Hydrogen-bonding amphiphilic low molecular weight plasticizing compounds to one block of diblock copolymers to form supramolecular comblike blocks leads to hierarchical self-assembly at the block copolymer (long) and amphiphile (short) length scales, in which lamellar-in-lamellar order and the related phase transitions have previously been shown to allow thermal switching of electrical and optical properties [Science 1998, 280, 557; Nat. Mater. 2004, 3, 872]. In this work other hierarchies and phase transitions are systematically searched, a particular interest being hierarchies containing gyroid structures and the related order−order transitions. Polymeric supramolecular comb−coil diblock copolymers consisting of a polystyrene (PS) coillike block and a supramolecular comblike block based on poly(4-vinylpyridine) (P4VP) are used, where the pyridines are either directly hydrogen bonded with 3-pentadecylphenol (PDP), i.e., PS-block-P4VP(PDP)1.0, or first protonated with methanesulfonic acid (MSA) and then hydrogen bonded to PDP, i.e., PS-block-P4VP(MSA)1.0(PDP)1.0. In this way the comblike block can be noncharged or charged. The morphologies were determined using transmission electron microscopy (TEM) and small-angle X-ray scattering (SAXS) at different temperatures. In the case of PS-block-P4VP(PDP)1.0, all classical diblock copolymer morphologies were observed at room temperature, where the P4VP(PDP)1.0 domains contain an additional lamellar structure due to the supramolecular comblike blocks. Here we report novel gyroid and hexagonal perforated layer morphologies, i.e., where the PS and P4VP(PDP)1.0 blocks form gyroid or hexagonal perforated layer order and the P4VP(PDP)1.0 domains have an internal lamellar order. Heating past ca. T = 60 °C causes an order−disorder transition within the P4VP(PDP)1.0 domains. Further heating leads to gradually reduced hydrogen bonding strength, and importantly PDP becomes soluble in PS at T > ca. 120 °C. At such temperatures PDP is found in both the P4VP and PS domains, thus leading to changes in the relative volume fractions of the domains, which in turn leads to order−order transitions. In PS-block-P4VP(MSA)1.0(PDP)1.0, typically lamellar and cylindrical block copolymeric structures were observed, where there was an additional internal lamellar order within the P4VP(MSA)1.0(PDP)1.0 domains. Coincidentally, an order−disorder transition within the P4VP(MSA)1.0(PDP)1.0 domains takes place at T = ca. 125 °C. Above that temperature, PDP is in both PS and P4VP(MSA)1.0 domains, but most interestingly at ca. T > 175 °C PDP becomes a nonsolvent for P4VP(MSA)1.0 and it is therefore expelled to predominantly to the PS domains. This manifests as an order−order transition. All samples exhibit at least two thermoreversible order−order transitions, and some of them show even five consecutive self-assembled phases as a function of temperature. Besides being amphiphilic, PDP can also be regarded as a plasticizer, i.e., relatively nonvolatile solvent, for the P4VP, PS, and P4VP(MSA)1.0 with cha...

Towards internal structuring of electrospun fibers by hierarchical self-assembly of polymeric comb-shaped supramolecules Ruotsalainen, T; Turku, J; Heikkila, P; Ruokolainen, J; Nykanen, A; Laitinen, T; Torkkeli, M; Serimaa, R; ten Brinke, G; Harlin, A Link to publication in University of Groningen/UMCG research database Citation for published version (APA): Ruotsalainen, T., Turku, J., Heikkila, P., Ruokolainen, J., Nykanen, A., Laitinen, T., ... Nykänen, A. (2005). Towards internal structuring of electrospun fibers by hierarchical self-assembly of polymeric comb-shaped supramolecules. Advanced materials, 17(8), 1048-+. https://doi

We show a concept where coordination of amphiphiles to one block of a block copolymer leads to polymeric supramolecules and self-organization and that mesoporous materials can be achieved with a dense set of polymer brushes at the surfaces upon cleaving the amphiphiles by extraction with a selective solvent. Polystyrene-block-poly(4-vinylpyridine) (PS-block-P4VP) is used with zinc dodecylbenzenesulfonate (Zn(DBS) 2) which can coordinate to the lone electron pairs of the pyridine nitrogens in the P4VP block, leading to complexes PS-block-P4VP[Zn(DBS)2]y. Coordination of Zn(DBS)2 and structure formation were investigated using Fourier transformation infrared spectroscopy (FTIR), small-and wideangle X-ray scattering (SAXS and WAXS), and transmission electron microscopy (TEM). Lamellar structure was observed and even points toward a structural hierarchy for high molecular weight block copolymers. FTIR, SAXS, and TEM showed that most of Zn(DBS) 2 can be extracted from such templates using methanol, leading to lamellar porous structures. P4VP brushes cover the resulting pore surfaces. The structures do not collapse probably due to the glassy PS and defects in the nonaligned structure. Compared to hydrogen bonding, coordination allows bonding of higher molecular weight amphiphiles due to the stronger attraction.