Dendrimer like star polymer based on beta-cyclodextrin with ABC type miktoarms

The present article reports the synthesis and self aggregation study of a novel dendrimer like star polymer based on beta-cyclodextrin (beta-CD), in which the primary alcoholic arms of beta-CD have been linked to ABC type miktoarm star polymers. Initially, 6-heptaazido-6-deoxy-beta-cyclodextrin (7N(3)-beta-CD) has been clicked with alkyne terminated poly(methyl methacrylate) (alkynyl-PMMA-Br), which has been synthesized through atom transfer radical polymerization technique. Subsequently, azidation has been done in order to prepare beta-CD(PMMA-N-3)(7). Parallelly, an amphiphilic block copolymer (alkynyl-PDLL-b-PNIPAAm), having an alkyne end group, has been synthesized by employing a mikto functional initiator having alcohol, xanthate and alkyne functionalities, in ring opening polymerization (ROP) of D,L-lactide (DLL) from -OH end, and reversible addition-fragmentation chain-transfer (RAFT) polymerization of N-isopropylacrylamide (NIPAAm) from xanthate end. Then, the desired star polymer has been synthesized by the click reaction between beta-CD(PMMA-N-3)(7) and alkynyl-PDLL-b-PNIPAAm. The polymers have been characterized by H-1 NMR, and gel permeation chromatography. Self aggregation of the star polymers has been investigated by H-1 NMR and fluorescence spectroscopy. Size of the micelles formed has been analyzed by dynamic light scattering and transmission electron microscopic techniques.