Three models for chain conformation of block copolymers in solution and in solid state

✍ Scribed by Anastasios Dondos; Dimitrios Papanagopoulos

• Publisher: John Wiley and Sons
• Year: 1996
• Tongue: English
• Weight: 1023 KB
• Volume: 34
• Category: Article
• ISSN: 0887-6266
• DOI: 10.1002/(sici)1099-0488(199605)34:7<1281::aid-polb10>3.0.co;2-6

✦ Synopsis

Solution properties of polystyrene-poly(methy1 methacrylate) (PS-PMMA) diblock copolymer, polystyrene-poly(tertiobuty1 methacrylate) (PS-PtBuMA) diblock copolymer, and poly(ethy1ene oxide)-polystyrene-poly(ethy1ene oxide) (PEO-PS-PEO) triblock copolymer have been measured by viscometry. The PEO-PS-PEO copolymer has been studied also in solid state by differential scanning calorimetry and by optical microscopy. All the block copolymers present a conformational transition in solution at a given temperature region which is relatively narrow. If below this transition temperature a copolymer adopts a segregated conformation (dumb-bell model), above this transition adopts a nonsegregated or pseudo-gaussian conformation, and vice versa. In the transition temperature region the copolymer adopts a compressed segregated conformation (core and shell model). If the passage from the solution to the solid state is performed in a given constant temperature in which the copolymer presents a segregated or nonsegregated conformation the same conformation is observed in the solid state (memory effect). 0