Abstract
UV-induced matrix cross-linking is the method of choice to form polymer-dispersed liquid crystals (PDLCs). In this paper, real-time FTIR spectroscopy is applied to study the curing of a model system - a thiolene-chemistry-based prepolymer (NOA65) and its mixtures with liquid crystals. Curing reactions of NOA65 were examined as a function of the film thickness, temperature, and liquid-crystal content. While there was little dependence of the curing behavior on the thickness of the film, the effect of temperature was strong. Curing rates exhibit a maximum around 325 K, while conversions reach a plateau about 20 K higher. The effect of liquid-crystal addition reveals a depression in the conversion. However, compared to the neat matrix, the final conversion was found to be significantly lower only for phase-separating concentrations. The rate of reaction decreased, and the induction period for the onset of polymerizing reactions increased with increasing liquid-crystal concentration. Real-time FTIR spectroscopy is shown to be a viable tool to monitor PDLC formation to optimize curing conditions and characterize the chemical state of components. This provides a basis to allow the morphological structure to be related to observed properties of the film.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 8982-8988 |
| Number of pages | 7 |
| Journal | Macromolecules |
| Volume | 32 |
| Issue number | 26 |
| DOIs | |
| State | Published - Dec 28 1999 |
| Externally published | Yes |
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ASJC Scopus subject areas
- Materials Chemistry
Cite this
Studying polymer-dispersed liquid-crystal formation by FTIR spectroscopy. 1. Monitoring curing reactions. / Bhargava, Rohit; Wang, Shi Qing; Koenig, Jack L.
In: Macromolecules, Vol. 32, No. 26, 28.12.1999, p. 8982-8988.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Studying polymer-dispersed liquid-crystal formation by FTIR spectroscopy. 1. Monitoring curing reactions
AU - Bhargava, Rohit
AU - Wang, Shi Qing
AU - Koenig, Jack L.
PY - 1999/12/28
Y1 - 1999/12/28
N2 - UV-induced matrix cross-linking is the method of choice to form polymer-dispersed liquid crystals (PDLCs). In this paper, real-time FTIR spectroscopy is applied to study the curing of a model system - a thiolene-chemistry-based prepolymer (NOA65) and its mixtures with liquid crystals. Curing reactions of NOA65 were examined as a function of the film thickness, temperature, and liquid-crystal content. While there was little dependence of the curing behavior on the thickness of the film, the effect of temperature was strong. Curing rates exhibit a maximum around 325 K, while conversions reach a plateau about 20 K higher. The effect of liquid-crystal addition reveals a depression in the conversion. However, compared to the neat matrix, the final conversion was found to be significantly lower only for phase-separating concentrations. The rate of reaction decreased, and the induction period for the onset of polymerizing reactions increased with increasing liquid-crystal concentration. Real-time FTIR spectroscopy is shown to be a viable tool to monitor PDLC formation to optimize curing conditions and characterize the chemical state of components. This provides a basis to allow the morphological structure to be related to observed properties of the film.
AB - UV-induced matrix cross-linking is the method of choice to form polymer-dispersed liquid crystals (PDLCs). In this paper, real-time FTIR spectroscopy is applied to study the curing of a model system - a thiolene-chemistry-based prepolymer (NOA65) and its mixtures with liquid crystals. Curing reactions of NOA65 were examined as a function of the film thickness, temperature, and liquid-crystal content. While there was little dependence of the curing behavior on the thickness of the film, the effect of temperature was strong. Curing rates exhibit a maximum around 325 K, while conversions reach a plateau about 20 K higher. The effect of liquid-crystal addition reveals a depression in the conversion. However, compared to the neat matrix, the final conversion was found to be significantly lower only for phase-separating concentrations. The rate of reaction decreased, and the induction period for the onset of polymerizing reactions increased with increasing liquid-crystal concentration. Real-time FTIR spectroscopy is shown to be a viable tool to monitor PDLC formation to optimize curing conditions and characterize the chemical state of components. This provides a basis to allow the morphological structure to be related to observed properties of the film.
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U2 - 10.1021/ma990707+
DO - 10.1021/ma990707+
M3 - Article
AN - SCOPUS:12944289749
VL - 32
SP - 8982
EP - 8988
JO - Macromolecules
JF - Macromolecules
SN - 0024-9297
IS - 26
ER -