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We report the successful synthesis of previously inaccessible poly(3-hydroxystyrene)-block-poly(dimethylsiloxane) (P3HS-b-PDMS) block copolymers (BCPs) with varying volume fractions, molecular weights, and narrow dispersities by sequential living anionic polymerization. The chemical structure and molecular weight were fully characterized by 1H NMR and gel permeation chromatography. The BCP phase behavior was investigated using small-angle X-ray scattering (SAXS) and transmission electron microscopy. Temperature-resolved SAXS measurements from symmetric disordered sample were used to determine the interaction parameter (ﾏ�) using mean-field theory. The results provide an estimate for interaction parameter, ﾏ⑨S/DMS(T) = 33.491/T + 0.3126, with an upper bound value of 0.39 at 150 ﾂｰC. The calculated ﾏ� for P3HS-b-PDMS is approximately 4 times higher than that observed in a commonly studied high-ﾏ� system, PS-b-PDMS. The ultrahigh interaction parameter observed here affords the formation of well-ordered materials at remarkably low molecular weight. The presence of both PDMS and P3HS provides significant versatility in terms of etch selectivity, while the hydroxystyrene domain offers additional functionality as it can be exploited for immobilizing functional organic moieties.

We explore the morphology and phase behavior of branched diblock macromonomers and their polymers. A series of macromonomers was synthesized based on a disubstituted norbornene. The first branch consists of polydimethylsiloxane (PDMS) while the second branch is a quasi-mesogenic structure incorporating one or more cyanobiphenyl (CB) moieties. Bottlebrush polymers with varying degrees of polymerization were prepared by “graft-through” ring-opening metathesis of the macromonomers. The molecules in the resulting library of macromonomers and bottlebrush polymers self-assemble to form classically observed microphase-separated structures, including spheres, hexagonally packed cylinders, bicontinuous gyroid, and lamellae. The systematic variation of molecular structure, molecular weight of each branch, and degree of polymerization of the polymers results in a diverse set of structures and properties. We report the observation of well-ordered lamellae and cylinders with d-spacings as low as 6.1 and 8.0 nm, respec...

A high level of the permanent asymmetry was built into the poly(N-methyl-N′-(2-isopropyl-6-methylphenyl)carbodiimide) system by introducing a bulky, substituted phenyl group which revealed a very interesting phenomenological behavior upon heating. This polymer undergoes P/M racemization upon thermal annealing, thus leading to the formation of a stereocomplexed structure. Predominantly P and M helices have been obtained through helix sense selective polymerization by using chiral BINOL-Ti(IV) diisopropoxide initiator with achiral N-methyl-N′-(2-isopropyl-6-methylphenyl)carbodiimide monomer. Upon thermal annealing, the specific optical rotation (SOR) of the single-handed polymer begins to decrease but never reaches zero. The SOR plateaus at a large value (−286° for M helices or +283° for P helices), and shortly thereafter the polymer forms a precipitate. The process that polymer undergoes is attributed to stereocomplexation between two complementary strands via racemization. Inspired by the phenomena analog...