Synthesis of degradable poly(ε-caprolactone)-based graft copolymers via a “grafting-from” approach

Abstract

The controlled ring-opening polymerisation (ROP) of α-bromo-ε-caprolactone (αBrCL), a derivative of ε-caprolactone (εCL), and its copolymerisation with εCL is reported.

Thermally-induced hyperbranching of bromine-containing polyesters by insertion of in situ generated chain-end carbenes

“…[DPP] 0 = 1 : 2) was used in order to accelerate the reactions due to the lower propagation rate of BrCL. 30 After 4 h, the conversion of CL was near quantitative in all three polymerisations, whereas the conversion of BrCL was ca. 60% in all three experiments.…”

“…29 The BrCL monomer, 30,31 selected as the alkyl bromide, is a handle that enables copper-mediated radical polymerisations used in grafting techniques, [32][33][34][35] and is largely unreactive towards carbene insertion; 23,[26][27][28]45,50 the polycaprolactone (PCL)-based polymer serves as the hydrophobic and biodegradable segment in the material. 30,[36][37][38][39] Organocatalytic ROP 40 was selected for the initial polymerisation of the cyclic ester monomers. The ROP of CL and the subsequent copolymerisation of CL and BrCL was attempted using diphenyl phosphate (DPP) as the catalyst [41][42][43] and 4-[3-(trifluoromethyl)-3H-diazirin-3-yl] benzyl alcohol (TFDBA) as the initiator (Scheme S1, ESI † and Fig.…”

“…S33, ESI †). 30 The hyperbranching of the P(CL-co-BrCL) copolymers followed by 19 F NMR spectroscopy showing the unmasking of the carbene and its gradual insertion into the saturated polyester backbone until almost full completion (Fig. 2 and Fig.…”

“…S45, ESI †) can subsequently serve as suitable macroinitiators for the application of Cu(0)-mediated RDRP, [56][57][58][59][60][61] thus enabling 'graftingfrom' the PCL-based polymers. 30 Judicious choice of the synthetic method, grafting density, composition and length of the polymer backbone and side-arms, allows graft copolymers with unique structural characteristics and a range of functionalities to be prepared. [62][63][64][65] HBP2 was selected as the macroinitiator, and methyl acrylate (MA) was first polymerised in a graftingfrom approach, targeting 20 MA grafted units per initiating site (Br unit) for each arm.…”

Synthesis of Antibacterial Glycosylated Polycaprolactones Bearing Imidazoliums with Reduced Hemolytic Activity

“…alkylimidazolium (Im) onto PCL to mimic the cationic properties of antimicrobial peptides. The Poly(ε-caprolactone)-graft-butylimidazolium had only moderate MICs (32 μg/mL), reasonably good red blood cell selectivity (36) and relatively good fibroblast compatibility (81% cell viability at 100 μg/mL), indicating that combining the hydrophobic PCL backbone with the most hydrophilic butylimidazolium gives a good balance of MIC and cytotoxicity. On the other hand, the PCL-graft -hexylimidazolium and -octylimidazolium demonstrated better MICs (4-32 μg/mL), but considerably worse cytotoxicity.…”