Poly(butylene 1,4‐cyclohexanedicarboxylate) (PBCHD) is an environmentally friendly material, as it can be obtained from biomass (although nowadays it is prepared from petroleum resources) and is potentially biodegradable. Moreover, the aliphatic rings along the chains lend interesting characteristics, for example good mechanical properties and resistance to weather for outdoor applications. As many properties, such as biodegradability, strongly depend on crystallinity, a study of the crystallizability of PBCHDs is very meaningful. Equilibrium melting temperatures and crystallization rates are strongly affected by the cis/trans ratio of the 1,4‐cyclohexylene units. Indeed, only the trans isomer can form crystals, whereas the cis isomer is fully excluded from the crystalline phase. All thermal data can be well understood by considering PBCHD as a random copolymer with crystallizable (trans isomer) and noncrystallizable (cis isomer) components, which only differ for the stereochemistry of the aliphatic rings. magnified image

In the field of aliphatic polyesters there is a great interest in building novel macromolecular structures that may effectively feature the required properties for specific applications. For this reason, it is extremely important to understand the correlations between chemical structure and final performance. Monomers based on the 1,4‐cyclohexylene unit are interesting as they are potentially bio‐based and rigid enough to improve glass transition and melting temperatures. The present paper describes the preparation of samples of poly(1,4‐cyclohexylenedimethylene adipate), characterized by different cis/trans isomeric ratio of the cyclic units, the analysis of their thermal properties and the comparison with the properties of similar polymers such as poly(butylene adipate), poly(butylene‐1,4‐cyclohexanedicarboxylate) and poly(1,4‐cyclohexylenedimethylene‐1,4‐cyclohexanedicarboxylate). The effect of the rigidity and of the stereochemistry of the 1,4‐cyclohexylene unit on the thermal properties was analysed. Such an effect reaches its maximum level when the cyclic‐containing monomers are the diacid or the diester and when the trans isomers predominate. Starting from such a result, the combination of specific cyclic building blocks with the correct cis/trans ratio makes it possible to build macromolecular structures with the required final properties.

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