Synthesis of novel poly(ethylene glycol) based amphiphilic polymers

The synthesis of new amphiphilic polyesters based on poly(ethylene glycol) (PEGs) and studies on their solution properties are reported. Two novel monomers, dimethyl 5-n-butoxy isophthalate (2) and dimethyl 5-n-octoxy isophthalate (3) were synthesized. Three series of novel amphiphilic polyesters, i.e. poly(ethyleneoxy isophthalate)s (10–15), poly(ethyleneoxy n-butoxy isophthalate)s (16–21) and poly(ethyleneoxy n-octoxy isophthalate)s (22–27) have been synthesized from PEGs of different sizes and dimethyl isophthalates 1–3 via the transesterification–polycondensation using dibutyltin diacetate as a catalyst. The structures of the polyesters were established from a detailed analysis of their spectra, i.e. FTIR, 1H-NMR (one- and two-dimensional) and 13C-NMR. By adjusting the ratio of hydrophobic (diesters) and hydrophilic (PEGs) segments in polymers, their main chain structures and solution properties could be changed. The viscosity molecular weights (Mv) of polymers, obtained from Mark–Houwink–Sakurada relationship having poly(ethylene terephthalate) as a model, were in the range of 4500–32,000 g/mol. Intrinsic viscosities were studied based on polymer backbone length (PEGs effect) and pendant group (diesters effect) and these were found to be dependent on molecular weights of the PEGs used.