The intram olecularly crosslinked polystyrene molecules, prepared as in p a rt I of this series, were exam ined by th e techniques of light scattering, osmom etry, viscom etry, an d gel perm eation chrom atography. Their molecular masses an d molecular mass distribution rem ained constant over all the stages of the reaction radii of gyration were determ ined and th e results com pared w ith those predicted in p a rt I I of this series. I n t r o d u c t i o n This paper is concerned with an

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... rimental investigation, on the polymers described in part I of this series, of some of the consequences of a general theory of polymerized materials developed by one of the authors. This theory is extended in p art I I of this series to the particular case of the dimensions of an intramolecularly crosslinked polymer molecule, th a t is, a molecule which contains links between certain segments of the molecule and other segments of the same polymer molecule. The basic theory (Edwards & Freed 1970) deals with a very long threadlike molecule having zero cross-section and no specific chemical structure. The chain has permanent internal connexions (crosslinks) a t random points along its contour length. A variational calculation is made on the potential due to the crosslinks. The relation between the unperturbed mean-square radius of gyration (R q) of a coil containing m randomly placed intramolecular crosslinks and the unperturbed mean square radius of gyration of the original free chain (R q) 0 is found to be In principle this theoretical relation can be checked directly by light scattering measurements under theta conditions on a suitably crosslinked polymer sample. Unless, however, the molecular weight of the original uncrosslinked sample of poly mer is extremely large, the radius of gyration of the intramolecularly crosslinked