Reorientation of Crystalline Block Copolymer Membranes by Phospholipid Hybridization

Abstract

Block copolymer (BCP) self-assembly and crystallization determine their fundamental mechanical, optical, and transport properties. Multiple physical and chemical routes to control BCP self-assembly have been developed over the years. In contrast, modulating the crystallization behavior, particularly crystallite size and orientation, has received considerably less attention. This paper underpins that 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) phospholipid additives enable precise control of BCP crystallization via a combination of interfacial and confinement effects. The assembly and crystallization behavior of methoxy-poly­(ethylene glycol)-b-poly­(ε-caprolactone) (mPEG-b-PCL) hybridized with DPPC was elucidated in solid-supported dry-film forms. mPEG-b-PCL/DPPC hybrid films coassemble into multilamellar structures with BCP and lipid domains stacked in registry across the film thickness. With small amounts of DPPC (3 wt %), mPEG-b-PCL/DPPC hybrid films unexpectedly exhibit nonadditive thermal conductivity, reaching ∼0.1 W m–1 K–1, a value considerably lower than pure BCP or DPPC films. Hybridization alters DPPC chain packing and induces specific PCL crystallite orientation at the nanoscale. PCL chains on the folding plane of an orthorhombic lattice optimize molecular interactions with vertically aligned DPPC alkyl chains by orienting PCL crystallites at a 20° tilt. These results enable new applications of polymeric systems in which switchable crystallization routes are used to tune heat transport.

Cooperative Self-Assembly of Lipid–Polymer Hybrids Stabilizing Highly Ordered Bicontinuous Cubic Phases in Air

“…One lamellar phase is lipid (MO/DOTAP)-rich, while another is a polymer (PBD- b -PEO)-rich phase (Figure D). The double lamellar systems are consistent with previous observations in DPPC/PBD- b -PEO binary mixtures where DPPC-rich and PBD- b -PEO-rich domains align in registry across multilayers. ,,, …”

“…Co-self-assembly of amphiphilic lipids and block copolymers (BCP) has fascinated a number of soft matter scientists over the past decade as a means to combine the advantages of both molecular systems in a single hybrid structure. − Phospholipids are abundant membrane lipids in nature, providing excellent biocompatibility and ability to aggregate into various structures in aqueous environments. Compared with lipids, BCPs have chemical versatility to modulate functional groups but come with a drawback of lower biocompatibility and being less dynamic when transforming from one phase to another.…”

“…Nonetheless, lipid–BCP mixtures hold a huge potential in creating nonlamellar structures with increasingly complex structures and topologies given that each amphiphile has the ability to self-assemble into various nanostructures. Indeed, recent studies on lipid–BCP hybrid membranes revealed more complex structures, e.g., patched surfaces ,, and compartmentalized domains stacked in registry across multilayers. ,, …”

“…Lipid–BCP hybrid membranes have synergistic structural and functional properties otherwise not achievable with the assembly of single components. Previous studies reported advanced properties of the lipid–polymer co-assemblies, e.g., improved mechanical stability, − controllable solubility of encapsulated solutes in membranes, − synergistic permeability of cargo drugs, − and control of polymer crystallization and thermal properties. , Research on lipid–BCP hybrid membranes has been mainly conducted on lamellar systems in the form of vesicles dispersed in water, , monolayer suspended in water, or bilayers on solid supports, − leaving a gap in our understanding of polymorphism of the lipid–BCP hybrid system. Nonetheless, lipid–BCP mixtures hold a huge potential in creating nonlamellar structures with increasingly complex structures and topologies given that each amphiphile has the ability to self-assemble into various nanostructures.…”

Bilayer-domain formation of thermoresponsive amphiphilic block copolymers in hybrid liposomes for synthetic molecular channels

“…[1][2][3] The combination of properties from the polymers and phospholipids allows for a wide range of functionalities, such as biocompatibility, increased stability in aqueous solutions, [4][5][6] controlled release by external stimuli, 7,8 and targeted delivery to specific organs or tissues. 9,10 As a result, hybrid vesicles have been the subject of extensive research to understand their fundamental physical properties [11][12][13][14][15][16][17][18] and to demonstrate their potential as carriers in drug-delivery systems and compartments for nanoreactors and artificial cells. [19][20][21][22][23] In addition to the functionalities mentioned above, the incorporation of specific polymers into liposomes can endow the vesicles with bespoke permeability.…”