Control of Crystallinity and Stereocomplexation of Synthetic Carbohydrate Polymers from d‐ and l‐Xylose

Manipulating the stereochemistry of polymers is a powerful method to alter their physical properties. Despite the chirality of monosaccharides, reports on the impact of stereochemistry in natural polysaccharides and synthetic carbohydrate polymers remain absent. Herein, we report the cocrystallisation of regio‐ and stereoregular polyethers derived from d‐ and l‐xylose, leading to enhanced thermal properties compared to the enantiopure polymers. To the best of our knowledge, this is the first example of a stereocomplex between carbohydrate polymers of opposite chirality. In contrast, atactic polymers obtained from a racemic mixture of monomers are amorphous. We also show that the polymer hydroxyl groups are amenable to post‐polymerisation functionalization. These strategies afford a family of carbohydrate polyethers, the physical and chemical properties of which can both be controlled, and which opens new possibilities for polysaccharide mimics in biomedical applications or as advanced materials. Synthetic carbohydrate polyethers, which are polysaccharide mimics, are synthesised by regioregular anionic ring‐opening polymerisation of oxetanes produced from d‐ or l‐xylose. By exploiting the chirality of xylose and varying stereochemical composition, the crystallinity of the resulting materials can be controlled. Mixing together homochiral polymers of opposite configuration results in a stereocomplex with enhanced thermal properties.