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A series of salicylic acid-derived poly(anhydride-esters) were synthesized by melt polym erization methods, in which the structures of the molecule ("linker") linking together the two salicylic acids were varied. To determine the relationship between the linker and the physical properties of the corresponding poly(anhydride-ester), several linkers were evaluated including linear aliphatic, aromatic, and aliphatic branched structures. For the linear aliphatic linkers, higher molecular weights were obtained with longer linear alkyl chains. The most sterically hindered linkers yielded lower molecular weight polymers. The thermal decomposition temperature increased with the alkyl chain length, but the glass transition temperature decreased, due to the enhanced flexibility of the polymer. The highest glass transition temperatures were obtained by using aromatic linkers as a result of increased π-π interactions. Water contact angles determined the relative hydrophobicity of the polymers, which correlated to hydrolytic degradation rates; i.e., the highest contact angle values yielded the slowest degrading polymers.

A series of novel amphiphilic scorpion-like macromolecules (AScMs) were designed for optimized drug encapsulation and transport. The branched hydrophobic domains were prepared by acylation of mucic acid with varying chain lengths of acyl chlorides. Monohydroxylated poly(ethylene glycol) (PEG) was conjugated onto the hydrophobic domain to form the final polymers. Fluorescence spectroscopy and dynamic light scattering were performed to determine the critical micelle concentrations (cmc) and aggregation particle sizes, respectively. By changing the length of PEG and acyl chains, the physicochemical properties (e.g., Mw, HLB, Tm, cmc) of AScMs are controlled. Low cmc values (10 -5 -10 -7 mol/L) and small particle sizes (10-20 nm) of AScMs are potentially applicable for lipophilic drug delivery applications.

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