ABSTRACT Poly( ε ‐caprolactone)‐ b ‐polysarcosine (PCL‐ b ‐PSar) is an amphiphilic block copolymer (BCP) with excellent biocompatibility, yet its crystallization‐driven self‐assembly (CDSA) in alcohols typically produces multilayer lamellae containing screw dislocations. To suppress these defects and obtain uniform monolayer lamellae, the effects of a series of hydrogen‐bond donor additives on the CDSA of PCL‐ b ‐PSar in alcohols are systematically investigated. The results demonstrate that acidic additives, such as acetic acid, effectively suppress screw dislocations, yielding elongated truncated lozenge‐shaped monolayer lamellae. It is proposed that the hydrogen‐bonding interactions between acids and both blocks of PCL‐ b ‐PSar play a key role in modulating the CDSA. Acid–PSar interactions enhance the solubility and local chain deformability of PSar, thereby releasing interglobular repulsion, while acid–PCL interactions decelerate the crystallization of PCL, facilitating regular rearrangement of the unimers at the growth front. These two effects synergically promote ordered crystallization of PCL‐ b ‐PSar and suppress screw dislocation formation during crystal growth. This study provides new insights into the acid‐mediated CDSA of PCL‐ b ‐PSar and establishes a viable strategy for controlling screw dislocations in polymer lamellae.
Li et al. (2026) studied this question.