Polymerization, torsional flexibility

A rubber or elastomer is a polymer with viscoelasticity [1-3], Since rubbers are amorphous polymers above the glass transition temperature, considerable segmental motion is possible, making them relatively soft and deformable, with better elongation, compression, and torsional properties than other polymeric materials. Elastomers and rubbers thus come back fairly close to their original size and shape after the stress is released. The primary uses for these materials include tires, hoses, seals, adhesives, and molded flexible parts, among many others. 

Poly(heterophosphazene)s whose backbones comprise phosphoms, nitrogen, and another element - carbon or sulfur -were also synthesized. " In poly(carbophosphazene)s (poly-114), every third phosphoms atom is replaced by carbon. Poly-114 obtained in the thermal polymerization of a cyclic carbophosphazene was further transformed into white, solid, hydrolytically stable poly((aryloxy)carbophosphazene) (stmcture 115 Af -lO ). The polymer backbone in stmcture 115 was less flexible than in classical polyphosphazenes. The reaction of poly-114 with alkylamines was also studied. Poly (carbophosphazene) s have higher glass transition temperatures than their classical polyphosphazene counterparts with the same side groups. The increased stiffness of the carbophosphazene backbone is attributed to the high torsional barrier of the organic C = N n-bonds compared to the low barrier of the P = N n-bonds. ... 

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