weights between 250 and 2700, with chain lengths proportional to (meth)acrylate concentration. High functionality thiols show lower reactivity due to steric hindrance. Reactive diluents enhance reactivity and increase chain length. Polydispersity values are relatively low (1.3–1.7).
研究不足
The molecular weights obtained from SEC do not correspond to exact values due to differences in hydrodynamic volumes. The study is qualitative, and exact mass relationships were not successfully determined using MALDI-TOF or GC mass spectroscopy.
1:Experimental Design and Method Selection:
The study involved UV curing of mixtures containing (meth)acrylates, thiol compounds, a photoradical initiator (DMPA), and a photoacid generator (DITF) by irradiation at 365 nm, followed by degradation via irradiation at 254 nm and heating. Analysis was performed using SEC and 1H NMR after methylation.
2:Sample Selection and Data Sources:
Samples were prepared with specific formulations of reworkable monomers (DHDA, DHDMA), thiols (BDMB, TAMB, PEMB), and other chemicals.
3:List of Experimental Equipment and Materials:
Equipment included UV-DSC system, mercury-xenon lamp, xenon lamp, SEC system, NMR spectrometer, UV-vis spectrometer, photo-DSC, Raman spectrometer. Materials included DMPA, DITF, trimethylsilyldiazomethane, BzA, DHDA, DHDMA, BDMB, TAMB, PEMB.
4:Experimental Procedures and Operational Workflow:
Mixtures were irradiated at 365 nm in air or N2, then irradiated at 254 nm and baked at 160°C. Insoluble fractions were determined, samples were methylated, and analyzed by SEC and NMR.
5:Data Analysis Methods:
Molecular weights (Mw, Mn, Mp) and polydispersity were calculated from SEC data. Chain lengths were determined from NMR peak integrations.
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UV-DSC system
Shimadzu UV-DSC system
Shimadzu
Used for photo-differential scanning calorimetry to analyze reaction rates of samples.
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mercury-xenon lamp
LIGHTNINGCURE LC8
Hamamatsu Photonics
Light source for irradiation at 365 nm in UV curing.
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xenon lamp
MAX-301
Asahi Spectra
Light source for irradiation at 254 nm in degradation step.
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UV-vis spectrometer
UV-2400 PC
Shimadzu
Characterizes transparency of UV-cured samples.
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Raman spectrometer
RMP-315
JASCO Corporation
Analyzes conversion of thiol and (meth)acryl functions.
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SEC system
PU-2080
JASCO Corporation
Measures molecular weights of degraded samples.
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NMR spectrometer
ECX-400
JEOL Ltd.
Analyzes chain lengths of degraded samples via 1H NMR.
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light intensity meter
UV-M02
ORC Manufacturing Co., Ltd.
Measures intensity of light during irradiation.
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