| Abstract
| - The organometallic−inorganic diblock copolymer poly(ferrocenyldimethylsilane-b-dimethylsiloxane)(PFDMS-b-PDMS) with a 1:6 block ratio unexpectedly forms long rodlike micelles rather than sphericalstructures in a variety of PDMS-selective n-alkane solvents when the solutions are prepared at or near ambienttemperature. The cylindrical structures represent the thermodynamically preferred morphology and consist ofan iron-rich PFDMS core and a corona of PDMS. The length of the micelles can be varied from 70 nm to 10μm by altering the method of sample preparation. In addition, the dimensions of the micellar core can becontrolled through variations in the length of the PFDMS block, which is achieved by altering the molecularweight of the diblock copolymer while maintaining a constant block ratio. In contrast, when micelles areformed above the Tm of PFDMS (ca. 120−145 °C), spherical aggregates are formed, which suggests thatcrystallization of the core polymer is the driving force for the formation of wormlike micelles below Tm.Furthermore, the analogues with amorphous polyferrocene blocks, poly(ferrocenylmethylphenylsilane-b-dimethylsiloxane) (PFMPS-b-PDMS) and poly(ferrocenylmethylethylsilane-b-dimethylsiloxane) (PFMES-b-PDMS), form spherical micelles in hexane at room temperature. This lends further support to the propositionthat the crystalline nature of the PFDMS block plays a pivotal role in the unexpected formation of cylindricalmicelles. To provide an application of this concept, an analogous PFDMS block copolymer with polyisoprene,PI-b-PFDMS, was prepared and, as predicted, was found to form cylindrical micelles in hexane.
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