Amphiphilic triblock terpolymers consisting of poly(n-hexyl isocyanate) and poly(ethylene glycol): Preparation and characterization

Amphiphilic triblock terpolymers, poly(n-hexyl isocyanate)-b-poly(ethylene glycol)-b-poly(n-hexyl isocyanate) (defined as PHIC-b-PEG-b-PHIC) was synthesized by using CpTiCl₂-PEG-CpTiCl₂ as macromolecular initiator. GPC, FT-IR, ¹H NMR and DSC analyses confirmed the formation of amphiphilic block terpolymers. UV-vis spectra demonstrated that the PHIC block in the triblock terpolymers adopted helical structures. Increasing temperature is not favorable to maintain the helical structures. In toluene, tetrahydrofuran and chloroform, the PHIC-b-PEG-b-PHIC triblock terpolymers formed liquid-crystalline. At a concentration of 217.4 and 375 mg/ml in toluene, the triblock terpolymer crystalline structures exhibited rod-like and spheric shapes, respectively. A further increase of the concentration of the triblock terpolymer to 703.13 mg/ml led to oriented liquid-crystalline structures. Contact angle measurements demonstrated that the hydrophilicity of the triblock terpolymers was improved with increasing the content of PEG.