The precise control of monomer sequence in copolymer chains is essential for tailoring advanced functional properties, particularly in stimuli-responsive materials. This study presents a novel and efficient approach to achieve sequence-controlled copolymerization using 2,5-dimethylfuran/acrylonitrile (MFAN) as a thermally activated latent monomer. The strategy leverages the reversible retro Diels–Alder (rD-A) reaction, where the exo-MFAN adduct remains inert at low temperatures but undergoes selective cleavage at elevated temperatures to release free acrylonitrile (AN) in situ during RAFT polymerization.

The use of 2,5-dimethylfuran instead of unsubstituted furan provides significant advantages: higher thermal stability, reduced radical side reactions, and improved process safety due to its elevated boiling point (93 °C). The exo-isomer of MFAN was selected as the optimal latent monomer based on its faster rD-A kinetics at 75 °C compared to the endo-isomer, enabling timely AN release without compromising chain-end fidelity. This temperature-dependent activation allows for noninvasive, real-time regulation of the instantaneous AN concentration—key to achieving controlled sequence architecture.134678-17-4 medchemexpress

By programming distinct temperature steps during polymerization, a variety of sequence-defined structures were synthesized.2627-69-2 References For instance, a two-stage protocol—40 °C followed by 75 °C—enabled the formation of tapered copolymers with gradual transition from low-AN to high-AN content. When applied to methyl methacrylate (MMA), styrene (St), butyl acrylate (BA), N,N-dimethylacrylamide (DMAM), and N-isopropylacrylamide (NIPAM), the method successfully produced well-defined gradient and di-block copolymers.PMID:30335282 MALDI-TOF mass spectrometry confirmed the presence of target chain-end structures, while SEC analysis revealed low dispersity, indicating excellent livingness and minimal chain transfer.

The most compelling insight emerged from the investigation of thermo-responsivity in poly(NIPAM-co-AN) systems. Polymers with an average distribution of AN units exhibited significantly sharper phase transitions and higher thermal sensitivity compared to those with blocky or clustered sequences. This enhanced responsiveness is attributed to more uniform hydrophobic/hydrophilic balance along the chain, promoting cooperative hydration and dehydration dynamics. In particular, a polymer synthesized under a 75 °C → 25 °C → 75 °C cycling protocol showed near-homogeneous AN distribution and the most sensitive LCST behavior.

This work establishes a versatile, scalable, and highly programmable platform for the synthesis of sequence-controlled acrylonitrile-containing copolymers. The latent monomer concept, combined with simple temperature modulation, offers a powerful alternative to complex catalyst-based strategies. It not only expands the toolbox of sequence control in radical polymerization but also deepens the understanding of how molecular architecture governs macroscopic functionality. These findings lay a strong foundation for next-generation smart materials in biomedical engineering, responsive coatings, and adaptive soft devices.MedChemExpress (MCE) offers a wide range of high-quality research chemicals and biochemicals (novel life-science reagents, reference compounds and natural compounds) for scientific use. We have professionally experienced and friendly staff to meet your needs. We are a competent and trustworthy partner for your research and scientific projects.Related websites: https://www.medchemexpress.com