Subscriber access provided by HACETTEPE UNIVERSITESI KUTUPHANESI
Article
Soft Confinement-Induced Morphologies of the blends of AB diblock Copolymers and C homopolymers Jun Zhang, Weixin Kong, and Hai Ming Duan Langmuir, Just Accepted Manuscript • DOI: 10.1021/acs.langmuir.7b00181 • Publication Date (Web): 09 Mar 2017 Downloaded from http://pubs.acs.org on March 14, 2017
Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a free service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are accessible to all readers and citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.
Langmuir is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.
Page 1 of 37
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Langmuir
Soft Confinement-Induced Morphologies of the blends of AB diblock Copolymers and C homopolymers Jun Zhang, Weixin Kong*, Haiming Duan Physics Science and Technology College of Xinjiang University, Urumqi, Xinjiang, 830046, China
____________________________________________________ *
[email protected] 1
ACS Paragon Plus Environment
Langmuir
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Page 2 of 37
Abstract Self-assembly behavior of the blends of AB diblock copolymers and C homopolymers in soft confinement is studied by using a simulated annealing method. Polymer solution droplets in a poor solvent environment realize the soft confinement. Several sequences of soft confinement-induced copolymer aggregates with different shapes and internal structures are predicted as functions of the size of confinement, the number ratio of AB diblock copolymers to C homopolymers, the volume fraction of blocks, the selectivity of confinement’s surface, the incompatibility between blocks, and the competition between two block-homopolymer interactions. Simulation results demonstrate that those factors are able to tune the morphology of the aggregates precisely. We anticipate the rules achieved here is helpful to fabrication of polymeric particle with pre-designed morphology. Keywords: diblock copolymers, homopolymers, self-assembly, soft confinement, polymeric aggregate
2
ACS Paragon Plus Environment
Page 3 of 37
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Langmuir
Introduction The self-assembly of block copolymers in soft confinement has attracted much scientific interest due to the rich morphologies of polymeric nanoparticles and their potential applications in many fields [1]. The soft confinement is realized by several approaches in experiment at presents. One is based on fabrication and subsequently evaporation of solution droplet such as aerosol approach [2-6], micro-fluid flow [7-9], emulsion [10-19]; other is direct precipitation of block copolymer in solution [20-28]; the latest approaches are relatively complex. One is solvent annealing of entities generated from Rayleigh instability of polymer nanotubes inside AAO capillary channels [29-31]. The other is degradation of polymeric particle which is fabricated by emulsion and subsequently evaporation of initial solution [32]. Kim and Yi summarized the methods to fabricate block copolymer particles recently [33]. Those methods enable scientists to study the frustrated phases in copolymer particles [34]. In soft confinement, polymeric chains can self-assemble into a variety of particles with novel morphology. The simplest case is the self-assembly of homopolymers in soft confinement. If there are only one kind of homopolymers in soft confinement, homopolymers usually form a colloidal particle with smooth [20, 21] or textured [35] surface. A core-shell or janus particle appears in the soft confinement if there are two kinds of homopolymers [17, 22, 24, 36, 37]. And the effects of colloidal stabilizer and polymer end group on the morphology of nanoparticles are investigated [38, 39]. As a result, it is reasonable to deduce that multicompartment particle is observed in soft confinement, if there are many kinds of homopolymers. The self-assembly of AB diblock copolymers in soft confinement attracts scientist’s much interest, because it is the simplest case for copolymer. In the soft confinement with a strong 3
ACS Paragon Plus Environment
Langmuir
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Page 4 of 37
selective surface for one block of copolymer, diblock copolymers always form spherical nanoparticles, but the internal structure is novel and rich. Symmetric diblock copolymers form onion-like nanoparticle [3-5, 11, 12, 14-18, 22, 25, 27, 40]. In the contrary, asymmetrical diblock copolymers aggregate into perforated lamellae [13, 14], network [5], axially stacked toroids prolate ellipsoid [15], embedded cylinders [3, 5, 10, 15, 40], dispersed spheres particles [3, 15], as their symmetry is decreasing. In the soft confinement with a very weak selective or neutral surface, not only the shape of most nanoparticles is anisotropic instead of spherical, but also the internal structure is different. A case in point, symmetric AB diblock copolymers aggregate into janus, tennis ball, wheel, mushroom, screw, helix, branched helix sphere [23, 41], axially stacked lamellae prolate ellipsoidal particles[5, 14, 17, 18], or spherical [20-24], bud-like [14, 16-18] particles and sphere with onion-like inner structure and tapes surface [41], with enlarging confinement. In the other hand, asymmetric diblock copolymers form snowman (janus), dumbbells, triangles, tetrahedral and raspberry patchy particles as the scale of confinement is increasing [42]. Furthermore, as increasing the asymmetry of diblock copolymers, disordered lamellae [43], bicontinuous [5, 43], stacked toroids ellipsoidal, spiral cylinders [16], hexagonally-packed cylinders [22, 24], raspberry-like particles [42, 44] are observed in a relatively large confinement. In addition, morphological transformation is happened when the particle is treated by using thermal [45], microwave [46], and solvent annealing [18, 25, 47] or solvent swelling [31, 48, 49]. The blends of AB diblock copolymers and A or/and B homopolymers not only is a facile way to change the volume fraction of blocks, but also can enriches particle’s morphology which are not available in neat AB diblock copolymer system. Specifically, when homopolymers are shorter than block of copolymers much more (Lh
