Recent progress in the synthesis of aliphatic polyesters, substituted by pendent functional groups, has been reviewed. Two main strategies have to be distinguished. The first route consists of the ring‐opening polymerization of ε‐caprolactone substituted by various functional groups, protected if needed, in α‐ or γ‐position. In a second strategy, the functional groups are grafted onto preformed polyesters chains in α‐position of the carbonyl groups. α‐chloro‐ε‐caprolactone is quite an interesting monomer because, after polymerization, the activated chloride can be easily derivatized by atom transfer radical addition and “click” chemistry, respectively. Similarly, γ‐acrylic‐ε‐caprolactone is precursor of (co)polyesters well‐suited to derivatization of the pendent double bonds by Michael addition.
The Michael-type addition of aliphatic (co)polyesters onto gamma-acryloyloxy epsilon-caprolactone units is a very straightforward technique of functionalization and grafting, which is tolerant to a variety of functional groups and does not require intermediate protection/deprotection steps.
Well‐defined copolymers of biocompatible poly(ϵ‐caprolactone) (PCL) and poly(ethylene oxide) (PEO) are synthesized by two methods. Graft copolymers with a gradient structure are prepared by ring‐opening copolymerization of ϵ‐caprolactone (ϵCL) with a PEO macromonomer of the ϵCL‐type. The ϵCL polymerization is initiated by a PEO macroinitiator to prepare diblock copolymers. These amphiphilic copolymers are used as stabilizers for biodegradable poly(D,L‐lactide) (PLA) nanoparticles prepared by a nanoprecipitation technique. The effect of the copolymer characteristic features (architecture, composition, and amount) on the nanoparticle formation and structure is investigated. The average size, size distribution, and stability of aqueous suspensions of the nanoparticles is measured by dynamic light scattering. For comparison, an amphiphilic random copolymer, poly(methyl methacrylate‐co‐methacrylic acid) (P(MMA‐co‐MA)), is synthesized. The stealthiness of the nanoparticles is analyzed in relation to the copolymer used as stabilizer. For this purpose, the activation of the complement system by nanoparticles is investigated in vitro using human serum. This activation is much less important whenever the nanoparticles are stabilized by a PEO‐containing copolymer rather than by the P(MMA‐co‐MA) amphiphile. The graft copolymers with a gradient structure and the diblock copolymers with similar macromolecular characteristics (molecular weight and hydrophilicity) are compared on the basis of their capacity to coat PLA nanoparticles and to make them stealthy.
This work deals with the self-assembly in water of ABC miktoarm star terpolymers consisting of hydrophobic poly(-caprolactone), hydrophilic poly(ethylene oxide) (PEO), and pH-sensitive poly(2-vinylpyridine) (P2VP). A variety of experimental techniques were used, including dynamic light scattering, transmission electron microscopy, and zeta potential. Special attention was paid to the pH dependency of the supramolecular self-assemblies. A key observation is the capability of the miktoarm terpolymers to form micelles stable over the whole range of pH, although a transition was observed from neutral to highly positively charged nanoobjects upon decreasing pH.
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