Photocycloaddition in solid poly(vinyl cinnamate). The photoreactive polymer matrix as an ensemble of chromophore sites

Egerton, Peter L.; Pitts, E.; Reiser, Arnost

doi:10.1021/ma50002a019

Cited by 209 publications

(113 citation statements)

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“…12 We recently reported kinetic parameters during the simultaneous occurrence of intraand intermolecular photocrosslinking in polymers containing cinnamoyl groups in dilute solution. 14 -16 The quantum yields for intramolecular crosslink formation increase linearly with increasing cinnamoyl groups in a polymer.…”

mentioning

confidence: 99%

Effect of Intramolecular Crosslinks on Microgel and Macrogel Formation by Photocrosslinking Reaction in Solution

Shindo

Sugimura

Horie

et al. 1990

Polym J

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ABSTRACT:Microgel and macrogel formation during the photodimerization of cinnamoyl groups in polymer chains has been investigated through analysis of intramolecular crosslinks using spectrophotometric and light scattering measurements. The form of gels depended particularly on the amount of cinnamoyloxyethyl methacrylate (CEMA) in copoly (CEMNMMA). For CEMA = 12 mo!% copolymer, micro gels were formed in the early stage of reaction, and finally homogeneous macrogels in appearance were formed. The resulting microgel for CEMA = 26 mo!% copolymer was composed of networks having the number of intramolecular crosslinked cinnamoyl groups, n'"'" = 1870 in 3400 units of cinnamoyl groups per polymer chain. At the onset of gelation, the volume of polymer coils due to intramolecular crosslinks became 1/350-1/10 the volume of the corresponding linear polymer of the same molecular weight. The extent of intra-and intermolecular crosslinks and contraction of polymer coils due to intramolecular crosslinks were estimated in the process of gel formation.KEY WORDS Microgel / Macrogel / Intramolecular Crosslink / Photocrosslinking / Photodimerization / Cinnamoyl Group / Contraction of Polymer Coil / Light Scattering / Onset of Gelation / The formation of a three-dimensional network of polymer molecules has been investigated by many authors. 1 -io When polymer molecules are crosslinked in solution, either during polymerization or by polymer reactions, both intra-and intermolecular crosslinks can be formed. In the radical copolymerization of styrene and divinylbenzene in solution, the extent of competition between intra-and intermolecular crosslinking and intramolecular cyclization between adjacent units has been discussed. 2 · 3 • 5 White et al. 2 have reportd that the probability of intramolecular cyclization is rather high, whereby the number of elastically effective network chains is reduced. Horie et al. 3 have also revealed three kinds of modes for crosslinking from an experimental study on the crosslinked copolymerization of methylmethacrylate (MMA) with ethylene dimethacrylate (EDMA) in bulk and in toluene. It had been shown that crosslinked copolymerization depends on the initial composition of monomers and concentration in toluene, and intramolecular crosslinking between nonadjacent units and the formation of microgels are important characteristics for copolymerization with higher divinyl contents. Matsumoto et al. 4 • 9 have examined the gelation for the polymerization of diallyl esters of aromatic dicarboxylic acids and discussed the results according to Gordon's theory. 1 They concluded that the intramolecular chain transfer reaction plays an important role during polymerization. The gel formation due to photogenerPolym.

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confidence: 99%

Effect of Intramolecular Crosslinks on Microgel and Macrogel Formation by Photocrosslinking Reaction in Solution

Shindo

Sugimura

Horie

et al. 1990

Polym J

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“…It can be considered three possible mechanisms for this reorientation of LC molecules on the rubbed PVCi film exposed to high dosage of RP-UV light; one is the interaction of LC molecules with the backbones of PVCi molecules, and the others are the interactions of LC molecules with the groove formed on the rubbed PVCi films and/or the photo-dimerized side chains. It was reported [19] that there are eleven stereoisomers of the photo-dimerized side chains, and the dimerization process described in Fig. 1 does not occur mainly.…”

Section: Resultsmentioning

confidence: 93%

Mechanism of Photo-Induced Liquid Crystal Alignment on Poly(vinyl cinnamate) Surface.

Shinmoto

Nakamura

et al. 1997

J. Photopol. Sci. Technol.

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The photopolymer material of polyvinyl cinnamate) (PVCi) has been used to align liquid crystal molecules using linearly-polarized UV light, and the LC alignment mechanism on the films has been investigated. Comparing the LC alignment on rubbed PVCi films with that on UV-exposed PVCi film, it is shown that the side chains of PVCi molecules strongly interact with the LC molecules on the PVCi films and thus the alignment mechanism on linearly-polarized UV-exposed PVCi films is due to the anisotropic van der Waals interaction between LC molecules and optically-anisotropic PVCi films arising from the photo-induced anisotropic side chain distribution on the films. We also study the thermal stability of UVexposed PVCi films, and clarify the improvement of the thermal stability with increasing UV exposure energy.

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“…The solution containing benzyl 9-anthracenecarboxylate (2.0 x 10-4 mol dm- 3 ) and benzyl eosinate (l.Ox 10-5 moldm-3 ) in a pyrex cell was degassed and sealed off under the same conditions. …”

Section: Methodsmentioning

confidence: 99%

Fluorescence Study on the Dynamics and Structure of Polymer Chain I. Intramacromolecular Photo-crosslinking Reaction of a Polymer Containing Anthryl and Eosinyl Moieties in Dilute Solution

Torii

Ushiki

Horie

1992

Polym J

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ABSTRACT:A photo-crosslinkable polymer with pendant anthryl and eosinyl m01etJes attached to its side chains was synthesized. Dilute DMF (N,N-dimethyl formamide) solutions of the polymer were UV-irradiated to induce intramacromolecular photo-crosslinking reaction under degassed conditions. Decrease in anthryl moiety based on photo-dimerization between anthryl moieties during the UV-irradiation was evaluated from the change in absorption spectra. Change in the dimensions of the polymer coil induced by the reaction was studied by GPC. Parameters for polymer chain dynamics were studied in the course of the intramacromolecular crosslinking reaction resulting in shrinkage of the polymer coil. The time-conversion curve of the photodimerization between anthryl moieties showed that the photo-crosslinking reaction consists of two stages. The mobility of polymer chain segments decreased gradually in the initial stage and deceases rapidly in the later stage. Radius of gyration of the polymer coil and the rotational mobility of side chain decreased rapidly only in the later stage. Three possible models for the reaction are discussed in order to explain the results. The short range reaction model is most suitable model for the intramacromolecular crosslinking reaction. In the initial stage crosslinks are formed between nearest-neighbor side chains; in the later stage shrinkage of the polymer coil occurs due to formation of crosslinks between far-apart side chains which remained unreacted in the initial stage.

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Photocycloaddition in solid poly(vinyl cinnamate). The photoreactive polymer matrix as an ensemble of chromophore sites

Cited by 209 publications

References 4 publications

Effect of Intramolecular Crosslinks on Microgel and Macrogel Formation by Photocrosslinking Reaction in Solution

Effect of Intramolecular Crosslinks on Microgel and Macrogel Formation by Photocrosslinking Reaction in Solution

Mechanism of Photo-Induced Liquid Crystal Alignment on Poly(vinyl cinnamate) Surface.

Fluorescence Study on the Dynamics and Structure of Polymer Chain I. Intramacromolecular Photo-crosslinking Reaction of a Polymer Containing Anthryl and Eosinyl Moieties in Dilute Solution

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