Collapse of diblock copolymer in poor solvent. Molecular dynamics study

The modification of unsaturated polyesters (UPE) by poly (ethylene glycol) (PEG) end groups [1] and the computer simulation of the collapse of a singl e molecule of a diblock copolymer AB consisting of PEG (A) and UPE (B) bloc ks [2] were reported recently by us. In the present paper the static and dy namic characteristics of the final collapsed structure were investigated by a molecular dynamics simulation; The structure and the local dynamic of co llapsed homopolymers (AA and BE) were studied also. The initial conformatio ns in all cases were taken near completely extended ones. The final structu res of the diblocks are similar to the structure of a core (UPE) and shell (PEG) model. The differences in torsion angle distributions between diblock and homopolymer are maximal for the CCOC dihedral angles (both in UPE and PEG blocks). The orientational order of the COC vectors ('chords' along bac kbone of polymer chain) inside both blocks is larger in the diblock than in the homopolymer. Local orientational mobility of the COC vector and the tr anslational mobility of the monomers is larger in the diblock than in the h omopolymers for both blocks.