Abstract: A shaped polyphosphazene article having a modified surface portion thereof and exhibiting a desired property and/or performance comprises a polyphosphazene polymer having at least 50 molar % or more of repeating units of the formula (I): ##STR1## wherein R.sup.1 and R.sup.2 in the first and second side chains --OR.sup.1 and --OR.sup.2 respectively represent, independently from each other, an aliphatic, cycloaliphatic or aromatic radical, and having at least a portion of a surface portion thereof in which at least 5 molar % of the first and second side chains are converted to one or more types of third side chains --OR.sup.3 wherein R.sup.3 represents an aliphatic, cycloaliphatic or aromatic radical and which are different from --OR.sup.1 and --OR.sup.2.

Abstract: A support convenient for preparing a printing plate in situ using a liquid photosensitive resin of an unsaturated polyurethane resin is disclosed. This support consists of a base plate and coated thereon a layer of a composition consisting of a mercapto-containing ester obtained by polycondensing a thiocarboxylic acid or thioalcohol with a polyglycol or polycarboxylic acid or an aromatic tertiary amine and a polymer binder. The support of this invention, which has a broadened base of a sectionally trapezoidal configuration, provides a relief image that is firmly adhered to the support.