A comparative study of Amphiphilic PAMAM dendrimers at the air-water interface with different hydrophobe attachment groups

Generation 0 through 5 polyamidoamine (PAMAM) dendrimers with three different types of groups connecting to hydrophobic C-12 tails and one type of group connecting to C-18 tails were synthesized and studied as monolayers at the air-water interface with a Langmuir trough. The molecular areas were significantly influenced by the size and the type of connecting group. Higher-generation (e.g., G4 and G5) amphiphilic PAMAMs with amide connecting groups were more responsive to changes in compression rate and subphase temperature and less stable than the corresponding opened epoxide- or ester-connected counterparts. Intramolecular (and possibly also intermolecular) attractive hydrogen-bond interactions between the amide connectors are proposed as the reason for this behavior.