Synthesis of Poly(lactide)s with Modified Thermal and Mechanical Properties.

The use of poly(lactide)-based materials is, in part, limited by their physical and mechanical properties. This article reviews the methods that have been employed to enable enhancement of the materials properties through synthetic manipulation of the polymer structure including block copolymer synthesis and modification of the lactide monomer structure, focusing on the application of ring-opening polymerization. In turn the effect of these structural modifications on the properties of the resultant materials are reported.

Synthesis and organocatalytic ring-opening polymerization of cyclic esters derived from l-malic acid.

The synthesis of 3-(S)-[(benzyloxycarbonyl)methyl]-1,4-dioxane-2,5-dione (BMD) and 3,6-(S)-[di(benzyloxycarbonyl)methyl]-1,4-dioxane-2,5-dione (malide) from commercially available l-malic acid is reported. Ring-opening polymerization (ROP) studies of BMD are reported showing that the controlled ROP of this monomer is possible in the absence of transesterification side reactions, despite the presence of side-chain esters, using 1-(3,5-bis(trifluoromethyl)phenyl)-3-cyclohexylthiourea and (-)-sparteine to catalyze the polymerization. The ROP of malide with this system was ineffective.

Development of amino-oxazoline and amino-thiazoline organic catalysts for the ring-opening polymerisation of lactide.

The ring-opening polymerisation of lactide by a range of amino-oxazoline and amino-thiazoline catalysts is reported. The more electron-rich derivatives are demonstrated to be the most highly active and polymerisation is well controlled, as evidenced by the linear relationship between the molecular weight and both the monomer conversion and the monomer-to-initiator ratio. Mechanistic studies reveal significant interactions between the monomer, initiator and catalyst and that the polymerisation is first order with respect to each of these components.

Metal free thiol-maleimide 'Click' reaction as a mild functionalisation strategy for degradable polymers.

The stoichiometric reaction between thiols and maleimide-functional poly(ester)s is demonstrated to be a quantitative, tolerant, mild and efficient method for polymer modification.