Hierarchical Microstructures Self‐Assembled from Linear Multiblock Copolymers in Thin Films

copolymers and pentadecylphenol (PDP) which can be attached to the P4VP blocks via a hydrogen bond. [3,4] In the subsequent work, by using the concepts of supramolecular self-assembly, they observed the formation of lamellar-within-lamellar, lamellar-within-cylindrical, cylindricalwithin-lamellar, spherical-within-lamellar and lamellar-within-spherical morphologies at different volume fraction. [6] In additional to the non-covalent bond in the supramolecules, such as hydrogenbond, [7] ionic interactions, [8] covalent bond was used to synthesize the undecablock copolymer (PISISISISIP), which consists two long poly(2-vinylpyridine) (P) blocks on each end and five short polyisoprene (I) plus four short polystyrene (S) blocks in the middle. [9] They reported the observation of five layers lamellae-in-lamellae hierarchical structure, which results from the large number of molecular configurations in this hierarchical structure. [9] Later, they observed many hierarchical structures and confirmed the phase transition from spheres-in-lamellae into cylinders-in-lamellae, lamellae-in-lamellae, and coaxial cylindrical structures, and finally into onion-like spherical structure as the volume fraction of the tail block increases. [10] However, the number of configurations is only one part of entropy. In addition to the configuration entropy, conformation entropy and enthalpy effect are crucial to the phase behavior. By capturing these effects, researchers study the formation mechanism of hierarchical lamellae by using Self-Consistent Field Theory (SCFT). [11][12][13][14][15][16][17] Besides SCFT, strong-segregation theory (SST) [18,19] and dissipative particle dynamics (DPD) [20,21] were extensively used to study the phase behavior of a number of linear multiblock copolymers. [18,20,22,23] Interestingly, by exhibiting the dynamics process of the formation of hierarchical structures, the small-length-scale nanostructures was found to form behind large-length-scale nanostructures, which shows great guidance for the controllable formation of the hierarchical morphologies. [17,21] Besides the parallel lamellae-in-lamellae structures, perpendicular hierarchical structure was reported by Bates using poly(CECEC-P) (C: cyclohexylethylene, E: ethylene, P: propylene) hexablock terpolymer by sequential anionic polymerization followed by catalytic hydrogenation. [24,25] By using the powerful frame of SCFT, the mechanism of this perpendicular structure was well understood, [12] and a number of hierarchical structures including perpendicular or parallel lamellae, cylinders, and Hierarchical StructuresDue to more than two length scales properties, hierarchical structures, which can combine several properties and respond to multi external conditions, have attracted the continuing attention over the past decades. The corresponding phase diagram of different hierarchical structures is crucially important for the observation of these morphologies. In this paper, the phase diagram of these hierarchical structures in A(BC) 2 B multiblock copolyme...

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Phase Diagram of Hierarchical Structures Formed from A(BC)₂B Multiblock Copolymers

Shao

Zhang

et al. 2019

“…The calculation process of MD is more complicated and takes longer time. Therefore, for large molecular weight systems such as polymers, the coarse‐grained model is advantageous for reducing calculation time, and thus it is widely used in complex systems like polymer self‐assembly . The coarse‐grained model of DPD is dividing several atoms or groups into one bead.…”

Section: Methodsmentioning

confidence: 99%

Relevance of the Polymeric Prodrug and Its Drug Loading Efficiency: Comparison between Computer Simulation and Experiment

Luο

Wang

et al. 2019

In order to explore the relationship between drug grafting ratio of polymeric prodrug and its drug loading efficiency, molecular dynamics simulation is utilized to calculate the compatibility of polymeric prodrug with 5‐aminolevulinic acid methyl ester (m‐ALA) and H2O first. Then, dissipative particle dynamics simulation is used to observe the morphologies of drug‐loaded micelles. Then, designed polymeric prodrugs are synthesized, drug‐loaded micelles and blank micelles are prepared by dialysis method, and the drug loading content (DLC) and encapsulation efficiency are measured. The computer simulation shows that polymer–drug compatibility gets better as the m‐ALA grafting ratio increases from 0% to 100%. Experimental results show that the DLC of micelle changes from 4.05% (0% grafting ratio) to 8.99% (100% grafting ratio). Through comparison, the experimental results are proven to be consistent with the computer simulation results, revealing that the drug loading efficiency of polymer micelles could be improved by grafting drugs.

“…Combining the effect of the enthalpy, Li and Shi studied the formation of LL structures and found that low IS interaction and high PI and PS interactions favor the formation of LL with more mid‐thin layers. [ 19 ] In addition to the LL nanostructure, cylinders‐in‐lamellae, lamellae‐in‐lamella , cylinders‐in‐ cylinder , and spheres‐in‐sphere, were also reported both in theory [ 20–30 ] and experiment. [ 31–34 ] Importantly, a series of multicontinuous network structures with controllable channels, including multicontinuous gyroid and O 70 network morphologies were obtained by using an effective design principle.…”

Section: Introductionmentioning

confidence: 99%

Emergence and Stability of Hierarchical Structures under Cylindrical Confinement

Chen

2023

Focusing on the formation of hierarchical structure under cylindrical confinement, the self‐assembly of A(BC)2B multiblock copolymer of chain length N in a nanopore with size R is studied using the self‐consistent field theory. The hierarchical concentric ring (HCk), hierarchical perforated cylinder (HPk), hierarchical helix (HHk), and even hierarchical disk (HDk) is obtained with different number of mid‐thin layers k via a proposed design principle. The results show that large pore size and χAB favor the hierarchical structure with more k, while χBC prefers hierarchical structure with less k, consistent with the results of hierarchical structure in bulk. By investigating the effect of the volume fraction of the tail A block (fA), the phase transition sequence, HCk → HPk → HHk → HDk is explored, which shares the same transition of multiblock copolymer in bulk with Lk → Gk → Ck → Sk. Finally, the phase diagram with respect to the fA and R is explored, where the stability regime of these hierarchical structures is well understood. The results provide a compelling panacea for the fabrication of hierarchical 3D nanostructures under confinement.