A Facile Strategy for Preparation of α-Heterobifunctional Polystyrenes with Well-Defined Molecular Weight.

A facile strategy for synthesis of α-heterobifunctional polystyrenes is reported. The novel functional polystyrenes have been successfully synthesized via a combination of atom transfer radical polymerization (ATRP) and chemical modification of end-functional groups. First, ε-caprolactone end-capped polystyrenes with controlled molecular weight and low polydispersity were prepared by ATRP of styrene using α-bromo-ε-caprolactone (αBrCL) as an initiator. Then, removal of the terminal bromine atom was performed with iso-propylbenzene in the presence of CuBr/PMDETA. Finally, ring-opening modifications of the caprolactone group were carried out with amines, n-butanol and H(2) O to produce novel polystyrenes containing two different functional groups at one end.

Synthesis, characterization and self-assembly of novel amphiphilic block copolymers with a polyhedral oligomeric silsesquioxanes moiety attached at the junction of the two blocks.

A novel well-defined amphiphilic block copolymer, with the polyhedral oligomeric silsesquioxane (POSS) moiety at the junction of the two blocks of polystyrene and poly(ethylene oxide) (PEO), was designed and synthesized. First, a macroinitiator containing a POSS moiety and a PEO chain was prepared and then atom transfer radical polymerization of styrene was carried out in the presence of the macroinitiator in bulk. The polymerization results show that the process bears the characteristics of controlled/living free radical polymerizations. The structure and molecular weight of the polymers were characterized by GPC, (1) H NMR, and FT-IR spectroscopy. The self-assembly behaviors of the polymers was investigated by TEM and SEM. It was observed that the polymers can self-assemble into vesicles in aqueous solution.

Synthesis of amphiphilic supramolecular miktoarm star copolymers by molecular recognition.

Synthesis of novel amphiphilic supramolecular miktoarm star copolymers has been achieved through complementary molecular recognition and interactions between carboxy groups and amino groups. Polystyrenes carrying two and one carboxy groups at the middle of the polymer chain are used as precursors to react with poly(ethylene oxide) (PEO) end-capped with a primary amine functionality (-NH(2) ) or a quaternary ammonium hydroxide functionality (-N(+) (CH(2) CH(3) )(3) OH(-) ). The result suggests that the basicity of the amine plays a key role in the molecular recognition procedure. The efficiency of ionic bond formation can be enhanced from 40% up to 97% by using PEO-N(+) (CH(2) CH(3) )(3) OH(-) instead of PEO-NH(2) . The obtained supramolecular polymers can be dissociated in dilute acid solution at room temperature.