Hierarchical Structures in Lamellar Hydrogen Bonded LC Side Chain Diblock Copolymers

Abstract

We show that in a hydrogen bonded LC side chain diblock copolymer with lamellar morphology on the block copolymer level, two distinct packing mechanisms of the side chain blocks are possible depending on the amount of hydrogen bonded side chains. We mixed a hydrogen bonding mesogen, cholesteryl hemisuccinate (CholHS), with poly(1,2-butadiene)-block-poly(2-vinylpyridine) (PBd-P2VP) and poly(styrene)-block-poly(4-vinylpyridine) (PS-P4VP), in which the poly(vinylpyridine) act as host blocks, and we varied the CholHS to pyridine repeat unit ratio (x). With all x, a lamellar morphology on the block copolymer level was achieved. However, at low binding of CholHS to the host block, the CholHS side chains microphase separated into a single layer inside the poly(pyridine) lamellae resulting in a novel microphase separated structure. This includes, for example, the PS-P4VP sample with x = 0.25 and all the PBd-P2VP based samples since hydrogen bonding of CholHS to P2VP was sterically limited as revealed by infrared spectroscopy. No such limits were present in the rest of the PS-P4VP samples which showed a gradual shift from the single CholHS lamella morphology to exclusively liquid crystalline smectic layers oriented perpendicular to the block domain interfaces.

Controlling the shape of Janus nanostructures through supramolecular modification of ABC terpolymer bulk morphologies

“…Additionally, another factors come into play. Complexation of small molecules is also known to alter chain packing and induce chain stretching with increasing grafting density [23,51]. The effect of chain stretching is sketched in Figure 1e for the two extreme cases of 0% and 100% loading.…”

“…Much effort has been invested to identify the impact of smallmolecule complexation on the bulk behavior of diblock copolymers, where polystyrene-blockpoly(4-vinylpyridine) (PS-b-P4VP) has been the most prominent example. Supramolecular binding motifs comprise phenols (pentadecyl phenol, hydroxy-styrene, azobenzenes) [14][15][16][17][18][19][20][21], carboxyls (cholesteryl-hemisuccinate and pyrene butyric acid) [22][23][24], alkylated sulfonic acids [25], and phenol/sulfonate mixtures [26,27]. The supramolecular additive is often introduced into the minority phase to change or fine-tune its geometry (e.g.…”

Laser ablation of block copolymers with hydrogen-bonded azobenzene derivatives

“…It is well known that small molecules with hydrogen bonding donors can be hydrogen-bonded to P4VP blocks of PS-b-P4VP [22][23][24][25][26][27]. Here, the phenolic group in AzoR is a hydrogen bonding donor (Fig.…”

The Origin of Hierarchical Structure Formation in Highly Grafted Symmetric Supramolecular Double‐Comb Diblock Copolymers

“…[14] Multiple systems have been investigated during the past decades, including ionic, [15,16] halogen-bonded, [17] and hydrogen-bonded copolymers. [18] Still poly(4-vinylpyridine)(n-alkylphenol) x -based supramolecules are among the most studied comb-shaped copolymers (x represents the surfactant-to-monomer ratio). [19] Besides reduction of poly(4-vinylpyridine) (P4VP)'s glass transition temperature upon addition of small amounts of 3-pentadecylphenol (3-PDP) (its T g is already decreased by 100 °C for x = 0.5), [20] simultaneous self-assembly of the diblock (i.e., P4VP(3-PDP)/ PS) and comb block (i.e., P4VP/3-PDP) led to hierarchical structure formation in polystyrene-containing poly(4-vinylpyridine)(3-pentadecylphenol) x -b-polystyrene (P4VP(3-PDP) x -b-PS) comb-coil diblock copolymers.…”