Search Results (37)

Ultra-soft injectable hydrogels are paramount in biomedical applications such as tissue fillers, drug depots, and tissue regeneration scaffolds. Synthetic approaches relying on linear polymers are confronted by the necessity for significant dilution of polymer solutions to reduce chain entanglements. Bottlebrush polymers offer an alternative approach due to suppressed chain overlap and entanglements, which facilitates lower solution viscosities and increased gel softness. Leveraging the bottlebrush architecture in linear-bottlebrush-linear (LBL) block copolymer systems, where L is a thermosensitive linear poly(N-isopropylacrylamide) block, and B is a hydrophilic polyethylene glycol brush block, injectable hydrogels were designed to mimic tissues as soft as the extracellular matrix at high polymer concentrations. Compared to an analogous system with shorter brush side chains, increasing the side chain length enables a decrease in modulus by up to two orders of magnitude within 1–100 Pa at 20 wt% polymer concentrations, near to the physiological water content of ~70%. This system further exhibits thermal hysteresis, enabling stability with inherent body temperature fluctuations. The observed features are ascribed to kinetically hindered network formation by bulky macromolecules. Full article

In this review work, the different routes and methods for preparing hybrid materials based on nanostructured block copolymers (BCPs) and magnetic nanoparticles (MNPs) are analyzed, as they can be potentially employed in different sectors like biomedicine, electronic or optoelectronic devices, data storing devices, etc. The first procedure for their preparation consists of the nanostructuring of BCPs in the presence of previously synthesized NPs by modifying their surface for increasing compatibility with the matrix or employing magnetic fields for NP orientation, which can also promote the orientation of nanodomains. Surface modification with surfactants led to the selective confinement of NPs depending on the interaction (mainly hydrogen bonding) degree and their intensity. Surface modification with brushes can be performed by three methods, including grafting from, grafting to, or grafting through. Those methods are compared in terms of success for the positioning and confinement of NPs in the desired domains, showing the crucial importance of brush length and grafting density, as well as of NP amount and modification degree in the self-assembled morphology. Regarding the use of external magnetic fields, the importance of relative amounts of MNPs and BCPs employed and that of the magnetic field intensity for the orientation of the NPs and the nearby BCP domains is shown. The second procedure, consisting of the in situ synthesis of NPs inside the nanodomains by a reduction in the respective metallic ions or employing metal-containing BCPs for the generation of MNP patterns or arrays, is also shown. In all cases, the transference of magnetic properties to the nanocomposite was successful. Finally, a brief summary of some aspects about the use of BCPs for the synthesis, encapsulation, and release of MNPs is shown, as they present potential biomedical applications such as cancer treatment, among others. Full article

Amphiphilic block copolymers with complex topologies (e.g., star and brush topologies) have attracted significant attention in drug delivery owing to their superior performance over linear micelles. However, their precise synthesis and structure–property relationships require further investigation. In this study, hydroxylated polybutadiene with adjustable topology and hydroxyl group density was employed as a macroinitiator to synthesize well-defined amphiphilic poly (ethylene oxide)-b-poly(ε-caprolactone-ran-δ-valerolactone) (PEO-b-P(CL-ran-VL)) copolymers via ring-opening polymerization (ROP). A series of linear, star, linear–comb, and star–comb copolymers were prepared as curcumin-loaded micellar carriers for the study. The self-assembly behavior, drug encapsulation efficiency, and in vitro release profiles of these copolymers in aqueous environments were systematically investigated. The results demonstrated that increasing the branch length of star–comb copolymers effectively reduced micelle size from 143 to 96 nm and enhanced drug encapsulation efficiency from 27.3% to 39.8%. Notably, the star–comb architecture exhibited 1.2-fold higher curcumin encapsulation efficiency than the linear counterparts. Furthermore, the optimized star–comb nanoparticles displayed sustained release kinetics (73.38% release over 15 days), outperforming conventional linear micelles. This study establishes a quantitative structure–property relationship between copolymer topology and drug delivery performance, providing a molecular design platform for programmable nanocarriers tailored to diverse therapeutic requirements of various diseases. Full article

Brush-like graft copolymers (A-g-B), in which linear A-blocks are randomly grafted onto the backbone of a brush-like B-block, exhibit intense strain-stiffening and high mechanical strength on par with load-bearing biological tissues such as skin and blood vessels. To elucidate molecular mechanisms underlying this tissue-mimetic behavior, in situ synchrotron X-ray scattering was measured during uniaxial stretching of bottlebrush- and comb-like graft copolymers with varying densities of poly(dimethyl siloxane) and poly(isobutylene) side chains. In an undeformed state, these copolymers revealed a single interference peak corresponding to the average spacing between the domains of linear A-blocks arranged in a disordered, liquid-like configuration. Under uniaxial stretching, the emergence of a distinct four-spot pattern in the small-angle region indicated the development of long-range order within the material. According to the affine deformation of a cubic lattice, the four-spot pattern’s interference maxima correspond to 110 reflections upon stretching along the [111] axis of the body-centered unit cell. The experimental findings were corroborated by computer simulations of dissipative particle dynamics that confirmed the formation of a bcc domain structure. Full article

The role of interfacial effects on an ion-conducting poly(styrene-b-ethylene oxide) (PS-b-PEO or SEO) diblock copolymer doped with lithium bis(trifluoromethanesulfonyl) imide (LiTFSI) was investigated by electrochemical impedance spectroscopy (EIS). Coating the surface of commonly used stainless steel electrodes with a specific random copolymer brush increases the measured ionic conductivity by more than an order of magnitude compared to the uncoated electrodes. The increase in ionic conductivity is related to the interfacial structure of the block copolymer domain morphology on the electrode surface. We show that the impedance associated with the electrode–electrolyte interface can be detected using nonmetallic electrodes, allowing us to distinguish the ionic conductivity behaviors of the bulk electrolyte and the interfacial layers for both as-prepared and annealed samples. Full article

Nanopatterning methods utilizing block copolymer (BCP) self-assembly are attractive for semiconductor fabrication due to their molecular precision and high resolution. Grafted polymer brushes play a crucial role in providing a neutral surface conducive for the orientational control of BCPs. These brushes create a non-preferential substrate, allowing wetting of the distinct chemistries from each block of the BCP. This vertically aligns the BCP self-assembled lattice to create patterns that are useful for semiconductor nanofabrication. In this review, we aim to explore various methods used to tune the substrate and BCP interface toward a neutral template. This review takes a historical perspective on the polymer brush methods developed to achieve substrate neutrality. We divide the approaches into copolymer and blended homopolymer methods. Early attempts to obtain neutral substrates utilized end-grafted random copolymers that consisted of monomers from each block. This evolved into side-group-grafted chains, cross-linked mats, and block cooligomer brushes. Amidst the augmentation of the chain architecture, homopolymer blends were developed as a facile method where polymer chains with each chemistry were mixed and grafted onto the substrate. This was largely believed to be challenging due to the macrophase separation of the chemically incompatible chains. However, innovative methods such as sequential grafting and BCP compatibilizers were utilized to circumvent this problem. The advantages and challenges of each method are discussed in the context of neutrality and feasibility. Full article

The synthesis of polymer brushes on inorganic particles is an effective approach to surface modification. The polymer brushes on the surface endow the substrates with new surface properties. However, the lack of functional groups and the difficulty of surface modification have made it difficult to develop an effective method for the synthesis of polymer brushes on metal surfaces. Herein, a simple and versatile strategy for synthesizing polymer brushes on copper particles is reported. Tannic acid (TA) molecules are adsorbed onto the surfaces of copper particles, forming TA coatings. Quaternized poly(2-(dimethylamino)ethyl methacrylate)-block-polystyrene (qPDMAEMA-b-PS) block copolymer (BCP) chains are grafted on the TA coatings through hydrogen bonding and electrostatic interaction, and PS brushes are grafted on the copper particles. The effects of TA concentration on the adsorption of TA and PS brush synthesis are discussed. The PS brushes are able to form surface nanostructures on the copper particles through co-assembly with PDMAEMA-b-PS BCP chains. The effect of BCP concentration on the surface nanostructures is investigated. It is reasonable to expect that polymer brushes and surface nanostructures can be synthesized on different metal surfaces by using the TA-coating approach reported in this paper. Full article

Self-consistent field (SCF) theory serves as a robust tool for unraveling the intricate behavior exhibited by soft polymeric materials. However, the accuracy and efficiency of SCF calculations are crucially dependent on the numerical methods employed for system discretization and equation-solving. Here, we introduce a simple three dimensional SCF algorithm that uses real-space methods and adaptive discretization, offering improved accuracy and efficiency for simulating polymeric systems at surfaces. Our algorithm’s efficacy is demonstrated through simulations of two distinct polymeric systems, namely, block copolymer (BCP) films and polymer brushes. By enhancing spatial resolution in regions influenced by external forces and employing finer contour discretization at grafting chain ends, we achieve significantly more accurate results at very little additional cost, enabling the study of 3D polymeric systems that were previously computationally challenging. To facilitate the widespread use of the algorithm, we have made our 1D-3D SCF code publicly available. Full article

The effect of colloidal nanoparticles on the phase changes of the amphiphilic AB linear diblock, A₁A₂B, and A₂B heteroarm star copolymers confined between two polymer brush substrates was investigated by using a real-space self-consistent field theory. By changing the concentrations of nanoparticles and polymer brushes, the phase structure of the amphiphilic AB copolymer transforms from lamellar to core-shell hexagonal phase to cylinder phase. The pattern of A₂B heteroarm star copolymer changes from core-shell hexagonal phases to lamellar phases and the layer decreases when increasing the density of the polymer brushes. The results showed that the phase behavior of the system is strongly influenced by the polymer brush architecture and the colloidal nanoparticle numbers. The colloidal nanoparticles and the soft confined surface of polymer brushes make amphiphilic AB copolymers easier to form ordered structures. The dispersion of the nanoparticles was also investigated in detail. The soft surfaces of polymer brushes and the conformation of the block copolymers work together to force the nanoparticles to disperse evenly. It will give helpful guidance for making some new functional materials by nano etching technology, nano photoresist, and nanoprinting. Full article

Biofouling on surfaces, caused by the assimilation of proteins, peptides, lipids and microorganisms, leads to contamination, deterioration and failure of biomedical devices and causes implants rejection. To address these issues, various antifouling strategies have been extensively studied, including polyethylene glycol-based polymer brushes. Conducting polymers-based biointerfaces have emerged as advanced surfaces for interfacing biological tissues and organs with electronics. Antifouling of such biointerfaces is a challenge. In this study, we fabricated electrospun fibre mats from sulphonated polystyrene-block-poly(ethylene-ran-butylene)-block-polystyrene (sSEBS), infused with conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT) (sSEBS-PEDOT), to produce a conductive (2.06 ± 0.1 S/cm), highly porous, fibre mat that can be used as a biointerface in bioelectronic applications. To afford antifouling, here the poly(oligo (ethylene glycol) methyl ether methacrylate) (POEGMA) brushes were grafted onto the sSEBS-PEDOT conducting fibre mats via surface-initiated atom transfer radical polymerization technique (SI-ATRP). For that, a copolymer of EDOT and an EDOT derivative with SI-ATRP initiating sites, 3,4-ethylenedioxythiophene) methyl 2-bromopropanoate (EDOTBr), was firstly electropolymerized on the sSEBS-PEDOT fibre mat to provide sSEBS-PEDOT/P(EDOT-co-EDOTBr). The POEGMA brushes were grafted from the sSEBS-PEDOT/P(EDOT-co-EDOTBr) and the polymerization kinetics confirmed the successful growth of the brushes. Fibre mats with 10-mers and 30-mers POEGMA brushes were studied for antifouling using a BCA protein assay. The mats with 30-mers grafted brushes exhibited excellent antifouling efficiency, ~82% of proteins repelled, compared to the pristine sSEBS-PEDOT fibre mat. The grafted fibre mats exhibited cell viability >80%, comparable to the standard cell culture plate controls. Such conducting, porous biointerfaces with POEGMA grafted brushes are suitable for applications in various biomedical devices, including biosensors, liquid biopsy, wound healing substrates and drug delivery systems. Full article

In this research, a brush-like polyaniline (poly(2-acrylamide-2-methyl-1-propanesulfonate)-g-polyaniline)-b-poly(N-vinylcarbazole) (BL PAni) was developed as a strategy to overcome the limited processability and dedoping above pH 4 of conventional polyaniline (PAni). For the BL PAni synthesis, RAFT polymerization (homopolymer), RAFT-mediated surfactant-free emulsion polymerization (block copolymer), and interfacial oxidative polymerization were applied to graft the PAni chains. NMR and FT-IR spectroscopies were performed to confirm the structural elucidation of the reaction pathways, while the thermal properties were analyzed by TGA and DSC. Notably, the BL PAni presents absorption throughout the visible region and up to the near-infrared, showing dedoping resistance at up to 80 °C and at a neutral pH. The absorption range of the BL PAni, block copolymer, and homopolymer were studied by UV–Vis spectroscopy in solid-state and dispersion/solution, highlighting BL PAni and poly(anilinium 2-acrylamide-2-methyl-1-propanesulfonate)-b-poly(N-vinylcarbazole) (PAAMP-b-PVK) due to the π-stacking between the anilinium and carbazole groups. The cyclic voltammetry confirmed the persistence of electroactivity at a pH near 7. Full article

The ionization degree, charge density, and conformation of weak polyelectrolytes can be adjusted through adjusting the pH and ionic strength stimuli. Such polymers thus offer a range of reversible interactions, including electrostatic complexation, H-bonding, and hydrophobic interactions, which position weak polyelectrolytes as key nano-units for the design of dynamic systems with precise structures, compositions, and responses to stimuli. The purpose of this review article is to discuss recent examples of nanoarchitectonic systems and applications that use weak polyelectrolytes as smart components. Surface platforms (electrodeposited films, brushes), multilayers (coatings and capsules), processed polyelectrolyte complexes (gels and membranes), and pharmaceutical vectors from both synthetic or natural-type weak polyelectrolytes are discussed. Finally, the increasing significance of block copolymers with weak polyion blocks is discussed with respect to the design of nanovectors by micellization and film/membrane nanopatterning via phase separation. Full article

The order-disorder transitions (ODT) of core-shell bottle brush copolymer and its structural isomers were investigated by dissipative particle dynamics simulations and theoretically by random phase approximation. Introducing a chain topology parameter $\lambda$ which parametrizes linking points between M diblock chains each with N monomers, the degree of incompatibility at ODT (${\left(\chi N\right)}_{\mathrm{ODT}}$; $\chi$ being the Flory–Huggins interaction parameter between constituent monomers) was predicted as a function of chain topology parameter ($\lambda$) and the number of linked diblock chains per bottle brush copolymer (M). It was found that there exists an optimal chain topology about $\lambda$ at which ${\left(\chi N\right)}_{\mathrm{ODT}}$ gets a minimum while the domain spacing remains nearly unchanged. The prediction provides a theoretical guideline for designing an optimal copolymer architecture capable of forming sub-10 nm periodic structures even with non-high $\chi$ components. Full article

Bottlebrush copolymers with different chemical structures and compositions as well as diverse architectures represent an important kind of material for various applications, such as biomedical devices. To our knowledge, zwitterionic conjugated bottlebrush copolymers integrating fluorescence imaging and tumor microenvironment-specific responsiveness for efficient intracellular drug release have been rarely reported, likely because of the lack of an efficient synthetic approach. For this purpose, in this study, we reported the successful preparation of well-defined theranostic zwitterionic bottlebrush copolymers with unique brush-on-brush architecture. Specifically, the bottlebrush copolymers were composed of a fluorescent backbone of polyfluorene derivate (PFONPN) possessing the fluorescence resonance energy transfer with doxorubicin (DOX), primary brushes of poly(2-hydroxyethyl methacrylate) (PHEMA), and secondary graft brushes of an enzyme-degradable polytyrosine (PTyr) block as well as a zwitterionic poly(oligo (ethylene glycol) monomethyl ether methacrylate-co-sulfobetaine methacrylate) (P(OEGMA-co-SBMA)) chain with super hydrophilicity and highly antifouling ability via elegant integration of Suzuki coupling, NCA ROP and ATRP techniques. Notably, the resulting bottlebrush copolymer, PFONPN₉-g-(PHEMA₁₅-g-(PTyr₁₆-b-P(OEGMA₆-co-SBMA₆)₂)) (P₂) with a lower MW ratio of the hydrophobic side chains of PTyr and hydrophilic side chains of P(OEGMA-co-SBMA) could self-assemble into stabilized unimolecular micelles in an aqueous phase. The resulting unimolecular micelles showed a fluorescence quantum yield of 3.9% that is mainly affected by the pendant phenol groups of PTyr side chains and a drug-loading content (DLC) of approximately 15.4% and entrapment efficiency (EE) of 90.6% for DOX, higher than the other micelle analogs, because of the efficient supramolecular interactions of π–π stacking between the PTyr blocks and drug molecules, as well as the moderate hydrophilic chain length. The fluorescence of the PFONPN backbone enables fluorescence resonance energy transfer (FRET) with DOX and visualization of intracellular trafficking of the theranostic micelles. Most importantly, the drug-loaded micelles showed accelerated drug release in the presence of proteinase K because of the enzyme-triggered degradation of PTyr blocks and subsequent deshielding of P(OEGMA-co-SBMA) corona for micelle destruction. Taken together, we developed an efficient approach for the synthesis of enzyme-responsive theranostic zwitterionic conjugated bottlebrush copolymers with a brush-on-brush architecture, and the resulting theranostic micelles with high DLC and tumor microenvironment-specific responsiveness represent a novel nanoplatform for simultaneous cell image and drug delivery. Full article

In this paper, we described a straightforward one-step chemical method for the synthesis of semiconductor quantum dots(QDs)—block copolymer brushes functionalized graphene oxide(GO) fluorescence nanohybrids. The azobenzene-terminated block copolymer poly(N-isopropylacrylamid)-b-poly(styrene-co-5-(2-methacryoylethyloxymethyl)-8-quinolinol)(PNIPAM-b-P(St-co-MQ)) was modified on the surface of GO sheets via host–guest interactions between β-cyclodextrin-modified GO and azobenzene moieties, and simultaneously CdSe/ZnS QDs were integrated on the block copolymer brushes through the coordination between 8-hydroxyquinoline units in the polymer brushes and CdSe/ZnS QDs. The resulting fluorescence nanohybrid exhibited dual photoluminescence at 620 nm and 526 nm, respectively, upon excitation at 380 nm and LCST-type thermo-responsive behavior which originated from the change in the PNIPAM conformation in the block copolymer brushes of GO sheets. Full article