Defining Morphological Transformations of "Soft Nature" Diblock Viscoelastic Structured Polymers

Structured diblock copolymer liquidsconsisting exclusivelyof"soft" segments with glass-transition temperatures wellbelow room temperature have not been studied extensively in the literaturein terms of self-assembly properties to date. Despite their "softnature", these types of diblock copolymers are capable of formingwell-ordered topologies at low temperatures. This ability is attributedto their low dispersity indices (D) and relativelyhigh Flory-Huggins interaction parameter, & chi;, betweenthe chemically different involved blocks. Herein, we report a comprehensivestudy of the synthesized copolymers on molecular and thermal characterization,along with the structure-property relationship of two typesof polydiene-b-polysiloxane copolymers by manipulatingthe monomer's ratio during synthesis. Emphasis was given tothe self-assembly behavior when the molecular characteristics (volumefraction and degree of polymerization) of the involved blocks variedto assess the limits of the phase stability. Specially, poly(butadiene)(PB1,2) or poly(isoprene) (PI1,4) was utilizedas the first segment, while poly(dimethylsiloxane) (PDMS) was usedas the second block in all cases. The molecular characteristics'diversity combined with the ability to design/synthesize block copolymerswith well-ordered phases ranging from spheres, cylinders, lamellar,and finally network structures is quite promising for nanotechnologyapplications in soft electronics. Also, the inherent properties ofthe copolymers, such as thermal stability, hydrophobicity, and flexibility,render them potential candidates for stretchable and/or wearable applications.