Copolymer Architecture Research Articles

Antifouling Immunomodulatory Copolymer Architectures That Inhibit the Fibrosis of Implants.

Immune reactions to medical implants often lead to encapsulation by fibrotic tissue and impaired device function. This process is thought to initiate by protein adsorption, which enables immune cells to attach and mount an inflammatory response. Previously, several antifibrotic materials have been either designed to reduce protein adsorption or discovered via high-throughput screens (HTS) to favorably regulate inflammation. The present work introduces antifouling immunomodulatory (AIM) copolymer coatings, which combine both strategies to effectively enhanceimplant protection. AIM copolymers synergistically integrate zwitterionic moieties to resist protein fouling, HTS-derived antifibrotics for immunomodulation, and silane monomers for grafting to diverse substrates including elastomers, ceramics, and metals. Interestingly, simply combining these monomers into conventional random or block copolymer architectures yielded no significant advantage over homopolymers. By contrast, an unusual polymer chain architecture - a zwitterionic block flanked by a mixed zwitterionic immunomodulatory segment - showed superior fibrosis resistance in both peritoneal and subcutaneous sites over one month in immunocompetent mice. This architecture also improved the performance of two different HTS-derived antifibrotic monomers, suggesting that tailoring AIM architectures may broadly complement immunomodulatory chemistries and provide a versatile approach to improving implant longevity.

Automated chain architecture screening for discovery of block copolymer assembly with graph enhanced self-consistent field theory

The diverse chain architectures of block copolymers makes them important for exploring new self-assembly, but poses significant challenges for identifying the stability windows of desired mesophases within the vast parameter space. Here, we present an automated workflow for screening chain architectures to discover new self-assembly. Utilizing graph-enhanced self-consistent field theory complemented by a scattering-based identification strategy, our approach enables the automated computation of arbitrary chain architectures and their phase behavior. This framework successfully identifies stable windows for a novel PtS phase in AB-type block copolymer melts, with two distinct chain architectures emerging from the screening process. Our findings demonstrate the utility of this method in stabilizing desired self-assembly and exploring new mesophases. The flexibility of our approach allows for straightforward extension to multi-species and multi-component systems and further integration with metaheuristic optimization techniques to enhance its potential for materials design.

Structural Engineering of Cationic Block Copolymer Architectures for Selective Breaching of Prokaryotic and Eukaryotic Biological Species.

Positively charged antimicrobial polymers are known to cause severe damage to biological systems, and thus synthetic strategies are urgently required to design next-generation nontoxic cationic macromolecular architectures for healthcare applications. Here, we report a structural-engineering strategy to build cationic linear and star-block copolymer nanoarchitectures having identical chemical composition, molar mass, nanoparticle size, and positive surface charge, yet they differ distinctly in their biological action in breaching prokaryotic species such as E. coli (Gram-negative bacteria) without affecting eukaryotic species like red-blood and mammalian cells. For this purpose, linear and star-block structures are built on a polycaprolactone biodegradable platform having an imidazolium positive handle. Under physiological conditions, the linear architecture exhibits toxicity indiscriminately to all biological species, whereas its star counterpart is remarkably selective in membrane breaching action toward bacteria while maintaining inertness toward eukaryotic species. Confocal microscopy analysis of HPTS fluorescent dye-loaded star-polymer nanoparticles substantiated their antimicrobial action in E. coli. Tissue-penetrable near-infrared fluorescent dye (IR-780) loaded NP aided the in vivo biodistribution analysis and ex vivo quantification of cationic species' accumulations in vital organs in mice. Azithromycin, a clinical water-insoluble macrolide, is delivered from the star platform to accomplish synergistic antimicrobial activity by the combination of bactericidal-bacteriostatic action of the polymer carrier and drug together in a single system.

Enhancing the Biomimetic Mechanics of Bottlebrush Graft-Copolymers through Selective Solvent Annealing.

Self-assembled networks of bottlebrush copolymers are promising materials for biomedical applications due to a unique combination of ultra-softness and strain-adaptive stiffening, characteristic of soft biological tissues. Transitioning from ABA linear-brush-linear triblock copolymers to A-g-B bottlebrush graft copolymer architectures allows significant increasing the mechanical strength of thermoplastic elastomers. Using real-time synchrotron small-angle X-ray scattering, it is shown that annealing of A-g-B elastomers in a selective solvent for the linear A blocks allows for substantial network reconfiguration, resulting in an increase of both the A domain size and the distance between the domains. The corresponding increases in the aggregation number and extension of bottlebrush strands lead to a significant increase of the strain-stiffening parameter up to 0.7, approaching values characteristic of the brain and skin tissues. Network reconfiguration without disassembly is an efficient approach to adjusting the mechanical performance of tissue-mimetic materials to meet the needs of diverse biomedical applications.

Tailoring copolymer architectures and macromolecular interactions for enhanced nanotherapeutic delivery: A design-by-architecture approach

Amphiphilic copolymers with precise macromolecular topologies are crucial in nanomedicine for enhancing drug delivery by improving solubilization, stabilization, and therapeutic efficacy on target tissues. This study employs a design-by-architecture approach to identify factors influencing interactions between synthesized macromolecules and biological systems for optimal drug nanodelivery. Copolymers combining poly(ε-caprolactone) blocks and poly(polyethylene glycol methacrylate) or poly(glycerol methacrylate), were synthesized to investigate how architectural adjustments impact self-assembly, nanoparticle size, drug loading, and biomolecule interactions. Linear and brush block copolymers with varied block lengths were studied for their self-assembly behavior in aqueous environments. Both copolymer types formed smaller nanoparticles with extended hydrophilic blocks, with brush block copolymers showing superior performance due to their peculiar macromolecular architecture. Incorporating ‘clickable’ glycidyl units within the hydrophilic block minimally affected particle size. Controlled functionalization with thiol groups resulted in stable nanoparticles with enhanced size reduction and mucoadhesive properties, potentially improving targeted drug delivery and therapeutic effects.

Visible light-driven photoreforming of polystyrene segmented glycopolymer architectures for enhanced hydrogen generation

In this report, a series of polystyrene segmented new glycopolymer architectures are synthesized, which are utilized in the photoreforming process to achieve a remarkable rate of hydrogen production. The primary building blocks of mono-, bi-, and tetra-functional photo-iniferter were employed in the RAFT polymerization process to design a series of block copolymer architectures using styrene and acetylated glucose methacrylate monomers. Acetylated polymer architectures exhibited higher thermal stability compared to deacetylated polymers. Deacetylated polymers showed lower Tg values than the acetylated polymers. In addition, a wide range of Tg values (55–96 °C) and variations in the Tm values of the acetylated polymers indicate the dependence on the nature of the pendant unit and macromolecular architecture. The deacetylated macromolecule, 1A-PS-b-PGMD diblock copolymer exhibits a hydrogen generation rate of ∼753 μmol/g/h with an AQY of ∼1.84% compared to that of the polystyrene segment alone (53 μmol/g/h, AQY of ∼0.02%). Within the range of possible synthesized glycopolymer architectures, linear and glucose-based triblock glycopolymers show promising activity. The kinetics of the water-splitting reaction are influenced by adjustments to both the solution's pH and the hydrophilicity of the glycomacromolecular chains.

(Invited) Nano-Characterization of the Internal Morphology of Polymer Electrolyte Membranes with Cryogenic Scanning Transmission Electron Microscopy

Polymer membranes play important roles in electrochemical devices such as polymer electrolyte fuel cells. In recent years, there has been a growing interest in alkaline anion exchange membrane (AAEM) fuel cells as the alkaline environment offers a potential low-cost alternative to commercial proton exchange membrane (PEM) fuel cells [1]. Nonetheless, optimization of polymer properties such as ion conductivity and mechanical durability is still necessary to achieve commercially viable AAEM based fuel cells. Often, semicrystalline polymer backbones are selected for AAEM design, aiming to replicate the exceptional performance of Nafion in PEM fuel cells where the crystalline domains are believed to act as cross-linkers, mitigating excessive water uptake and mechanical degradation [2,3].Characterizing the local polymer morphology at the nanoscale is a crucial step in understanding how to optimize the design of AAEMs with enhanced durability and ion conductivity. Imaging polymers using conventional transmission electron microscopy (TEM) techniques is challenging however, due to their inherently-high beam sensitivity and low image contrast. Here, we demonstrate nanometer-resolution mapping of the ordering in polymer electrolyte membranes using cryogenic four-dimensional scanning transmission electron microscopy (cryo-4D-STEM). Conventionally used for mapping inorganic crystalline materials, the 4D-STEM technique has more recently also found applications in mapping semicrystalline, soft materials as well [4,5]. Here, using a model system of semicrystalline hydrogenated polynorbornene (hPN) AAEMs [6], we demonstrate the effects of polymer synthesis including molecular weight and thermal history on crystalline morphology and in turn on the polymer performance. Further, we compare the crystalline architecture of the hPN copolymers to that of Nafion 212 (Figure 1). Our results suggest that polymers with homogeneously distributed, nanometer-size crystalline domains lead to improved water management, a property directly related to the mechanical integrity of the polymer, with possible impacts on ion conductivity. More broadly, the results give new insights into how we can tune AAEM design in order to improve their performance.[1] Dekel, Journal of Power Sources, 375, 158-169. (2018).[2] Yang, et al. Chemical Reviews, 122(6), 6117-6321. (2022).[3] Mauritz & Moore, Chemical reviews, 104(10), 4535-4586. (2004).[4] Panova, et al. Nature materials, 18(8), 860-865. (2019).[5] Bustillo, et al. Accounts of chemical research, 54(11), 2543-2551. (2021).[6] Treichel, et al. Macromolecules, 53(19), 8509-8518. (2020).Figure 1: Cryo-4D-STEM crystallinity maps of hPN-co-iPrMe copolymers with varying syntheses and Nafion 212. We observe improvement in the water management of the copolymer membranes as the crystalline domains are reduced in volume and distributed homogeneously. The chemical structures of the polymers are listed below the crystallinity maps. Figure 1

New Copolymer Architecture for Mixed Matrix Membranes with High Loadings of ZIF-8 for Enhanced CO2 Permeability

New Copolymer Architecture for Mixed Matrix Membranes with High Loadings of ZIF-8 for Enhanced CO₂ Permeability

Enhancing Polymer Blend Compatibility with Linear and Complex Star Copolymer Architectures: A Monte Carlo Simulation Study with the Bond Fluctuation Model.

A Monte Carlo study of the compatibilization of A/B polymer blends has been performed using the bond fluctuation model. The considered compatibilizers are copolymer molecules composed of A and B blocks. Different types of copolymer structures have been included, namely, linear diblock and 4-block alternating copolymers, star block copolymers, miktoarm stars, and zipper stars. Zipper stars are composed of two arms of diblock copolymers arranged in alternate order (AB and BA) from the central unit, along with two homogeneous arms of A and B units. The compatibilization performance has been characterized by analyzing the equilibration of repulsion energy, the simulated scattering intensity obtained with opposite refractive indices for A and B, the profiles along a coordinate axis, the radial distribution functions, and the compatibilizer aggregation numbers. According to the results, linear alternate block copolymers, star block copolymers, and zipper stars exhibit significantly better compatibilization, with zipper stars showing slightly but consistently better performance.

Impact of polyglycidol block architecture in polystyrene-b-polyglycidol copolymers on the properties of thin films and protein adsorption

The effect of the architecture of amphiphilic polystyrene-b-polyglycidol and polystyrene-b-(polyglycidol-g-polyglycidol) copolymers on their behavior in thin films and interaction with the protein has been studied. The properties of the copolymer films surface were investigated before and after incubation in water and aqueous solution of PBS buffer. Surface sensitive techniques: time-of-flight secondary ion mass spectrometry, atomic force microscopy, and contact angle measurements show the differences in film surfaces behavior depending on the copolymer architecture. It was found that exposure of the coil-brush copolymer to an aqueous solution reoriented the PGL segments, changing the properties of the surface layer. Greater exposure of antifouling PGL chains at the surface of the copolymer film modified the interaction with bovine serum albumin, significantly reducing its adsorption. In contrast, no changes in the orientation of the PGL chains were observed after incubation of the copolymer films in an aqueous solution of protein in PBS buffer. This suggests that protein adsorption to the thin copolymer film blocks the conformational changes of the copolymer chains and reduces their mobility under the protein molecules.

Effect of Block Copolymer Self-Assembly on Phase Separation in Photopolymerizable Epoxy Blends.

Directing self-assembly of photopolymerizable systems is advantageous for controlling polymer nanostructure and material properties, but developing techniques for inducing ordered structure remains challenging. In this work, well-defined diblock or random copolymers were incorporated into cationic photopolymerizable epoxy systems to investigate the impact of copolymer architecture on self-assembly and phase separated nanostructures. Copolymers consisting of poly(hydroxyethyl acrylate)-x-(butyl acrylate) were prepared using photoiniferter polymerization to control functional group placement and molecular weight/polydispersity. Prepolymer configuration and concentration induced distinctly different effects on the resin flow and photopolymerization kinetics. The diblock copolymer self-assembled into nanostructured phases within the resin matrix, whereas the random copolymer formed an isotropic mixture. Rapid photopolymerization and ambient temperature conditions during cure facilitated retention of the self-assembled phases, leading to considerably different composite morphology and thermomechanical behavior. Increased loading of the diblock copolymer induced long-range ordered cocontinuous structures. Even with nearly identical prepolymer composition, controlled nanophase separation resulted in significantly enhanced tensile properties relative to those of the isotropic system. This work demonstrates that controlling phase separation with a block copolymer architecture allows access to nanostructured photopolymers with unique and enhanced properties.

Poly(N‐isopropylacrylamide) and Its Copolymers: A Review on Recent Advances in the Areas of Sensing and Biosensing

AbstractStimuli‐responsive polymers have received increasing attention for various applications due to their ability to adapt physical and chemical properties in response to external environmental stimuli. In this regard, poly(N‐isopropylacrylamide) (PNIPAM) is the most extensively studied stimuli‐responsive polymer and, consequently has been prominently featured in (bio)‐sensor development, adaptive coating technology, drug delivery, wound healing, tissue regeneration, artificial actuator design, sensor technology, responsive coatings, and soft robotics. This success can be mainly attributed to the accessible and versatile nature of the PNIPAM platform, thus allowing the synthesis of a wide variety of copolymer architectures, topologies and compositions. Within this review, the structural and compositional features of PNIPAM‐based materials in sensor and biosensor applications are discussed with a focus on the literature from 2016 until now. The reader is provided with the current state of the art regarding PNIPAM‐based sensor development and their molecular design. Finally, the challenges ahead in the successful implementation of PNIPAM‐based sensors are highlighted, as well as the opportunities in the rational design of improved PNIPAM‐based sensors. Altogether, this review provides comprehensive insights into the exciting and rapidly expanding field of PNIPAM‐based sensing systems, which will benefit the chemical, pharmaceutical, textile, and biotech industries is believed.

Local Confinement Effects of Block Copolymers Driving Self-Assembly of Nanoparticles into Discrete Pancake-Shaped Superlattices.

The utilization of polymer conformations to construct a variety of superlattices is a common method within the field. However, this technique often results in only long-range ordering rather than the formation of distinct superlattices. In this study, a well-organized array of discrete pancake-shaped superlattices (DPSs) is successfully obtained through the utilization of air-liquid interface self-assembly, facilitated by the confined environment created by a block copolymer. It is crucial to note that both the self-assembly behavior and resulting morphologies of the DPSs can be precisely tuned by adjusting several experimental parameters, most notably the concentration and molecular architecture of the block copolymers. Furthermore, this work provides valuable insights into the formation processes and mechanisms underpinning the DPSs. The approach described here is both straightforward and efficacious, establishing a strong foundation for subsequent research and the development of non-close-packed superlattice structures.

Impact of Copolymer Architecture on Demicellization and Cargo Release via Head-to-Tail Depolymerization of Hydrophobic Blocks or Branches.

Utilizing molecular dynamics simulations, we explored the demicellization and cargo release dynamics of linear and miktoarm copolymers, featuring one, two, and three hydrophobic blocks or branches, each capable of head-to-tail depolymerization. Our findings revealed that, under stoichiometric trigger molecule concentrations, miktoarms with three branches exhibited consistently faster depolymerization rates than those with two branches and linear copolymers. Conversely, at constant trigger molecule concentrations, the depolymerization rates of copolymers exhibited more complex behaviors influenced by two opposing factors: the excess of trigger molecules, which increased with a decrease in the number of hydrophobic branches or blocks, and simultaneous head-to-tail depolymerization, which intensified with an increasing number of branches. Our study elucidates the intricate interplay between copolymer architecture, trigger molecule concentrations, and depolymerization dynamics, providing valuable insights for the rational design of amphiphilic copolymers with tunable demicellization and cargo release properties.

Neutral Block Copolymer Assisted Gene Delivery using Hydrodynamic Limb Vein Injection.

Three different amphiphilic block copolymer families are synthesized to investigate new opportunities to enhance gene delivery via Hydrodynamic Limb Vein (HLV) injections. First a polyoxazoline-based family containing mostly one poly(2-methyl-2-oxazoline) (PMeOx) block and a second block POx with an ethyl (EtOx), isopropyl (iPrOx) or phenyl substituent (PhOx) is synthesized. Then an ABC poly(2-ethyl-2-oxazoline)-b-poly(2-n-propyl-2-oxazoline)-b-poly(2-methyl-2-oxazoline) triblock copolymer is synthesized, with a thermosensitive middle block. Finally, polyglycidol-b-polybutylenoxide-b-polyglycidol copolymers with various molar masses and amphiphilic balance are produced. The simple architecture of neutral amphiphilic triblock copolymer is not sufficient to obtain enhanced in vivo gene transfection. Double or triple amphiphilic neutral block copolymers are improving the in vivo transfection performances through HLV administration as far as a block having an lower critical solution temperature is incorporated in the vector. The molar mass of the copolymer does not seem to affect the vector performances in a significant manner.

Controlled architecture of multi-defense anti-fouling forward osmosis membrane for efficient shale gas wastewater treatment

Forward osmosis (FO) membrane process facilitates effective treatment of shale gas wastewater (SGW) due to its tolerance to high salinity and exceptional separation performance. However, serious membrane fouling remains a challenge regarding the complexity of realistic SGW. To address the fouling issues, controlled block copolymer architecture was constructed on the FO membrane surface to achieve combined effect of oil-resistance, self-regenerating, and fouling mitigation. In the modification process, zwitterionic polymer with strong hydrophilicity and fluoropolymers with low surface energy were successively grafted to the membrane active layer by atom transfer radical polymerization. The outermost fluoropolymer layer with low surface energy imparts the membrane with anti-oil and self-regenerating capabilities. Meanwhile, the strong hydration effect of the zwitterionic polymer ensures that nonspecific foulants breaking through the outermost defense are kept away from the membrane surface. According to the Extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) theory, the modified FO membrane exhibited a significantly higher total interaction energy (ΔGTOT) compared to the pristine membrane when exposed to various types of model foulants (bovine serum albumin, humic acid, sodium alginate, mineral oil). Furthermore, the advantage of having multiple defense mechanisms was further substantiated through dynamic filtration tests with realistic SGW. In comparison to the pristine TFC membrane, the modified membrane not only experienced a much smaller decrease in water flux (reduced by 52%) during fouling but also an exceptional flux recovery after cleaning (∼97%). These findings underscore that the modified FO membranes greatly mitigated membrane fouling associated with SGW through the synergistic interplay between a zwitterionic polymer and a low surface energy material, highlighting its promising potential in SGW treatment via membrane technology.

Self-Assembly of Rod-Coil Bottlebrush Copolymers into Degradable Nanodiscs with a UV-Triggered Self-Immolation Process.

Polymer nanodiscs, especially with stimuli-responsive features, represent an unexplored frontier in the nanomaterial landscape. Such 2D nanomaterials are considered highly promising for advanced biomedicine applications. Herein, we designed a rod-coil copolymer architecture based on an amphiphilic, tadpole-like bottlebrush copolymer, which can directly self-assemble into core-shell nanodiscs in an aqueous environment. As the bottlebrush side chains are made of amorphous, UV-responsive poly(ethyl glyoxylate) (PEtG) chains, they can undergo rapid end-to-end self-immolation upon light irradiation. This triggered nanodisc disassembly can be used to boost small molecule release from the nanodisc core, which is further aided by a morphological change from discs to spheres.

Self‐Assembly of Rod‐Coil Bottlebrush Copolymers into Degradable Nanodiscs with a UV‐Triggered Self‐Immolation Process

AbstractPolymer nanodiscs, especially with stimuli‐responsive features, represent an unexplored frontier in the nanomaterial landscape. Such 2D nanomaterials are considered highly promising for advanced biomedicine applications. Herein, we designed a rod‐coil copolymer architecture based on an amphiphilic, tadpole‐like bottlebrush copolymer, which can directly self‐assemble into core–shell nanodiscs in an aqueous environment. As the bottlebrush side chains are made of amorphous, UV‐responsive poly(ethyl glyoxylate) (PEtG) chains, they can undergo rapid end‐to‐end self‐immolation upon light irradiation. This triggered nanodisc disassembly can be used to boost small molecule release from the nanodisc core, which is further aided by a morphological change from discs to spheres.

Polymeric surfactants at liquid–liquid interfaces: Dependence of structural and thermodynamic properties on copolymer architecture

Polymeric surfactants are amphiphilic molecules with two or more different types of monomers. If one type of monomer interacts favorably with a liquid, and another type of monomer interacts favorably with another, immiscible liquid, then polymeric surfactants adsorb at the interface between the two liquids and reduce the interfacial tension. The effects of polymer architecture on the structural and thermodynamic properties of the liquid–liquid interface are studied using molecular simulations. The interface is modeled with a non-additive binary Lennard-Jones fluid in the two-phase region of the phase diagram. Block and gradient copolymer surfactants are represented with coarse-grained, bead-spring models, where each component of the polymer favors one or the other liquid. Gradient copolymers have a greater concentration at the interface than do block copolymers because the gradient copolymers adopt conformations partially aligned with the interface. The interfacial tension is determined as a function of the surface excess of polymeric surfactant. Gradient copolymers are more potent surfactants than block copolymers because the gradient copolymers cross the dividing surface multiple times, effectively acting as multiple individual surfactants. For a given surface excess, the interfacial tension decreases monotonically when changing from a block to a gradient architecture. The coarse-grained simulations are complemented by all-atom simulations of acrylic-acid/styrene copolymers at the chloroform-water interface, which have been studied in experiments. The agreement between the simulations (both coarse-grained and atomistic) and experiments is shown to be excellent, and the molecular-scale structures identified in the simulations help explain the variation of surfactancy with copolymer architecture.

Enhanced performance of phototransistor memory by optimizing the block copolymer architectures comprising Polyfluorenes and hydrogen-bonded insulating coils

Photonic transistor memory, which adopts the structure of a field-effect transistor, combines optical and electronic principles. Conjugated block copolymers (BCPs) are promising electret materials for optoelectronic applications. In this study, a series of BCPs comprising poly[2,7-(9,9-dioctylfluorene)] (PFO: A block) and poly(n-butyl acrylate-random-2-ureido-4[1H]pyrimidinone acrylate) (nBA-r-UPyA: B block), with linear-diblock (AB), branched (AB2), and linear-triblock (BAB) architectures, are synthesized to investigate hydrogen bonding effect stemming from UPyA groups. After thermal annealing, the soft segments of BCPs lead to self-assembled arrangements and smoother morphologies, providing an excellent interface for the deposition of the semiconducting channel layer. Furthermore, forming vertical phase-separated structures through thermal annealing significantly enhances the electron-capture capability. Subsequently, the BCP materials are applied in photonic transistor memory and conducted with electrical characterization. Our study reveals that different compositions of BCP architectures have a corresponding impact on the performance of photonic transistor memory devices. Consequently, AB of PFO-b-P(nBA-r-UPyA)s with a linear-diblock architecture presents an outperforming memory ratio of ∼105, outstanding memory stability over 104 s, and durability to consecutive write/erase processes.