Photopolymerization chemically induced

In this review article we present some typical examples showing how effective RTIR spectroscopy proved to be to evaluate the important kinetic parameters of photoinitiated radical and cationic polymerizations, and to assess the influence of some chemical and physical parameters on both the rate and the extent of the light-induced curing reactions. The photopolymerization of different types of monomer mixtures will also be examined, as RTIR spectroscopy is a unique tool to follow the kinetics of... 

The one- and two-photon excited fluorescence property and crystal structure of a substituted stilbene-type compound frans-4-diethylamino-4 -bromostilbene (DEARS) has been reported [17]. Results indicate that this compound has a strong two-photon-exdted blue fluorescence at 440 nm when the 700 nm laser is used as the pump source. The one- and two-photon absorption and fluorescence properties of a free radical photopolymerization initiator, ( , )-4- 2-[p -(]yf,N-di-w-butylamino)stil-ben-p-yl]vinyl pyridine (Figure 3.8), in various solvents have been investigated [18]. The dye has a moderate two-photon absorption cross section of = 0.91 x 10 cm s/photon at 532 nm. This compound showed a strong two-photon-induced blue fluorescence of432 nm when pumped with 800 nm laser irradiation. Quantum chemical calculation indicated that the new initiator possesses a large delocalized... 

Novel polymer systems with much enhanced TPA initiators have been synthesized. However, it is still attractive to use well-known systems that were developed for conventional UV polymerization due to their excellent chemical, physical, and mechanical properties. Initiators in these resins generally have small TPA cross-sections, which require very high laser pulse energy for two-photon use. A strategy for circumventing this situation is to induce photopolymerization not by direct TPA of initiators, but by TPA-induced up-conversion fluorescence. An efficient fluorophore that emits at blue or shorter wavelengths was doped into resin. By TPA, the excited fluorescence polymerizes the resin by a single photon process. Since the fluorescence was three-dimensionally confined at the focal spot, the polymerization was also restrained to occur at this volume. 

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