A simple strategy was explored to systematically control the phase transition of an amphiphilic bottlebrush block copolymer (AmBBCP), poly-[(norbornene-graf t-styrene)-block-(norbornene-graf t-hydroxystyrene)], with polymeric additives, such as poly(ethylene glycol) methyl ether (mPEG), poly(2-vinylpyridine) (P2VP), and poly(methyl methacrylate) (PMMA). The precursor polymers, poly[(norbornene-graf t-styrene)-block-(norbornene-graf t-4-tert-butoxystyrene)], were synthesized by sequential ring-opening metathesis polymerization of ω-endnorbornyl polystyrene and poly(4-tert-butoxystyrene). Acid hydrolysis of the tert-butyl groups in the precursor resulted in the AmBBCP with an ultrahigh molecular weight (∼2880 kDa) and relatively low dispersity (∼1.21). The disordered structures of neat AmBBCP were transformed to ordered lamellae by solvothermal annealing. AmBBCP and mPEG blended well because of H-bonding, maintaining well-ordered lamellae up to 40 wt % mPEG. The phase transition from ordered to disordered state occurred when increasing more than 50 wt %. The AmBBCP blended with P2VP and PMMA was compared. The effect of mPEG on phase transition, domain size, and refractive index and the photonic properties were determined.

Anionic polymerization is one of the most powerful techniques for preparation of well-defined polymers. However, this well-known and widely employed polymerization technique encounters major limitations for the polymerization of functional monomers containing heteroatoms. This work presents the anionic polymerization of 2-phenyl-5-(6-vinylpyridin-3-yl)-1,3,4-oxadiazole (VPyOzP), a heteroatom monomer that contains both oxadiazole and pyridine substituents within the same pendant group, using various initiating systems based on diphenyl­methyl potassium (DPM-K) and triphenyl­methyl potassium (TPM-K). Remarkably, well-defined poly­(2-phenyl-5-(6-vinylpyridin-3-yl)-1,3,4-oxadiazole) (PVPyOzP) polymers having predicted molecular weights (MW) ranging from 2200 to 21 100 g/mol and polydispersity indices (PDI) ranging from 1.11 to 1.15 were prepared with TPM-K, without any additional additives, at −78 °C. The effect of temperature on the polymerization of PVPyOzP was also studied at −78, −45, 0, and 25 °C, and it was observed that increasing the polymerization temperature produced materials with unpredictable MW’s and broader molecular weight distributions. Furthermore, the nucleophilicity of PVPyOzP was investigated through copolymerization with methyl methacrylate and acrylonitrile, where only living poly­(methyl methacrylate) (PMMA) prepared by DPM-K/VPPy and in the absence of additives such as lithium chloride (LiCl) and diethyl zinc (ZnEt2) could be used to produce the well-defined block copolymer of PMMA-b-PVPyOzP. It was also demonstrated by sequential monomer addition that the nucleophilicity of living PVPyOzP is located between that of living PMMA and polyacrylonitrile (PAN). The pyridine moiety of the pendant group also allowed for quaternization and produced PQVPyOzP homopolymer using methyl iodide (CH3I) and bis­(trifluoro­methyl­sulfonyl)­amide [Tf2N–]. The resulting charged polymer and counterion complexes were manipulated and investigated for potential use as membranes for carbon dioxide (CO2) capture.