Combining CROP and ATRP to synthesize pH-responsive poly(2-ethyl-2-oxazoline-b-4-vinylpyridine) block copolymers

Author(s)

Lima de Menezes, Rafael Natal ^[1] ; Felisberti, Maria Isabel ^[1]

Affiliation

^[1] Univ Estadual Campinas, Inst Chem, R Josue de Castro, POB 6154, BR-13084971 Campinas, SP - Brazil

• Document type: Journal article
• Source: Polymer Chemistry; v. 12, n. 32 JUL 2021.
• Web of Science Citations: 0

Abstract

Herein, we present the synthesis and characterization of block copolymers based on poly(2-ethyl-2-oxazoline), a biocompatible and stealth polymer that has drawn considerable attention in biomedical-related applications, and poly(4-vinylpyridine), a polydentate ligand and pH-responsive polymer, with interesting characteristics for application as optical, magnetic, electronic, catalytic and conductive materials, as well as in the biomedical field. Poly(2-ethyl-2-oxazoline-b-4-vinylpyridine) block copolymers were synthesized by the cationic ring-opening polymerization (CROP) of 2-ethyl-2-oxazoline (EtOx) followed by atom transfer radical polymerization (ATRP) of 4-vinylpyridine (4VP). P(EtOx-b-4VP) polymers with 4VP molar fractions ranging from 0.40 to 0.71 were obtained. These polymers presented a narrow molar mass dispersity (approximate to 1.2) and molar mass in the range of 6.4-10.5 kDa. The thermal properties of P(EtOx-b-4VP) were evaluated by differential scanning calorimetry (DSC) and their implication in the self-assembly in solution is discussed. The critical micellar concentration in water was determined by fluorescence spectroscopy and the self-assembly of P(EtOx-b-4VP) in water/DMF and basic aqueous solutions was studied by turbidimetry and dynamic light scattering (DLS). The morphology of the resulting structures was assessed by cryogenic transmission electron microscopy (cryo-TEM). Depending on the composition of polymer and solution, different structures, namely micelles, vesicles and worm-like micelles, can be formed. Concerning the interesting properties of PEtOx (stealth behavior and biocompatibility), as well as P4VP (pH-responsive polydentate ligand), these materials show potential for application in drug delivery, diagnostic imaging and as templates for inorganic materials. (AU)

• FAPESP's process: 15/25406-5 - Organizing matter: colloids formed by association of surfactants, polymers and nanoparticles
• Grantee: Watson Loh
• Support Opportunities: Research Projects - Thematic Grants
• FAPESP's process: 17/16615-5 - Synthesis and characterization of responsive polymer capsules
• Grantee: Rafael Natal Lima de Menezes
• Support Opportunities: Scholarships in Brazil - Doctorate (Direct)