Cyclopolymerisation studies: The synand characterisation of selected di-unsaturated momers and a study of their polymerisation.

The literature covering the cyclopolymerisation reaction is briefly surveyed with emphasis on the methods used to determine ring size in cyclopolymers. Part 1 of this thesis describes the synthesis and polymerisation of N,N'-divinylureas of general structure: CH2=CH-N-CO-N-CH=CH2. The cyclic N,N'-divinylureas, 1,3-divinylimidazolid-2-one (R+R=-CE2-CE2-) and 1,3-divinylhexahydropyrimid-2-one (R+R=-CE2-CE2-CH2-), gave insoluble, cross-linked polymers which confirmed the findings of Crawshaw and Jones. The acyclic N,N'-divinylureas, 1,3-diphenyl-1,3-divinylurea (R=R=C6H5) and 1,3-dimethyl-1,3-divinylurea (R=R=CH3), could not be polymerised under a variety of conditions. To explain the failure of the cyclic N,N'-divinylureas to cyclopolymerise, Crawshaw and Jones proposed a continuous coplanar overlap of the pi orbitals of the vinyl and carbonyl groups with p[z] orbitals on the nitrogen atoms. Evidence to support this proposal has been obtained from ultraviolet, n.m.r. and infrared spectroscopy. The failure of the acyclic N,N'-divinylureas to polymerise has also been explained on the basis of this overlap. Addition of a radical initiator to 1,3-diphenyl-1,3-divinylurea produces a resonance stabilised radical which does not homopropagate and which inhibits or retards the polymerisation of other monomers. A study of the copolymerisation behaviour of N,N'-divinylureas supports this proposal. Although 1,3-divinylimidazolid-2-one and 1,3-divinylhexahydropyrimid-2-one form copolymers with ethyl acrylate from which reactivity ratios and Q and e values have been determined, 1,3-diphenyl-1,3-divinylurea inhibits the polymerisation of these N,N'-divinylureas and ethyl acrylate and retards the polymerisation of styrene. For 1,3-dimethyl-1,3-divinylurea it is suggested that conjugation does not permit intramolecular cyclopolymerisation and that a steric effect prevents the intermolocular reaction. A study of the hydrolysis of N,N'-divinylureas to acetaldehyde and the corresponding urea is included. Part 2 describes the synthesis and cyclopolymerisation of divinyl phonylphosphonate and divinyl methylphosphonate. 31P N.m.r. spectroscopy is shown to be able to quantitatively determine phosphorus atoms in different chemical environments and is applied to the determination of five- and/or six-membered rings in the cyclopolymers from divinyl phosphonates. Using this tecnnique poly(divinyl phenylphosphonate) was found to contain both five- and six-membered rings and poly(divinyl methylphosphonate) only six-membered rings. Telomerisation of divinyl phosphonates gave di-adducts rather than cyclic mono-adducts.