Amphiphilic Block Copolymers Containing Regioregular Poly(3-hexylthiophene) and Poly(2-ethyl-2-oxazoline)

• Published in: Macromolecular chemistry and physics 2010-06, Vol.211 (12), p.1291-1297
• Main Authors: Alemseghed, Mussie G., Servello, John, Hundt, Nadia, Sista, Prakash, Biewer, Michael C., Stefan, Mihaela C.
• Format: Article
• Language: English
• Subjects: amphiphilic; Applied sciences; Block copolymers; cationic polymerization; cationic ring-opening polymerization; Coiling; Copolymers; Density; diblock copolymers; Exact sciences and technology; Nanocomposites; Nanomaterials; Nanostructure; Organic polymers; Physicochemistry of polymers; poly(2-ethyl-2-oxazoline); Polymers with particular properties; Preparation, kinetics, thermodynamics, mechanism and catalysts; regioregular poly(3-hexylthiophene); Segments; semiconducting polymers
• ISSN: 1022-1352; 1521-3935
• DOI: 10.1002/macp.200900725

Poly(3‐hexylthiophene)‐block‐poly(2‐ethyl‐2‐oxazoline) amphiphilic rod–coil diblock copolymers have been synthesized by a combination of Grignard metathesis (GRIM) and ring‐opening cationic polymerization. Diblock copolymers containing 5, 15, and 30 mol‐% poly(2‐ethyl‐2‐oxazoline) have been synthesized and characterized. The synthesized rod–coil block copolymers display nanofibrillar morphology where the density of the nanofibrills is dependent on the concentration of the poly(2‐ethyl‐2‐oxazoline) coil segment. The conductivity of the diblock copolymers was lowered from 200 to 35 S · cm−1 with an increase in the content of the insulating poly(2‐ethyl‐2‐oxazoline) block. By contrast, the field‐effect mobility decreased by 2–3 orders of magnitude upon the incorporation of the poly(2‐ethyl‐2‐oxazoline) insulating segment. Hydrophobic semiconducting poly(3‐hexylthiophene) has been incorporated in block copolymers with hydrophilic poly(2‐ethyl‐2‐oxazoline). The synthesized block‐copolymers have good conductivities. By contrast, the incorporation of hydrophilic insulating poly(2‐ethyl‐2‐oxazoline) resulted in the decrease of field‐effect mobilities by 2–3 orders of magnitude. Solvatochromic behavior of the poly(3‐hexylthiophene)‐block‐poly(2‐ethyl‐2‐oxazoline) diblock copolymers have been observed in tetrahydrofuran/water mixtures.