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A tadpole shaped poly(-caprolactone) (PCL; Mn24 500) was made amphiphilic by grafting the two PCL tails with PEO. In the first step, a macrocyclic PCL was synthesized by ring-opening polymerization of -caprolactone (CL) initiated by a cyclic tin(IV) dialkoxide and stabilized by local intramolecular photo-cross-linking. In the second step, the polymerization of a mixture of CL and -chloro--caprolactone (ClCL) was resumed with formation of two activated chloride containing PCL tails. In the third step, the chlorides were converted into azides onto which alkynyl end-capped PEO was grafted by the copper-mediated Huisgen's cycloaddition 3 2, thus giving a “click” reaction. The thermal properties of the final copolymer and the precursors were analyzed by differential scanning calorimetry. The amphiphilicity of the final copolymer was confirmed by micellization in water. [ABSTRACT FROM AUTHOR]

A straightforward strategy is proposed for the derivatization of poly(-caprolactone) (PCL). First, statistical copolymerization of -chloro--caprolactone (ClCL) with -caprolactone (CL) was initiated by 2,2-dibutyl-2-stanna-1,3-dioxepane (DSDOP). In a second step, pendent chlorides were converted into azides by reaction with sodium azide. Finally, duly substituted terminal alkynes were reacted with pendent azides by copper-catalyzed Huisgen's 1,3-dipolar cycloaddition, thus a “click” reaction. According to this strategy, pendent hydroxyl and acrylate groups and atom transfer radical polymerization (ATRP) initiators were successfully attached to PCL. Similarly, amphiphilic graft copolymers were prepared by cycloaddition of an alkyne end-capped poly(ethylene oxide) (PEO) onto the azide substituents of the copolyester. The dependence of the grafting yield on the experimental conditions of the “click” reaction, i.e., temperature, solvent, and catalyst, was investigated. This strategy is very versatile because a large variety of aliphatic polyesters can be easily synthesized from a single precursor, easily prepared from commercially available compounds, merely by changing the alkyne involved in the Huisgen's 1,3-dipolar cycloaddition. Last but not least, PCL subsituted by azide groups does not have to be isolated after substitution of chlorides by sodium azide, and the “click” reaction can be carried out in a “one-pot” process. [ABSTRACT FROM AUTHOR]

The modification of aliphatic polyesters by the copper(i) catalyzed azide-alkyne cycloaddition (CuAAC) was successfully implemented in supercritical carbon dioxide (scCO2). Due to the remarkable properties of scCO2, the CuAAC reaction turned out to be quantitative even though the aliphatic polyesters used in this work were insoluble in scCO2Interestingly enough, the conditions were mild enough to prevent polymer degradation from occurring and finally, efficient removal of the catalyst (>96%) was achieved by scCO2extraction. [ABSTRACT FROM AUTHOR]