Polymethylene-b-poly(acrylic acid) diblock copolymers: Morphology and crystallization evolution influenced by polyethyene polyamine with dual confinement effects

Abstract

In this work, we systematically investigated the aggregation and confined crystallization behavior of polymethylene-b-poly acrylic acid diblock copolymers (PM-b-PAA, M93A94) under the influence of polyethyene polyamine (PPA). With the increasing molar ratio of PPA, the morphologies of PM-b-PAA micelles experienced sphere-to-band-to-sheet transformations with regular changes of sizes on cooling from 80 °C mixed solution. Further investigation of the crystalline feature of PM-b-PAA indicated that the crystallization of PM block was profoundly restrained by PPA with the dual confinements, i.e., chemical and physical confinement which exerted through the hierarchical hydrogen bonding and 3D hydrogel network, respectively, in the mixed system. In particular, when the PPA and PM-b-PAA aqueous solution were mixed with equivalent volume, hydrogels was accessible. And rheology property indicated that the BCP/PPA-0.5 hydrogels hold the maximal storage modulus G′, and meanwhile the minimum loss tangent, tanδ.

Specific Disassembly of Lamellar Crystalline Micelles of Block Copolymer into Cylinders

“…Recently crystallization-driven self-assembly (CDSA) of block copolymers (BCPs) has gained great attention because of its unique characteristics and advantages. − First, the shape of crystalline micelles of BCPs can be regulated by changing crystallization conditions as well as chain structure. − Second, since polymer crystals can grow, crystalline micelles with a uniform size may be prepared under suitable crystallization conditions. − Moreover, complex and hierarchical structures in one, two, and three dimensions can be constructed via epitaxial crystallization. − …”

Recent progress in block copolymer crystallization

“…Depending on the thermodynamic stability of the micelles, crystallization is confined to the core, particularly for sphere and cylinder micelles . Likewise, breakout‐like crystallization is possible and disrupts the micelle core leading to further aggregation of individual micelles transitioning to a new micelle morphology, usually cylindrical or branched‐cylinders, or to lamellar, single‐crystal‐like platelets . Wang and coworkers designed PEO‐ b ‐PLLA copolymers with different M n PLLA to study the role of hydrophobic block length and solvent quality (PEO corona solvation) on solution self‐assembly.…”

“…Changes in morphology have been shown to be sensitive to additives as well . These additives manipulated either the corona block or the core block . He and coworkers prepared micelles of poly(acrylic acid)‐ b ‐polymethylene (PAA‐ b ‐PM) with crystalline PM cores using the thermal treatment method.…”

“…These additives manipulated either the corona block or the core block . He and coworkers prepared micelles of poly(acrylic acid)‐ b ‐polymethylene (PAA‐ b ‐PM) with crystalline PM cores using the thermal treatment method. When adding polyethylene polyamine (C 2n H 5n N n ), the fractionally deprotonated PAA block and protonated amines complexed to change the volume of the corona.…”

One‐dimensional growth kinetics for formation of cylindrical crystalline micelles of block copolymers

“…The crystallization‐driven self‐assembly (CDSA) of BCPs in solution leads to formation of crystalline micelles, in which the insoluble micellar core is crystalline. So far, CDSA has been reported for many core‐forming polymers, including poly(ferrocenyldimethylsilane) (PFS), polyethylene (PE), poly(ethylene oxide) (PEO), poly(ε‐caprolactone) (PCL), poly( l ‐lactide) (PLLA), poly(3‐hexyl thiophene) (P3HT), poly( p ‐dioxanone), polyselenophene, poly( p ‐phenylenevinylene), and polyfluorene . The introduction of crystallization driving force endows CDSA of BCPs some unique features. More abundant micellar morphologies can be achieved via changing the relative strength of crystallization and solvophilic/solvophobic force …”