The effect of terminal alkyl chains on hyperbranched polyesters based on 2,2‐bis(hydroxymethyl)propionic acid

A hyperbranched hydroxyfunctional polyester based on 2,2‐bis(hydroxymethyl)propionic acid as AB2‐monomer and a tetrafunctional polyol as core was end‐capped with five different alkylacyl chlorides. Alkyl chain lengths ranging from three to sixteen carbons were used. Short alkyl chains (3–6 carbons) decrease the glass transition temperature from around 30°C for the hydroxyterminated polyester to temperatures well below zero. With a sufficiently long alkyl chain (12–16 carbons) the polymers tend to crystallize. The polyesters with C16‐chains as terminal groups exhibit several different crystalline phases as revealed by differential scanning calorimetry. From X‐ray data it was possible to suggest that the crystallization for the C16‐terminated samples occurs in a non‐interpenetrating fashion for the larger sample and in an interpenetrating way for the smaller polymers.