Tetrablock Terpolymers Research Articles

Co-existing morphologies of lamellae and double arrays of cylinders by A1BA2C tetrablock terpolymer

Co-existing morphologies of lamellae and double arrays of cylinders by A1BA2C tetrablock terpolymer

Tetragonally and Rectangularly Packed Hierarchical Cylinders from A1 BA2 C Tetrablock Terpolymer.

Hierarchical cylindrical nanostructures with different diameters (or shapes) have received much attention because of potential applications to next-generation lithography or advanced optical devices. Here, weobserved, via small-angle X-ray scattering and transmission electron microscopy, tetragonally and rectanguarly packed hierachical cylindrical nanostructures by tailoring the volume fraction of polystyrene mid-block in polystyrene-b-polyisoprene-b-polystyrene-b-poly(2-vinylpyridine) tetrablock terpolymer (S1 IS2 V). P2VP becomes the main cylinder, while PI forms satellite cylinders surrounding the main P2VP cylinder. When the length of S2 block is relatively short, tetragonal arrangement of cylinders is observed. But, a rectanguar arrangement of cylinders is formed for larger S2 block. The experimentally observed hierarchical cylindrical nanostructures are in good agreement with the prediction by the self-consistent field theory. This article is protected by copyright. All rights reserved.

Frank–Kasper Phases in Block Polymers

The discovery of the Frank–Kasper σ phase in diblock copolymer and tetrablock terpolymer melts catalyzed a renewed interest over the past decade in understanding particle-forming phases in block polymer systems. This Perspective provides a concise overview of the Frank–Kasper phases seen to date in block polymers (A15, σ, and the C14 and C15 Laves phases) and mechanisms known to produce them: conformational asymmetry in neat diblock copolymer melts, interfacial segregation effects in diblock copolymer blends, particle swelling in diblock copolymer/homopolymer blends, and matrix segregation effects in neat tetrablock terpolymer melts. While a qualitative understanding of the emergence of Frank–Kasper phases in block polymer systems has been achieved, a number of outstanding questions remain, in particular those arising from the low degree of polymerization used in experiments, nonequilibrium effects during thermal processing, and the large design space available in blends and multiblock systems. This Perspective discusses potential avenues for future research related to these areas as well as overarching issues underlying the connections between Frank–Kasper phase formation in block polymers to other soft matter and metals.

Multidomain Helical Nanostructure by A1BA2C Tetrablock Terpolymer Self-Assembly.

Among many possible nanostructures in block copolymer self-assembly, helical nanostructures are particularly important because of potential applications for heterogeneous catalysts and plasmonic materials. In this work, we investigated, via small-angle X-ray scattering and transmission electron microscopy, the morphology of a polystyrene-block-polyisoprene-block-polystyrene-block-poly(2-vinylpyridine) (S1IS2V) tetrablock terpolymer. Very interestingly, when the volume fraction of each block was 0.685, 0.125, 0.060, and 0.130, respectively, a multidomain double-stranded helical nanostructure (MH2) was formed: P2VP chains became a core helix, and PI chains formed double-stranded helices surrounding the core helix. Core and double-stranded helices are connected by short PS2 chains, and PS1 chains become the matrix. The experimentally observed morphology is in good agreement with the prediction by self-consistent field theory. We believe that this multidomain helical structure will be pave the way to the creation of multifunctional helical structures for various applications such as metamaterials.

PEG-Based Methacrylate Tetrablock Terpolymers: How Does the Architecture Control the Gelation?

PEG-Based Methacrylate Tetrablock Terpolymers: How Does the Architecture Control the Gelation?

Data for Order and Disorder in ABCA′ Tetrablock Terpolymers

Self-consistent field theory calculations appearing in the paper, along with scripts for generating the plots of those data using Polymer Self Consistent Field (PSCF) code.

Order and Disorder in ABCA' Tetrablock Terpolymers.

Self-assembly of poly(styrene)-block-poly(isoprene)-block-poly(lactide)-block-poly(styrene) (PS-PI-PLA-PS' or SILS') tetrablock terpolymers, where the volume fractions of the first three blocks are nearly equivalent, was studied both experimentally and using the self-consistent field theory (SCFT). SCFT indicates that addition of the terminal PS' chain to a low-molecular-mass, hexagonally packed cylinders forming, SIL precursor can produce a disordered state due to preferential mixing of the polystyrene end-blocks with the PI and PLA midblocks in the SILS' tetrablock, alleviating the unfavorable contact between the highly incompatible PI and PLA segments. In contrast, SCFT predicts that higher-molar-mass triblock precursors will maintain an ordered morphology upon addition of the terminal PS' block due to stronger overall segregation strengths. These predictions were tested using three sets of SILS' polymers that were synthesized based on three precursor SIL triblock polymers differing in total molar mass (14, 30, and 47 kg mol-1) and varying the length of the terminal PS' chain. In the lowest-molar-mass set of tetrablock polymers, the shift from order to disorder was observed in the materials at ambient temperature as the molar mass of the terminal PS' block was increased, consistent with SCFT calculations. Disorder with longer S' chain lengths was not found in the two higher-molar-mass polymer sets; the medium-molar-mass set showed both microphase separation and long-range order based on transmission electron microscopy (TEM) and small-angle X-ray scattering (SAXS), while the largest of these block polymers microphase separated but showed limited long-range order. The combination of the experimental and theoretical results presented in this work provides insights into the self-assembly of ABCA'-type polymers and highlights potential complications that arise from frustration in accessing well-ordered materials.

Erratum to “Predicting the phase behavior of ABAC tetrablock terpolymers: Sensitivity to Flory–Huggins interaction parameters” [Polymer, 154 (2018), 305–314

This erratum corrects labels in Fig. 2(b) of the article, “Predicting the phase behavior of ABAC tetrablock terpolymers: Sensitivity to Flory–Huggins interaction parameters” [Polymer, 154 (2018), 305–314] and one statement in Subsection 2.4, “Comparison of Different Methods” (Page 308). The results, discussion, and conclusions of the article remain unchanged.

A New Cylindrical Structure from ABCBD Pentablock Quadpolymer Melt Studied by Monte Carlo Simulation

AbstractMorphology of AB0CB1D pentablock quadpolymers in melt is studied by Monte Carlo simulation, where B0 and B1 are the same polymer component. When the volume fractions of the two end‐blocks, φA, φD, and that of mid‐block, φC are all small, the B‐domain forms matrix phase, whereas the A‐, C‐, and D‐chains stay as cylindrical domains. A tetragonally packed cylindrical structure is observed in the composition range of 0.125 ≤ φC ≤ 0.188 at φA = φD = 0.125 and γ = 1.0, wherein γ is the volume fraction ratio of two B‐chains, that is, γ = φB0/φB1, defined as a symmetric factor. Another complex but periodic cylindrical structure is found at φA = φD = 0.125 and φC = 0.188 with quite wider γ range of 0.38 ≤ γ ≤ 0.64. By connecting D‐domains, this structure can be classified as the 3.3.4.3.4 Archimedean tiling, which is composed of imaginary regular triangles and squares. It should be noted that γ range of 3.3.4.3.4 phase is much wider for the present AB0CB1D pentablock quadpolymers than that for the AB0CB1 tetrablock terpolymers. In addition, the A‐domains have been found to display the periodic Cairo pentagonal tiling by drawing auxiliary connect lines.

Systematic study on evolution of self-assembly morphologies of CABC tetrablock terpolymers with varied segment lengths

The self-assembly structures of PEEA-PMMA-PGLMMA-PEEA CABC-type tetrablock terpolymers with a fixed length of the PGLMMA (red colour) segment and varied lengths of the PMMA (blue) and PEEA (green) segments were systematically studied.

Periodic and Aperiodic Tiling Patterns from a Tetrablock Terpolymer System of the A1BA2C Type.

Two tetrablock terpolymers of the S1IS2P type, where S, I, and P denote polystyrene, polyisoprene, and poly(2-vinylpyridine), respectively, were prepared anionically. S1IS2P-1 (S1/I/S2/P = 0.35/0.16/0.34/0.15, four numbers being volume fractions of S1, I, S2, and P block chains) has a structure with double hexagonal cylinders, while S1IS2P-2 (S1/I/S2/P = 0.47/0.15/0.22/0.16) has an unusual double tetragonal structure. Moreover, 13 binary blends were prepared from these two parent polymers. Among them, five blends with α(= φS1/φS2) covering the range 1.50 ≤ α ≤ 1.86 were confirmed to have a 3.3.4.3.4 Archimedean tiling structure, in which their P domains adopt five satellite I domains, while four blends with α covering the range 1.37 ≤ α ≤ 1.48 were revealed to be a quasicrystalline tiling structure with dodecagonal symmetry.

Self‐Assembly of Multiblock Copolymers

AbstractBlock copolymers (BCPs) are a subclass of soft matter extensively used in materials science and nanomedicine. They consist of two or more incompatible segments and are prone to self‐assemble into nanostructures with a characteristic size of 10–100 nm. BCPs thus naturally address the structural dimension between molecular and colloidal scales. This review gives a brief overview of recent developments in BCP self‐assembly under various conditions. Special emphasis is put on linear BCPs with three or more sequentially linked blocks, i. e. ABC triblock terpolymers, ABAC tetrablock terpolymers, and so on. We discuss their microphase separation in bulk, in the confinement of nanoemulsion droplets, and their hierarchical self‐assembly to multicompartment nanostructures in selective solvents. Regarding applications, block copolymers are widely used in templating and drug delivery, but their inherent asymmetry is also particularly useful for the synthesis of Janus nanoparticles.

Antimicrobial AgNPs composites of gelatin hydrogels crosslinked by ferrocene-containing tetrablock terpolymer

Abstract Redox-responsive ferrocene (Fc)-containing hydrogels have attracted increasing interest for their potential applications in materials science, biomedicine and catalysis. Herein, we report the synthesis of a novel polynorbornene-based tetrablock terpolymer containing consecutively aldehyde, Fc, and dentritic triethylene glycol and aldehyde groups in the side chain by the ring-opening metathesis polymerization with the aid of the 3rd generation Grubbs catalyst. Owing to the presence of Fc and triazole groups, this copolymer could be used as both reducing and stabilizing agents for the formation of silver nanoparticles (AgNPs). Also, this copolymer could be used as a crosslinking agent to fabricate gelatin hydrogels based on the Schiff's base reaction between the aldehyde groups and the side-chain amino groups of gelatin. Based on the above properties, the AgNPs composites of gelatin hydrogels were further successfully fabricated by blending this copolymer, gelatin and AgNO3 together or soaking this Fc-containing gelatin hydrogels into the AgNO3 solution, in which the AgI was in situ reduced into Ag0 by the Fc groups. Results of inhibition zone experiments confirmed the antibacterial activities of the obtained composites against both Escherichia coli and Staphylococcal aureus.

Stability of Two-Dimensional Dodecagonal Quasicrystalline Phase of Block Copolymers

Quasicrystalline (QC) phases have been observed in various condensed matter systems including self-assembling block copolymer (BCP) melts. Theoretical study of the thermodynamic stability of QC phases presents a long-standing unsolved problem because of the aperiodic nature of the structures. Here, we report a combination method to study the thermodynamic stability of two-dimensional dodecagonal quasicrystalline (DDQC) phase with both ideal tiling and random tiling patterns formed by ABCB tetrablock terpolymers. This method applies the self-consistent field theory coupled with the Stampfli self-similarity construction to accurately calculate the free energy of the periodic DDQC approximants and then uses a cluster model to predict the stability of aperiodic DDQC phase. Surprisingly, we find a stable DDQC approximant but metastable ideal tiling DDQC structures. Moreover, the random tiling DDQC structures as a mesoscopic coexistence of two neighboring periodic substructures of DDQC might become stable.

Predicting the phase behavior of ABAC tetrablock terpolymers: Sensitivity to Flory–Huggins interaction parameters

Abstract Self-consistent field theory (SCFT) is a powerful tool for discovering new nanostructures in self-assembling block polymers. However, the reliability of the resulting predictions depend strongly on the Flory-Huggins interaction parameters χij used to quantify the excess free energy of mixing of different blocks i and j arising from segment-segment interactions. The problem is especially significant for multiblock polymers, owing to the multitude of χij parameters and the sensitivity of the resulting phase behavior when the χij do not differ substantially for different block pairs. To illuminate this issue, we examine how the SCFT-predicted phase behavior of a poly(styrene)-b-poly(isoprene)-b-poly(styrene)'-b-poly(ethylene oxide) (SIS'O) tetrablock terpolymer changes depending on the method used to estimate the trio of χij parameters for this chemistry. SIS'O is an ideal model system for our purposes, as it exhibits a large number of poly(ethylene oxide) sphere-forming phases, emerging from the segregation of the poly(ethylene oxide) block due to the relatively high values of χSO and χIO, accompanied by subtle matrix segregation effects arising due to the smaller χIS between poly(isoprene) and poly(styrene). We first use χIS, χIO, and χSO available in the literature that were estimated using mean-field theory order–disorder transitions of the relevant diblock polymers. As this method is expected to lead to significant errors in χij that propagate into the SCFT predictions, we also consider two fluctuation-corrected approaches to extract χij from diblock polymer data, namely (i) fitting the order-disorder transition temperature to that predicted by molecular dynamics simulations and (ii) renormalized one-loop theory predictions for the structure factor of the disordered state. While even the fluctuation-corrected χ parameters do not lead to SCFT phase behavior that exactly matches experiments, the SCFT calculations using the molecular dynamics-fitted χ parameters correctly predict stable Frank–Kasper A15 and σ phases. The results presented here highlight the challenges in predictively modeling the phase behavior of multiblock polymers using SCFT, a critical task for the discovery of new multiblock polymer materials.

Thermoresponsive Tetrablock Terpolymers: Effect of Architecture and Composition on Gelling Behavior

Thermoresponsive gels are an exciting class of materials with many bioapplications, like tissue engineering and drug delivery, but they are also used in formulation industry and 3-D printing. For these applications to be feasible, the gelation temperature must be tailored. Here, it is reported how the gelation temperature is affected and can be tailored by varying the architecture of tetrablock terpolymers. Specifically, 15 copolymers based on penta(ethylene glycol) methyl ether methacrylate (PEGMA, A block), n-butyl methacrylate (BuMA, B block), and the thermoresponsive 2-(dimethylamino)ethyl methacrylate (DMAEMA, C block) were synthesized using group transfer polymerization. Nine tetrablock copolymers of varying architectures, and one triblock copolymer for comparison, with constant molar mass and composition were fabricated. Specifically, the polymers that were investigated are (i) three polymers that contain two A blocks (ABCA, ABAC, and ACAB), (ii) three polymers that contain two B blocks (BACB, BABC...

Four‐Phase Morphologies in Blends of ABC and BAC Triblock Terpolymers

AbstractIt is investigated how binary blends of two asymmetric triblock terpolymers with the same type of monomers but different block sequences (ABC, BAC) and different block lengths lead to three new ABAC tetrablock terpolymer like morphologies. This study ascribes the formation of four microphases to a parallel chain orientation during the blend process. Because of the resultant spatial superposition, the B‐blocks of both block copolymers can mix into each other as well as both C‐blocks, whereas both A‐blocks form independent microphases. The self‐assembly of nine blends are studied. Their morphologies depend on the blending ratio and are monitored by transmission electron microscopy and small‐angle X‐ray scattering. Besides single morphologies, also coexisting morphologies are obtained, indicating that different superstructures are stable within finite compositional ranges of the blends. This work demonstrates that blending of triblock terpolymers with different block sequence is another interesting way in the huge area of morphological engineering by blending of block copolymers, leading to new and even complex, tailored nanostructures.

Controlled synthesis of ABCA' tetrablock terpolymers

Polystyrene-block-polyisoprene-block-polylactide-block-polystyrene tetrablock terpolymers were synthesized via sequential anionic, ring-opening, and reversible addition-fragmentation chain-transfer polymerizations. The optimized synthesis of these ABCA' tetrablock terpolymers yields polymers with low molar mass dispersity and allowed for straightforward and independent tuning of the Mn for each block. We determined that careful processing of these polymers was necessary to avoid deleterious side reactions during solvent casting or annealing. Preliminary microscopy data demonstrated the ability of these polymers to form non-spherical domains of the B and C blocks. The 26 tetrablock terpolymers synthesized will enable detailed studies of the ABCA' morphological map.

Planet-Satellite Micellar Superstructures Formed by ABCB Terpolymers in Solution.

The occurrence and relative stability of planet-satellite nanostructures, composed of a host micelle (the planet) accompanied by a number of guest micelles (the satellites), in ABCB tetrablock terpolymer solutions are studied using the polymeric self-consistent field theory and dissipative particle dynamics simulations. The theoretical results demonstrate that the self-assembly of the ABCB tetrablock terpolymers with solvophobic A- and C-blocks and solvophilic B-blocks could lead to the formation of various planet-satellite superstructures, where the planet and satellites are composed of the A- and C-blocks, respectively. Furthermore, the number of satellites is controlled by the ratio of the two B-blocks. The arrangement of the satellites surrounding the planet resembles the solution of the well-known Thomson's problem concerning the optimum arrangement of a given number of electrons on a sphere. Besides providing a facile route to engineering novel multicompartment micelles with planet-satellite superstructures for potential advanced applications, the study strengthens the prospect that multiblock copolymers could become a useful platform for the fabrication of complex nanostructures.

SISO-based hot-melt pressure-sensitive adhesives for transdermal delivery of hydrophilic drugs

Abstract A monomer-activated anionic polymerization approach was utilized to synthesize poly(styrene-b-isoprene-b-styrene-b-ethylene oxide) tetrablock terpolymers (SISO), which were melt-mixed with tackifiers and plasticizer to develop polar SISO-based hot-melt pressure-sensitive adhesives (HMPSAs) for transdermal delivery of hydrophilic drugs. Their hydrophilic performance was characterized using contact angle analysis. Their adhesive performances were measured in terms of 180° peel strength and holding power. In vitro drug release experiments were carried out using a modified Franz type horizontal diffusion cell, in which geniposide was chosen as a hydrophilic model drug. The results show that poly(ethylene oxide) (PEG) blocks exhibit substantial effects on adhesive performance and the release behavior of the model drug. The shorter PEG molecular chains enhance adhesive performance and the cumulative release rate of the model drug in the SISO-based HMPSAs. The longer PEG molecular chains tend to crystallize. Their crystallization structures have negative effects on adhesive performance and limit the dissolution and diffusion of drugs in the SISO-based HMPSAs. Therefore, appropriate PEG molecular chains are required to fabricate SISO-based HMPSAs with excellent adhesive performance for transdermal delivery of hydrophilic drugs.