Effect of Systematic Hydrogenation on the Phase Behavior and Nanostructural Dimensions of Block Copolymers

Abstract

Unsaturated polydienes are frequently hydrogenated to yield polyolefins that are more chemically stable. Here, the effects of partial hydrogenation on the phase behavior and nanostructure of polyisoprene-containing block copolymers are investigated. To ensure access to the order-disorder transition temperature (T) over a wide temperature range, we examine copolymers with at least one random block. Dynamic rheological and scattering measurements indicate that T increases linearly with increasing hydrogenation. Small-angle scattering reveals that the temperature-dependence of the Flory-Huggins parameter changes and the microdomain period increases, while the interfacial thickness decreases. The influence of hydrogenation becomes less pronounced in more constrained multiblock copolymers.

Molecular Engineering of Nanostructures in Disordered Block Polymers

“…This suggests that the relatively thick and diffuse interfaces (and any compositional gradients) of these low-χ diblocks resulted in a less drastic change in the viscoelastic properties at the T ODT and thus a broader transition from order to disorder. Similar observations have been reported for block random and tapered copolymers. − Regardless, the complementary results from DSC and DMA strongly suggest that the diblock polymers with XS ≥ 26 are comprised of well-structured microphase-segregated domains, as is expected for either a fluctuating disordered or an ordered morphology.…”

Molecular and Structure–Properties Comparison of an Anionically Synthesized Diblock Copolymer of the PS-b-PI Sequence and Its Hydrogenated or Sulfonated Derivatives

“…academic research, since the final materials present exquisite properties and are not able to be synthesized using conventional polymerization techniques [43][44][45][46].…”

“…Their use as membranes [ 41 , 42 ] has been expanded to polyelectrolyte brushes as antimicrobial surfaces [ 22 ], drug delivery and/or controlled-release systems [ 22 , 32 ]. Post-polymerization modifications have gained remarkable interest in industrial applications as well as in academic research, since the final materials present exquisite properties and are not able to be synthesized using conventional polymerization techniques [ 43 , 44 , 45 , 46 ].…”

Morphological Studies of Solution‐Crystallized Thermoplastic Elastomers with Polyethylene Endblocks and a Random‐Copolymer Midblock

“…Block‐selective hydrogenation greatly increases the interblock thermodynamic incompatibility and significantly elevates the order–disorder transition temperature. [ 19,20 ] One approach to circumvent processing limitations associated with this family of TPEs is to substitute crystallizable hard blocks for the vitrifiable blocks to improve drug delivery, [ 21 ] catalysis, [ 22 ] optoelectronics, [ 23 ] electroactive media, [ 24 ] and hybrid materials. [ 25 ] Some crystallizable TPEs possess precise triblock copolymer architectures and well‐defined morphologies due to their synthesis via living anionic polymerization, [ 26,27 ] while others are more accurately described as randomly coupled multiblock copolymers.…”