AbstractThe extrapolated melting point of native 1,4‐trans‐isotactic‐polypentadiene obtained by inclusion polymerization in pre‐irradiated perhydrotriphenylene is 104°C, 10 K higher than that of a long‐annealed conventional polymer. The WAXS spectrum corresponds to that of the already known paracrystalline structure; this notwithstanding, its heat of melting is 20–70% higher than that of polypentadiene crystallized from solution or from the melt. The native polymer shows noteworthy superheating phenomena and is not able to induce crystallization of high‐melting crystals from the melt. This behaviour is consistent with that predicted for extended‐chain polymeric crystals. This conclusion is supported by the absence of definite peaks in the SAXS spectrum of th