Polymers

Research

22 pages, 6273 KiB

Open AccessArticle

Self-Assembled Amphiphilic Fluorinated Random Copolymers for the Encapsulation and Release of the Hydrophobic Combretastatin A-4 Drug

by Matteo Calosi, Elisa Guazzelli, Simona Braccini, Marco Lessi, Fabio Bellina, Giancarlo Galli and Elisa Martinelli

Polymers 2022, 14(4), 774; https://doi.org/10.3390/polym14040774 - 16 Feb 2022

Cited by 7 | Viewed by 2895

Abstract

Water-soluble amphiphilic random copolymers composed of tri(ethylene glycol) methacrylate (TEGMA) or poly(ethylene glycol) methyl ether methacrylate (PEGMA) and perfluorohexylethyl acrylate (FA) were synthesized by ARGET-ATRP, and their self-assembling and thermoresponsive behavior in water was studied by dynamic light scattering (DLS) and UV-vis spectroscopy. [...] Read more.

Water-soluble amphiphilic random copolymers composed of tri(ethylene glycol) methacrylate (TEGMA) or poly(ethylene glycol) methyl ether methacrylate (PEGMA) and perfluorohexylethyl acrylate (FA) were synthesized by ARGET-ATRP, and their self-assembling and thermoresponsive behavior in water was studied by dynamic light scattering (DLS) and UV-vis spectroscopy. The copolymer ability to self-fold in single-chain nano-sized structures (unimer micelles) in aqueous solutions was exploited to encapsulate Combretastatin A-4 (CA-4), which is a very hydrophobic anticancer drug. The cloud point temperature (T_cp) was found to linearly decrease with increasing drug concentration in the drug/copolymer system. Moreover, while CA-4 was preferentially incorporated into the unimer micelles of TEGMA-ran-FA, the drug was found to induce multi-chain, submicro-sized aggregation of PEGMA-ran-FA. Anyway, the encapsulation efficiency was very high (≥81%) for both copolymers. The drug release was evaluated in PBS aqueous solutions both below and above T_cp for TEGMA-ran-FA copolymer and below T_cp, but at two different drug loadings, for PEGMA-ran-FA copolymer. In any case, the release kinetics presented similar profiles, characterized by linear trends up to ≈10–13 h and ≈7 h for TEGMA-ran-FA and PEGMA-ran-FA, respectively. Then, the release rate decreased, reaching a plateau. The release from TEGMA-ran-FA was moderately faster above T_cp than below T_cp, suggesting that copolymer thermoresponsiveness increased the release rate, which occurred anyway by diffusion below T_cp. Cytotoxicity tests were carried out on copolymer solutions in a wide concentration range (5–60 mg/mL) at 37 °C by using Balb/3T3 clone A31 cells. Interestingly, it was found that the concentration-dependent micro-sized aggregation of the amphiphilic random copolymers above T_cp caused a sort of “cellular asphyxiation” with a loss of cell viability clearly visible for TEGMA-ran-FA solutions (T_cp below 37 °C) with higher copolymer concentrations. On the other hand, cells in contact with the analogous PEGMA-ran-FA (T_cp above 37 °C) presented a very good viability (≥75%) with respect to the control at any given concentration. Full article

(This article belongs to the Special Issue Self-Assembly of Block Copolymers: Experiment and Modelling)

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17 pages, 4750 KiB

Open AccessArticle

Organosilica-Modified Multiblock Copolymers for Membrane Gas Separation

by Ilsiya M. Davletbaeva, Alexander Yu. Alentiev, Zulfiya Z. Faizulina, Ilnaz I. Zaripov, Roman Yu. Nikiforov, Victor V. Parfenov and Alexander V. Arkhipov

Polymers 2021, 13(20), 3579; https://doi.org/10.3390/polym13203579 - 17 Oct 2021

Cited by 3 | Viewed by 2054

Abstract

Organosubstituted silica derivatives were synthesized and investigated as modifiers of block copolymers based on macroinitiator and 2,4-toluene diisocyanate. A peculiarity of the modified block copolymers is the existence in their structure of coplanar rigid polyisocyanate blocks of acetal nature (O-polyisocyanates). Organosubstituted silica derivatives [...] Read more.

Organosubstituted silica derivatives were synthesized and investigated as modifiers of block copolymers based on macroinitiator and 2,4-toluene diisocyanate. A peculiarity of the modified block copolymers is the existence in their structure of coplanar rigid polyisocyanate blocks of acetal nature (O-polyisocyanates). Organosubstituted silica derivatives have a non-additive effect on high-temperature relaxation and α-transitions of modified polymers and exhibit the ability to influence the supramolecular structure of block copolymers. The use of the developed modifiers leads to a change in the gas transport properties of block copolymers. The increase of the permeability coefficients is due to the increase of the diffusion coefficients. At the same time, the gas solubility coefficients do not change. An increase in the ideal selectivity for a number of gas pairs is observed. An increase in the selectivity for the CO₂/N₂ gas pair (from 25 to 39) by 1.5 times demonstrates the promising use of this material for flue gases separation. Full article

(This article belongs to the Special Issue Self-Assembly of Block Copolymers: Experiment and Modelling)

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15 pages, 3633 KiB

Open AccessArticle

Self-Assembly of Bottlebrush Block Copolymers in Selective Solvent: Micellar Structures

by Inna O. Lebedeva, Ekaterina B. Zhulina and Oleg V. Borisov

Polymers 2021, 13(9), 1351; https://doi.org/10.3390/polym13091351 - 21 Apr 2021

Cited by 10 | Viewed by 2425

Abstract

Block copolymers comprising chemically different bottlebrush blocks can self-assemble in selective solvents giving rise to micellar-like solution nanostructures. The self-consistent field theoretical approach is used for predicting relation between architectural parameters of both bottlebrush blocks (polymerization degrees of the main and side chains, [...] Read more.

Block copolymers comprising chemically different bottlebrush blocks can self-assemble in selective solvents giving rise to micellar-like solution nanostructures. The self-consistent field theoretical approach is used for predicting relation between architectural parameters of both bottlebrush blocks (polymerization degrees of the main and side chains, density of grafting of the side chains to the backbone) and structural properties of micelles as well as critical micelle concentration (CMC). As predicted by the theory, replacement of linear blocks by bottlebrush ones with the same degrees of polymerization results in a decrease in the micellar core size (in aggregation number) and extension of the corona, whereas the CMC increases. These theoretical findings are in good agreement with results of computer simulations. Full article

(This article belongs to the Special Issue Self-Assembly of Block Copolymers: Experiment and Modelling)

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22 pages, 4448 KiB

Open AccessArticle

Mikto-Arm Stars as Soft-Patchy Particles: From Building Blocks to Mesoscopic Structures

by Petra Bačová, Dimitris G. Mintis, Eirini Gkolfi and Vagelis Harmandaris

Polymers 2021, 13(7), 1114; https://doi.org/10.3390/polym13071114 - 1 Apr 2021

Cited by 1 | Viewed by 2297

Abstract

We present an atomistic molecular dynamics study of self-assembled mikto-arm stars, which resemble patchy-like particles. By increasing the number of stars in the system, we propose a systematic way of examining the mutual orientation of these fully penetrable patchy-like objects. The individual stars [...] Read more.

We present an atomistic molecular dynamics study of self-assembled mikto-arm stars, which resemble patchy-like particles. By increasing the number of stars in the system, we propose a systematic way of examining the mutual orientation of these fully penetrable patchy-like objects. The individual stars maintain their patchy-like morphology when creating a mesoscopic (macromolecular) self-assembled object of more than three stars. The self-assembly of mikto-arm stars does not lead to a deformation of the stars, and their shape remains spherical. We identified characteristic sub-units in the self-assembled structure, differing by the mutual orientation of the nearest neighbor stars. The current work aims to elucidate the possible arrangements of the realistic, fully penetrable patchy particles in polymer matrix and to serve as a model system for further studies of nanostructured materials or all-polymer nanocomposites using the mikto-arm stars as building blocks. Full article

(This article belongs to the Special Issue Self-Assembly of Block Copolymers: Experiment and Modelling)

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15 pages, 1962 KiB

Open AccessArticle

The Micellization of Well-Defined Single Graft Copolymers in Block Copolymer/Homopolymer Blends

by Eleni Pavlopoulou, Kiriaki Chrissopoulou, Stergios Pispas, Nikos Hadjichristidis and Spiros H. Anastasiadis

Polymers 2021, 13(5), 833; https://doi.org/10.3390/polym13050833 - 9 Mar 2021

Cited by 4 | Viewed by 2689

Abstract

A series of well-defined (polyisoprene)₂(polystyrene), I₂S, single graft copolymers with similar total molecular weights but different compositions, f_PS, were blended with a low molecular weight polyisoprene homopolymer matrix at a constant concentration 2 wt%, and the micellar [...] Read more.

A series of well-defined (polyisoprene)₂(polystyrene), I₂S, single graft copolymers with similar total molecular weights but different compositions, f_PS, were blended with a low molecular weight polyisoprene homopolymer matrix at a constant concentration 2 wt%, and the micellar characteristics were studied by small-angle x-ray scattering. To investigate the effect of macromolecular architecture on the formation and characteristics of micelles, the results on the single graft copolymers were compared with those of the corresponding linear polystyrene-b-polyisoprene diblock copolymers, SI. The comparison reveals that the polystyrene core chains are more stretched in the case of graft copolymer micelles. Stretching turned out to be purely a result of the architecture due to the second polyisoprene block in the corona. The micellization of a (polystyrene)₂(polyisoprene), S₂I, graft copolymer was also studied, and the comparison with the results of the corresponding I₂S and SI copolymers emphasizes the need for a critical core volume rather than a critical length of the core-forming block, in order to have stable micelles. Finally, the absence of micellization in the case of the I₂S copolymer with the highest polystyrene volume fraction is discussed. For this sample, macrophase separation occurs, with polyisoprene cylinders formed in the copolymer-rich domains of the phase-separated blends. Full article

(This article belongs to the Special Issue Self-Assembly of Block Copolymers: Experiment and Modelling)

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10 pages, 2101 KiB

Open AccessArticle

High Performance Field-Effect Transistors Based on Partially Suspended 2D Materials via Block Copolymer Lithography

by Simon Kim, Su Eon Lee, Jun Hyun Park, Jin Yong Shin, Bom Lee, Heo Yeon Lim, Young Taek Oh, Jun Pyo Hwang, Seung Won Seon, Seung Hee Kim, Tae Sang Yu and Bong Hoon Kim

Polymers 2021, 13(4), 566; https://doi.org/10.3390/polym13040566 - 14 Feb 2021

Cited by 2 | Viewed by 3320

Abstract

Although various two-dimensional (2D) materials hold great promise in next generation electronic devices, there are many challenges to overcome to be used in practical applications. One of them is the substrate effect, which directly affects the device performance. The large interfacial area and [...] Read more.

Although various two-dimensional (2D) materials hold great promise in next generation electronic devices, there are many challenges to overcome to be used in practical applications. One of them is the substrate effect, which directly affects the device performance. The large interfacial area and interaction between 2D materials and substrate significantly deteriorate the device performance. Several top-down approaches have been suggested to solve the problem. Unfortunately, however, they have some drawbacks such as a complicated fabrication process, a high production cost, or a poor mechanical property. Here, we suggest the partially suspended 2D materials-based field-effect transistors (FETs) by introducing block copolymer (BCP) lithography to fabricate the substrate effect-free 2D electronic devices. A wide range of nanometer size holes (diameter = 31~43 nm) is successfully realized with a BCP self-assembly nanopatterning process. With this approach, the interaction mechanism between active 2D materials and substrate is elucidated by precisely measuring the device performance at varied feature size. Our strategy can be widely applied to fabricate 2D materials-based high performance electronic, optoelectronic, and energy devices using a versatile self-assembly nanopatterning process. Full article

(This article belongs to the Special Issue Self-Assembly of Block Copolymers: Experiment and Modelling)

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10 pages, 2566 KiB

Open AccessArticle

Hierarchical Self-Assembly of Thickness-Modulated Block Copolymer Thin Films for Controlling Nanodomain Orientations inside Bare Silicon Trenches

by Jin Yong Shin, Young Taek Oh, Simon Kim, Hoe Yeon Lim, Bom Lee, Young Chun Ko, Shin Park, Seung Won Seon, Se Gi Lee, Seung Soo Mun and Bong Hoon Kim

Polymers 2021, 13(4), 553; https://doi.org/10.3390/polym13040553 - 13 Feb 2021

Cited by 4 | Viewed by 3410

Abstract

We study the orientation and ordering of nanodomains of a thickness-modulated lamellar block copolymer (BCP) thin film at each thickness region inside a topological nano/micropattern of bare silicon wafers without chemical pretreatments. With precise control of the thickness gradient of a BCP thin [...] Read more.

We study the orientation and ordering of nanodomains of a thickness-modulated lamellar block copolymer (BCP) thin film at each thickness region inside a topological nano/micropattern of bare silicon wafers without chemical pretreatments. With precise control of the thickness gradient of a BCP thin film and the width of a bare silicon trench, we successfully demonstrate (i) perfectly oriented lamellar nanodomains, (ii) pseudocylindrical nanopatterns as periodically aligned defects from the lamellar BCP thin film, and (iii) half-cylindrical nanostructure arrays leveraged by a trench sidewall with the strong preferential wetting of the PMMA block of the BCP. Our strategy is simple, efficient, and has an advantage in fabricating diverse nanopatterns simultaneously compared to conventional BCP lithography utilizing chemical pretreatments, such as a polymer brush or a self-assembled monolayer (SAM). The proposed self-assembly nanopatterning process can be used in energy devices and biodevices requiring various nanopatterns on the same device and as next-generation nanofabrication processes with minimized fabrication steps for low-cost manufacturing techniques. Full article

(This article belongs to the Special Issue Self-Assembly of Block Copolymers: Experiment and Modelling)

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17 pages, 9441 KiB

Open AccessEditor’s ChoiceArticle

Solubilization of Charged Porphyrins in Interpolyelectrolyte Complexes: A Computer Study

by Karel Šindelka, Zuzana Limpouchová and Karel Procházka

Polymers 2021, 13(4), 502; https://doi.org/10.3390/polym13040502 - 6 Feb 2021

Cited by 5 | Viewed by 2058

Abstract

Using coarse-grained dissipative particle dynamics (DPD) with explicit electrostatics, we performed (i) an extensive series of simulations of the electrostatic co-assembly of asymmetric oppositely charged copolymers composed of one (either positively or negatively charged) polyelectrolyte (PE) block A and one water-soluble block B [...] Read more.

Using coarse-grained dissipative particle dynamics (DPD) with explicit electrostatics, we performed (i) an extensive series of simulations of the electrostatic co-assembly of asymmetric oppositely charged copolymers composed of one (either positively or negatively charged) polyelectrolyte (PE) block A and one water-soluble block B and (ii) studied the solubilization of positively charged porphyrin derivatives (P

^{+}

) in the interpolyelectrolyte complex (IPEC) cores of co-assembled nanoparticles. We studied the stoichiometric mixtures of 137 A

_{10}^{+}

B

_{25}

and 137 A

_{10}^{-}

B

_{25}

chains with moderately hydrophobic A blocks (DPD interaction parameter

a_{A S} = 35

) and hydrophilic B blocks (

a_{B S} = 25

) with 10 to 120 P

^{+}

added (

a_{PS} = 39

). The P

^{+}

interactions with other components were set to match literature information on their limited solubility and aggregation behavior. The study shows that the moderately soluble P

^{+}

molecules easily solubilize in IPEC cores, where they partly replace PE

^{+}

and electrostatically crosslink PE

^{-}

blocks. As the large P

^{+}

rings are apt to aggregate, P

^{+}

molecules aggregate in IPEC cores. The aggregation, which starts at very low loadings, is promoted by increasing the number of P

^{+}

in the mixture. The positively charged copolymers repelled from the central part of IPEC core partially concentrate at the core-shell interface and partially escape into bulk solvent depending on the amount of P

^{+}

in the mixture and on their association number,

A_{S}

. If

A_{S}

is lower than the ensemble average

{⟨ A_{S} ⟩}_{n}

, the copolymer chains released from IPEC preferentially concentrate at the core-shell interface, thus increasing

A_{S}

, which approaches

{⟨ A_{S} ⟩}_{n}

. If

A_{S} > {⟨ A_{S} ⟩}_{n}

, they escape into the bulk solvent. Full article

(This article belongs to the Special Issue Self-Assembly of Block Copolymers: Experiment and Modelling)

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