A series of peripherally clickable hyperbranched polyesters were prepared wherein the stiffness of the spacer segment between branching junctions was systematically varied. Three different four-carbon spacers were studied: one was fully saturated (HBPC4-S), another bears a double bond (HBPC4-DBc), and a third carries a triple bond (HBPC4-TB); in the case of the sample with a double bond c indicates cis-rich isomer. The glass transition temperatures of the HB polyesters were seen to increase with the stiffness of the spacer segment from 27 to 60 °C. Furthermore, when the peripheral propargyl groups of the HB polyesters were quantitatively clicked with a crystallizable docosyl (C-22) azide, all the derivatives exhibited sharp melting/crystallization peaks in the DSC traces, indicative of segregation and colocalization of the peripheral segments. WAXS data confirmed the crystallization of the alkyl segments in a paraffinic lattice, while SAXS profiles revealed the formation of a lamellar morphology; the interlamellar spacing reflected the compactness of the HB polymeric core and also the adaptability of the core toward the self-segregation. Whereas the effect of such structural variations in linear polyesters has been examined extensively, this represents the first study that reveals the implications chain stiffness and geometry on the properties of hyperbranched polymers.

Using an orthogonally clickable strategy, the accessibility of internal allyl groups in jacketed HBPs, bearing either PEG or docosyl peripheral segments, was shown to depend both on the size and relative polarity of the reactant thiol.

Crosslinked amphiphilic hydrogels, prepared using a peripherally clickable hyperbranched polyester (HBP) and PEG-diazides of different molecular weights, were used to ligate Cu utilizing the triazole rings formed by the alkyneazide click reaction. Since only a fraction of the peripheral propargyl groups in the HB polyester are needed to generate the crosslinked polymer, the remaining were clicked with different types of azides, such as MPEG azide, decyl azide or 4-methylbenzyl azide, to create a molecular jacket around the catalytic sites that can potentially influence the catalytic activity and reaction outcome. The crosslinked films ligated with Cu functioned very effectively to catalyse alkyne-azide click reactions, both in water and in organic solvents; the nature of the molecular jacket around the catalytic site had a clear influence the reaction rate, which depended upon the relative solubilities of the reactants. The gel-supported catalyst films were reused multiple times with little loss in catalytic activity.