The vinylic polymerization of norbornenes upon catalysis with Pd2' complexes with norbornylnitrile as ligands is reported. The polynorbornenes (a,,, = lo6) display a set of unique properties including a dense packing in the amorphous state, high glass transition temperatures, large refractive index, low birefringence and significant brittleness. To test the concept that these properties can be traced back to the conformational constraints of the polymer chains, we performed ab initio calculations, semi-empirical quantum mechanical calculations and force-field calculations employing a force field developed by us for polynorbornenes.

The vinylic polymerization of 5-norbornene-2-carboxylic esters with different palladium catalysts to polymers of high molecular weights is reported. Computer simulations based on a force field approach show that these polymers display a rigid statistical chain conformation and are thus a further example of rotationally strongly constrained polymers. The polymers are soluble in a variety of solvents despite their rigidity, they are amorphous, possess glass transition temperatures well above 250°C, and have a high packing density. The dipoles located in the lateral groups perform a secondary relaxation process similar to the case of flexible or rigid rod-like polymers containing ester groups. Acta Polymer., 48,385-391 Q VCH Verlagsgesellschaft mbH, D-69451 Weinheim 1997 0323-7648/97/0808-0385$17.50+.50/0 385

SUMMARY: The contribution reports on the vinylic polymerisation of exo N-o/m/p tolyl (Io/Im/Ip)-nadimides using a Pd(II) catalyst, on computer simulations on the chain conformation and dynamics as well as on the structure and glass transition in the condensed state. The poly(norbornene imide)s are densely coiled yet highly rigid chain molecules. The energy barriers are sufficiently high to prevent rotational motions for temperatures up to 380 8C. This rigidity causes the formation of a glassy state and a glass transition temperature of as high as 330 8C.

SUMMARY Polynorbomene is characterized by the presence of large rotational barriers separating different rotational isomeric states. We have investigated the effect of these rotational constraints on conformational and dynamical properties in the condensed state using force field simulations. The chain is found to be a rigid coil with dimensions similar to the case of the isolated chains and the fluctuations of the chain dimensions are reduced compared to those found for isolated chains. An interesting result is that calculations based on an amorphous cell predict the occurrence of a glass transition temperature -in agreement with experimental results -at a temperature where the chain molecules are still rigid.

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