Synthesis and Self-Assembly of Poly(N-Vinylcaprolactam)-b-Poly(epsilon-Caprolactone) Block Copolymers via the Combination of RAFT/MADIX and Ring-Opening Polymerizations

Author(s)

Moraes, Rodolfo M. ^[1] ; Carvalho, Layde T. ^[1] ; Alves, Gizelda M. ^[1] ; Medeiros, Simone F. ^[1] ; Bourgeat-Lami, Elodie ^[2] ; Santos, Amilton M. ^[1]

Affiliation

^[1] Univ Sao Paulo, Engn Sch Lorena, Dept Chem Engn, EEL USP, Lab Polymers, Estr Municipal do Campinho S-N, POB 116, BR-12602810 Lorena, SP - Brazil

^[2] Univ Claude Bernard Lyon 1, Univ Lyon, CPE Lyon, CNRS, UMR 5265, Chem Catalysis Polymers & Proc C2P2, 43 Bvd 11 Novembre 1918, F-69616 Villeurbanne - France

• Document type: Journal article
• Source: POLYMERS; v. 12, n. 6 JUN 2020.
• Web of Science Citations: 0

Abstract

Well-defined amphiphilic, biocompatible and partially biodegradable, thermo-responsive poly(N-vinylcaprolactam)-b-poly(epsilon-caprolactone) (PNVCL-b-PCL) block copolymers were synthesized by combining reversible addition-fragmentation chain transfer (RAFT) and ring-opening polymerizations (ROP). Poly(N-vinylcaprolactam) containing xanthate and hydroxyl end groups (X-PNVCL-OH) was first synthesized by RAFT/macromolecular design by the interchange of xanthates (RAFT/MADIX) polymerization of NVCL mediated by a chain transfer agent containing a hydroxyl function. The xanthate-end group was then removed from PNVCL by a radical-induced process. Finally, the hydroxyl end-capped PNVCL homopolymer was used as a macroinitiator in the ROP of epsilon-caprolactone (epsilon-CL) to obtain PNVCL-b-PCL block copolymers. These (co)polymers were characterized by Size Exclusion Chromatography (SEC), Fourier-Transform Infrared spectroscopy (FTIR), Proton Nuclear Magnetic Resonance spectroscopy (H-1 NMR), UV-vis and Differential Scanning Calorimetry (DSC) measurements. The critical micelle concentration (CMC) of the block copolymers in aqueous solution measured by the fluorescence probe technique decreased with increasing the length of the hydrophobic block. However, dynamic light scattering (DLS) demonstrated that the size of the micelles increased with increasing the proportion of hydrophobic segments. The morphology observed by cryo-TEM demonstrated that the micelles have a pointed-oval-shape. UV-vis and DLS analyses showed that these block copolymers have a temperature-responsive behavior with a lower critical solution temperature (LCST) that could be tuned by varying the block copolymer composition. (AU)

• FAPESP's process: 13/03355-4 - Synthesis of biodegradable/biocompatible block copolymers for obtaining polymeric micro-and nanoparticles for controlled drug release
• Grantee: Rodolfo Minto de Moraes
• Support Opportunities: Scholarships in Brazil - Doctorate (Direct)