Synthesis and characterization of poly(linoleic-g-e-caprolactone) graft copolymers via ‘‘click’’ reaction and ring-opening polymerization
Linoleic acid modified with auto-oxidation, hydroxylation, bromination and azidation was usedto synthesis graft copolymers using Ѡ-alkyne-terminated poly(Ɛ-caprolactone) (alk-PCLs) via ‘‘click’’ reaction.In the first step, the polymeric linoleic acid (PLina) as macroinitiator was obtained by the autoxidation oflinoleic acid. Hydroxylation of the PLina was then carried out using diethanolamine to produce hydroxylatedpolymeric linoleic acid (PLina-OH). The PLina-OH was chemically modified with 2-bromopropionyl bromideto obtain bromo-functionalized polymeric linoleic acid (PLina-Br). This macroinitiator was thenmodified with sodium azide, resulting in azide polymeric linoleic acid (PLina-N3). In a parallel process, Ѡ alkyne-terminated poly(Ɛ-caprolactone) (alk-PCLs) were prepared via ROP of the Ɛ-caprolactone monomer inthe presence of propiolic acid, 3-butyn-1-ol, 5-hexynoic acid, and propargyl alcohol as the precursors andtin(II) 2-ethyl hexanoate (Sn(Oct)22) as the catalyst. These preliminary steps involved the synthesis of azideand alkyne compounds capable of being linked together via the alkyne-azide cycloaddition reaction catalyzedby copper (Cu(I)), which led to poly(linoleic acid)-g-poly(Ɛ-caprolactone) (PLina-g-PCL). The obtainedpolymers were characterized by proton nuclear magnetic resonance (1H NMR), Fourier-transform infrared(FTIR), differential scanning calorimetry (DSC), thermal gravimetric analysis (TGA) and elemental analysis.
Volume 133, 2021
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