SUPRAMOLECULAR PLAs BY THE COOPERATIVE INTERACTION OF THE END GROUPS AND STEREOCOMPLEXATION

摘要

Supramolecular chemistry provides an important and versatile route to polymer materials with complex architectures and unique properties. The idea of our studies is to establish the influence of both stereocomplexation of enantiomeric polylactide chains and interactions of their functional groups on properties of a material obtained in that way. It has recently been shown that for stereocomplexes of the PLA formed from the low molecular weight enantiomeric polymers, the nature of end-groups (hydrophilic, hydrophobic or ionic) can affect the morphology of precipitated sterocomplex. In some cases the precipitation of corresponding stereocomplexes from 1,4-dioxane solution led to the formation of perfectly uniform microspheres able to create colloidal crystals . One of method improving physic-chemical properties of PLA is also introducing to PLA chains end groups able to self-assembling as the result of strong interaction. The quadruple hydrogen bonding unit 2-ureido-4-[1H]-pyrimidinone (UPy) has been known as a pendant unit off a polymer backbone and was used to improve material properties (see Fig. 1). Controlled ring-opening polymerization of L-lactide and D-lactide in tetrahydrofuran using 2-ureido-4[1H]-pyrimidinone (UPy)-functionalized initiators has yielded UPy-poly(lactide) (UPy-PLA-OH) chains which are able to self-assembling. Telechelic UPy-PLA-UPy was obtained by coupling reaction with appropriate diisocyanates. Molecular weight of these polymers was determined by ~1H NMR and SEC. The end group analysis were made using ~1H NMR and MALDI-TOF. Furthermore, using DSC method thermal properties of obtained supramolecular polymers and their stereocomplex were examined. SEM and AFM was used to determined morphology of these materials. The present work was financed by the project of National Science Centre DEC-2013/09/B/ST5/03616.