Precise control over monomer sequence in synthetic polymers remains a central challenge in polymer chemistry, with significant implications for materials design and controlled degradation. Here, we report a modular and efficient strategy for synthesizing ABAC-type periodic terpolymers by integrating reversible addition–fragmentation chain transfer single-unit monomer insertion (RAFT-SUMI) with RAFT step-growth polymerization. Sequence-regulated oligomers are first constructed via RAFT-SUMI using bifunctional RAFT agents and vinyl monomers, then employed as bifunctional RAFT agents for step-growth polymerization with complementary vinyl monomers. The method enables precise control over polymer sequence and architecture, affording terpolymers with tunable molecular weights and thermal properties. A broad library of ABAC-type terpolymers was synthesized, exhibiting glass transition temperatures (Tg) from −28.75 to 79.75 °C and decomposition temperatures (Td) from 194.9 to 243.64 °C. Incorporation of disulfide linkages into the polymer backbone further enabled selective degradation in response to chemical stimuli, confirming the periodic nature of the sequence. This work establishes a generalizable platform for constructing precision macromolecules with programmable functionality, offering broad potential for applications in degradable materials and advanced polymer systems.
The development of biorenewable polyhydroxyalkanoate (PHA) chemistry has generated interest in crotonate-based monomers as versatile building blocks. Crotonates can be obtained through the pyrolysis of PHAs, offering both a sustainable end-of-life pathway for PHAs and a renewable route to crotonate monomers. This study presents a new polyaddition-type step-growth polymerization of dicrotonates in which alkene-functionalized polyesters are synthesized using potassium tert-butoxide as a simple base catalyst. The reaction proceeds rapidly at room temperature, achieving >99% conversion within seconds and requiring no byproduct removal. The properties of the resulting polyesters can be tuned via the choice of bridging diol, and the materials are degradable by hydrolysis. The polymers reported herein are soft, amorphous solids with predominantly cyclic architectures under standard conditions, while linear analogs can be accessed through a chain-end-capping strategy. The work presented herein bridges key principles of polymer sustainability─including biorenewability of feedstocks, energy-efficient synthesis, and degradable end-of-life pathways─with practical considerations essential for real-world application, such as operational simplicity, scalability, cost-effectiveness, and supply chain accessibility.
Poly(vinyl alcohol) (PVA) is widely employed for hydrogel fabrication due to its ability to form stable, physically or chemically cross-linked three-dimensional networks. Among production methods, the freezing–thaw (F–T) technique stands out for its simplicity and effectiveness. This study presents a straightforward methodology for preparing functional PVA hydrogels in aqueous media by blending PVA with a crystallizable hexadecyl alkylamine (C16). Incorporating small amounts of hydrophobic, amphiphilic hexadecylamine into PVA hydrogels via freezing–thaw blending significantly alters crystallization and network structure, enabling gel formation in water without surfactants, solvents, or cross-linkers. C16 enhances phase separation and promotes PVA crystalline domains while remaining amorphous. The resulting PVA/C16 hydrogels exhibit enhanced thermomechanical properties, demonstrating additional functionalities such as self-healing and improved adhesion to polar surfaces. This crystallization-driven gelation via immiscible blending offers a scalable strategy with potential in wearable electronics, soft robotics, and biomedical devices.
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