Elucidation of Novel Nanostructures by Time-Lapse Monitoring of Polystyrene-block-Polyvinylpyridine under Chemical Treatment

摘要

Nanoscale micellar structures of polystyreneblock-npolyvinylpyridine (PS-b-PVP) diblock copolymers havenproven their effectiveness in lithography and biologicalndetection by serving as a choice material to produce nanoscalenguides and delivery systems in a straightforward and rapidnmanner through self-assembly. Such applications can greatlynbenefit from having high versatility for the selection ofntemplate sizes (pattern repeat spacing) and shapes (patternngeometry), especially when reaching a size regime thatnconventional top-down fabrication techniques may not readilynbe able to provide desired feature dimensions. Selective chemical treatments of the diblock copolymers are one of the usefulnmethods yielding a rich set of nanoscale features on PS-b-PVP. Exposure to selective vapor can induce reorganization of thenpolymeric chains of PS-b-PVP and alter the original micellar nanostructures. In this Article, we identify for the first time a host ofnnew nanostructures formed at different stages of chloroform vapor annealing by performing time-lapse atomic force microscopynmeasurements. We determine key, time-dependent, topological parameters defining each nanostructure and present the likelynscenario of polymeric chain reorganization during the morphological evolution of the diblock polymer nanodomains over time.nWe also ascertain intermediate morphological states containing the characteristic nanostructures from two consecutive phases asnwell as transition states appearing for a short time in between two subsequent phases. These research efforts may not onlynprovide insight into the domain evolution steps of the micellar to the cylindrical structures of PS-b-PVP but may also bentechnologically advantageous for subwavelength mask design in nanolithography and high-density array fabrication in highnthroughput biodetection.