A thesis submitted to the University of Durham for the Degree of Doctor of Philosophy
Studies directed towards the step growth photopolymerization of carbonyl compounds
Constantinos Spanomanolis, B.Sc.
Graduate Society (now Ustinov College)
|Non sien le genti, ancor, troppo sicure
a giudicar, si comme quei che stima
le biade in campo pria che sien mature;
ch' io veduto tutto il verno prima
lo prun mostrarsi rigido e feroce,
poscia portar la rosa in su la cima;
e legno vidi gia dritto e veloce
correr lo mar per tutto suo cammino,
perire al fine all'intrar della foce.
|So also let not the people be too sure
in judging, like those that reckon
the corn in the field before it is ripe;
for I have seen the briar first
show all harsh and rigid through the winter
and later bear the rose upon its top;
and once I saw a ship that ran straight and swift
over the sea through all its course
and perish at the last enetering the harbour.
Dante Alighieri, 'La Divina Commedia', Paradiso, Canto XIII, 130-138
This thesis describes some work carried out in the relatively new area of step-growth photopolymerization of carbonyl compounds.
The possibility of extending the photoreductive polymerization of aromatic diketones (leading to the synthesis of polybenzopinacols) to the photochemical synthesis of pentaphenylglycerols and higher analogues was investigated; however examination of the model photochemical reaction between benzophenone and triphenylglycol established that this glycol (and the related 1,2,2,2,-tetraphenylethanol) is not a hydrogen donor for triplet benzophenone.
In an attempt to examine the possibility of extending the photoreductive addition of benzophenone to diphenyl methane to polymer synthesis, m-dibenzoylbenzene and m- and p-dibenzylbenzenes were prepared and characterized.
Irradiation of the diketone in the presence of an equimolar amount of either of the dibenzylbenzenes afforded low molecular weight products, shown by proton and crbon-13 n.m.r. spectroscopy to contain benzopinacol, tetraphenylethane and 1,1,2,2,-tetraphenylethanol type of units, in addition to benzophenone-type carbonyl and benzyl groups. results obtained from the pyrolitic decomposition or treatment with dehydrating agents of one of the products were consistent with tyhe proposed structure.
Irradiation of tere- or iso-phthalaldehyde in the solid state yielded mostly starting materials whereas branched low molecular weight products were obtained from the irradiation of either of these aromatic dialdehydes in the presence of the hydrogen-donating isopropanol.
An investigation on the structure of the 'photopolymer' produced on irradiating benzaldehyde in the liquid phase, by means of conventional spectroscopic analysis did not lead to a convincing structural hypothesis.
'Classical' chemical reactions proved to be more useful in this case; it was thus shown that the 'photopolymer', which has the same elemental composition as benzaldehyde but a molecular weight 9 - 11 times as high, can be acetylated, oxidized and is reactive towards sulphuric acid; it is furthermore stable to irradiation in benzene solution at 300nm in the absence of air and non-photoreducible in isopropanol; it is however reduced by either sodium borohydride or sodium bis(2-methoxyethoxy)-aluminium hydride giving rise to a different structure in each case.
Finally an extension of the Paterno'-Buecchi reaction of perfluoro compounds to polymer synthesis was attempted by examining the cycloaddition of perfluoroglutarylfluoride to two perfluoroolefins under a variety of experimental conditions. This work was largely unsuccessful and the rationalisation of the results obtained will be fouund in the last Chapter of this thesis.
The author is indebted to Dr. W. J. Feast for his continued help and encouragement unfailingly given during the supervision of this work. His patience and understanding, both on the professional and personal level, have been invaluable to the author.
Thank are due to Dr. R. S.Matthews for running n.m.r. spectra, Dr. B. J.Cromarty for translating papers from German, and Drs. G. M. Brooke and C. D. Bartlett for helpful suggestions.
Assistance from members of the technical and laboratory staff is greatly appreciated; in particular assistance from Mrs. S. E. Robson for running i.r. spectra and Mr. D. Hunter for practical advice is gratefully acknowledged.
Discussions with the other members of the Reasearch Laboratory '25' have been particularly helpful and their collaboration is also appreciated.
The author thanks the European Research Office of the U. S. Army for the award of a maintenance grant and Mr. Apostolos Spanomanolis of 'Christos Spanomanolis Sons', Athens, Greece, for some financial support.
Finally, thanks are due to Mrs. E. Duddy and Miss A. Laing for typing this thesis, and Mr. M. Strange for helping with some of the drawings.
The work described in this thesis was carried out in the Chemistry Laboratories of the University of Durham between September 1975 and August 1978. This work has not been submitted for any other degree and is the original work of the author, except where acknowledged by reference.