Linear Brush Research Articles

Grafting chromatographic monoliths with charged linear polymers for highly productive and selective protein or plasmid DNA purification

Increased requirements for plasmid DNA (pDNA) in gene therapy and vaccination efforts bring the need for efficient large-scale production processes with high purity and productivity. Chromatographic purification of pDNA is often a bottleneck due to low dynamic binding capacities (DBC), pDNA recovery and/or low selectivity of columns. Ion exchangers (IEX) with charged groups on surface extenders (polyions formed by a grafting reaction and subsequents modification) have attracted attention due to their greatly enhanced productivity compared with traditional IEX. The ultimate goal of our investigation was to increase the DBC for pDNA on a monolith stationary phase by grafting the surface with linear polymethacrylate brushes (grafted chains), while retaining high pDNA recovery and chromatographic selectivity between pDNA and RNA impurities. The inner walls of the Convective Interaction Media® monolith channels were successfully coated with polyglycidyl methacrylate linear chains of varying densities and lengths by employing a controlled radical polymerization reaction. Glycidyl groups throughout the length of the formed grafted chains were converted to cation- (CEX) or anion-exchanging (AEX) moieties. Preliminary chromatographic evaluation of novel grafted CEX columns for different model proteins exhibited 10-times higher DBC with high elution recovery (99 %). Similar DBC improvement was proven for 7.3 kilobase pair pDNA, where the DBC10 increased from 1.8 mg pDNA per mL of non-grafted chromatographic support up to 15.2 mg per the most densely distributed and the longest grafted chains, modified with weak AEX groups. However, the DBC increase was partially at the expense of pDNA elution recovery, which presumably decreased due to entanglement of pDNA molecules inside the dense grafted layer. To confirm the hypothesis, we have prepared a series of columns differing in length and density of grafted chains and tested them for pDNA capture. A satisfactory compromise between high pDNA DBC and elution recovery was found with relatively long and low density grafted chains. The optimal grafted AEX column with 1 mL bed volume was evaluated for pDNA capture from neutralized E. coli lysate. With a capacity of 13.5 mg pDNA per mL support, ≥95 % elution recovery, and complete RNA clearance, the pDNA was successfully purified at loading flow rate of at least 15 column volumes per min. According to our knowledge and literature search, these process characteristics would enable one of the highest pDNA isolation productivities to be achieved with currently tested IEX.

Transparent PDMS Surfaces with Covalently Attached Lubricants for Enhanced Anti-adhesion Performance.

Liquid-like surfaces featuring slippery, omniphobic, covalently attached liquids (SOCALs) reduce unwanted adhesion by providing a molecularly smooth and slippery surface arising from the high mobility of the liquid chains. Such SOCALs are commonly prepared on hard substrates, such as glass, wafers, or metal oxides, despite the importance of nonpolar elastomeric substrates, such as polydimethylsiloxane (PDMS) in anti-fouling or nonstick applications. Compared to polar elastomers, hydrophobic PDMS elastomer activation and covalent functionalization are significantly more challenging, as PDMS tends to display fast hydrophobic recovery upon activation as well as superficial cracking. Through the extraction of excess PDMS oligomers and fine-tuning of plasma activation parameters, homogeneously functionalized PDMS with fluorinated polysiloxane brushes could be obtained while at the same time reducing crack formation. Polymer brush mobility was increased through the addition of a smaller molecular silane linker to exhibit enhanced dewetting properties and reduced substrate swelling compared to functionalizations featuring hydrocarbon functionalities. Linear polymer brushes were verified by thermogravimetric analysis. The optical properties of PDMS remained unaffected by the activation in high-frequency plasma but were impacted by low-frequency plasma. Drastic decreases in solid adhesion of not just complex contaminants but even ice could be shown in horizontal push tests, demonstrating the potential of SOCAL-functionalized PDMS surfaces for improved nonstick applications.

A review of stimuli-responsive polymer-based gating membranes.

The formation and properties of smart (stimuli-responsive) membranes are reviewed, with a special focus on temperature and pH triggering of gating to water, ions, polymers, nanoparticles, or other molecules of interest. The review is organized in two parts, starting with all-smart membranes based on intrinsically smart materials, in particular of the poly(N-isopropylacrylamide) family and similar polymers. The key steps of membrane fabrication are discussed, namely the deposition into thin films, functionalization of pores, and the secondary crosslinking of pre-existing microgel particles into membranes. The latter may be free-standing and do not necessitate the presence of a porous support layer. The temperature-dependent swelling properties of polymers provide a means of controlling the size of pores, and thus size-sensitive gating. Throughout the review, we highlight "positive" (gates open) or "negative" (closed) gating effects with respect to increasing temperature. In the second part, the functionalization of porous organic or inorganic membranes of various origins by either microgel particles or linear polymer brushes is discussed. In this case, the key steps are the adsorption or grafting mechanisms. Finally, whenever provided by the authors, the suitability of smart gating membranes for specific applications is highlighted.

Linear, Y- and Ψ-shaped poly(2-(dimethylamino)ethyl methacrylate) and poly(methyl methacrylate) brushes prepared by surface-initiated polymerization from a homologous series of ATRP initiators

A series of 3 homologous surface-anchored initiators for atom transfer radical polymerization has been used to graft linear, Y- and Ψ-shaped poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) and poly(methyl methacrylate) (PMMA) brushes from silicon surfaces. The film thicknesses of these architecturally different polymer brushes could be tuned both by controlling the polymerization time, as well as (as was shown for the polymerization of 2-(dimethylamino)ethyl methacrylate) by changing the monomer concentration. The library of linear, Y- and Ψ-shaped PDMAEMA and PMMA brushes was used to investigate the possible impact of polymer architecture on the swelling properties as well as the degrafting behavior of these surface-grown polymer films. The swelling of the PDMAEMA and PMMA brushes in PBS, respectively, acetone as a solvent was studied by ellipsometry. These experiments revealed a smaller swelling ratio for Y-shaped polymer brushes, as compared to linear analogues of comparable dry film thickness. Degrafting experiments were conducted with linear, Y- and Ψ-shaped PDMAEMA brushes in PBS. These experiments revealed a 2-fold, respectively, 3-fold increase in the initial rate constant of degrafting for the Y- and Ψ-shaped PDMAEMA brushes as compared to the linear analogues.

Morphological structure of variety populations of Clarkia unguiculata Lindl. in the south of Western Siberia

Clarkia unguiculata Lindl. - ornamental-flowering, annual, Californian crop - promising for landscaping in the south of Western Siberia. Decorativeness is determined by its morphobiological traits and adaptive properties. The aim of the work was to evaluate stratification variability of morphological structure of C. unguiculata Lindl. shoots in cultivated populations to improve the methodology of its breeding and seed production in the south of Western Siberia. Cultivated varieties Clarkia different producers were evaluated: C. unguiculata ‘Coral Reefs’ (Novosibirsk State Agricultural University), C. unguiculata ‘Albina’ and ‘Purpurnaya’ (LLC “Group of Companies “Gavrish”); C. unguiculata ‘Rubinovaya’ (Agrofirm Seeds of Altai LLC); C. unguiculata ‘Sakura’ (JSC “APK “ Russky Ogorod”). The study of biometric parameters and stratification variability of shoots was carried out on 10-20 test samples. In C. unguiculata plants 3 stratification of shoots were clearly distinguished: upper (main stem and the first two shoots of the second order), middle and lower (including seed shoots). A high correlation between peduncle productivity and linear brush size was found (r = 0.93). The total number of pedicels ranged from 32-50 per generative individual (CV = 20 %). The number of pedicels of the fourth (CV = 91,6 %) and fifth (CV = 64,2 %) orders was the most variable. The basiton type of branching was observed in the Cultivated varieties: C. unguiculata ‘Coral Reefs’, C. unguiculata ‘Sakura’ and C. unguiculata ‘Ruby’, while the acroton type was observed in the Cultivated varieties C. unguiculata ‘Albina’ and C. unguiculata ‘Purpurea’. Clustering of cultivated populations by the degree of development and productivity of flower stalks of different orders, by measuring Euclidean distances revealed 2 main clusters: the first included, characterized by high floral productivity original, variety Coral Reefs, registered 25.11.2022 in the State Variety Commission of the Russian Federation, and the second all the remaining cultivated populations: C. unguiculata ‘Rubinovaya’ with a minimum degree of flower productivity, C. unguiculata ‘Albina’ and C. unguiculata ‘Purpurnaya’ with average and C. unguiculata ‘Sakura’ above average. As a result, it was possible to identify important quantitative traits: the total number of peduncles per individual, linear size of the brush and the number of flowers on the peduncle. All cultivated populations are sources of a complex of breeding significant quantitative, morphobiological traits. The cultivated population of Clarkia unguiculata ‘Coral Reefs’ is recommended for landscaping the south of Western Siberia and other regions of Russia.

Antifouling Surfaces Based on Polyzwitterion Loop Brushes.

Antifouling surfaces have attracted increasing interest in recent years due to their potential application in various fields. In this work, we report a loop polyzwitterionic coating that exhibits excellent resistance to protein adsorption. Triblock and diblock copolymers of 2-[(2-hydroxyethyl)disulfanyl]ethyl methacrylate) (HSEMA) and 2-(dimethylamino)ethyl methacrylate) (DMAEMA) were synthesized by atom-transferred radical polymerization, followed by betainization of the DMAEMA block with 1,3-propane sultone and reduction of the disulfide bond in HSEMA to yield a triblock copolymer comprising a zwitterionic poly(sulfobetaine methacrylate) (PSBMA) midblock and poly(2-sulfanylethyl methacrylate) (PSEMA) terminal blocks as well as its diblock analogue that was of the same composition as the former and half the chain length. Both copolymers adsorbed to the gold substrate via the thiol groups in the terminal PSEMA block(s), creating loop and linear PSBMA brush coatings of comparable thickness, as revealed by X-ray photoelectron spectroscopy and ellipsometry. Adsorption of bovine serum albumin and fibrinogen as model proteins from solution to these surfaces was investigated by a quartz crystal microbalance with dissipation and confocal laser scanning microscopy (CLSM), and platelet and bacterial adhesions were assessed by scanning electron microscopy and CLSM. The results demonstrate that both linear and loop polyzwitterion brushes are excellent in resisting the adsorption of the foulants, and the loop brushes are superior to the linear analogues.

Topology Effects of Poly(2-ethyl-2-oxazoline) Brushes with Various Architectures for Antifouling Behavior under Shear Flow.

Polymer brushes with different topological architectures exhibit unparalleled interfacial and physicochemical properties and are being widely utilized in antifouling applications. However, there is an absence of a thorough understanding of the antifouling process of dynamic flow mediated by the topological structure of polymer brushes. Here, it is highlighted how the interface parameters related to biofouling in flowing carrier fluid are tuned by topologically different architectures. The mechanism by which three brushes with various topological structures (cyclic, looped, and linear brushes) encounter biological media was revealed by relating protein adhesion with nanomechanics and protein conformational transitions on poly(2-ethyl-2-oxazoline) (PEtOx) brushes. In contrast to the classically linear analogue, the cyclic PEtOx brushes confered an enhanced steric barrier and excellent lubrication at the critical density region. The impenetrable and smoother layer prevented the approach and shortened the residence time for protein on the surface, providing optimal antifouling properties at low shear rates. The looped brushes also significantly inhibited protein adhesion under prolonged high shear rates due to their unshakable conformational characteristics. These findings detailed a new evaluation framework behind polymer brushes of topology-driven biofouling repulsion under flow conditions and pointed the way toward a promising approach for the effectiveness of biomaterial design.

Abrasion resistance of spray coated anti-soiling coatings during waterless cleaning of PV modules

Dust deposition on photovoltaic (PV) modules leads to remarkably high energy loss, which has an enormous economic impact on PV plants. Anti-soiling coatings have been extensively studied as a cost-effective dust mitigation strategy in the PV market. However, such coatings applied to the top surface of the PV modules should be resilient to environmental stressors. Coated modules would also need periodic cleaning; thus, such anti-soiling coating must be abrasion-resistant. This article investigated the abrasion-resistant property of 4 types of commercial hydrophobic anti-soiling coatings. The study emulates the effects of different brush designs on the degradation of anti-soiling coatings under low soiling conditions. The samples were subjected to dry brush cleaning. We tested the samples with 3 different brush designs (linear brush 1, linear brush 2 and rotary brush) with a varying packing density of brush bristles. Linear brush 1 had 3.5 times higher packing density of brush bristles than linear brush 2 and rotary brush. By increasing the packing density of brush bristles by 3.5 times, the degradation rates were enhanced by factors varying from 1.2 X to 4.4 X in coated samples when cleaned with linear brush 1, compared to linear brush 2 and rotary brush. Phenylsilicone based coating shows higher degradation rates (varying from 2.9 X to 11.2 X) than fluoropolymer-based coatings. The result indicates a decline of the anti-soiling property as we see an increase in roll-off angle (compared to Mumbai, India’s tilt angle = 19º) with the increase in number of cycles. The results also show that compared to the structural brush design, the packing density of the brush bristle has a strong impact on the coating life. However, the actual coating life in the field would also be dependent on other environmental factors like the amount of dust deposit, moisture etc.

Topology-Directed Self-Locking of Colloidal Suprastructures

The robustness and stability of self-assembled colloidal suprastructures are pivotal and challenging in the field of soft condensed matter and nanotechnology. Herein, we develop a novel approach to “self-locking” the colloidal suprastructures to achieve excellent stability by taking advantage of the topology of polymer brushes on nanoparticles. Compared to linear polymer brushes, looped polymer brushes can significantly improve the structural stability of the suprastructures. A combination of experiments and simulations reveals that the suprastructures achieve their significant stabilities through a “self-locking” mechanism by forming folded entanglement between looped polymer molecules. The stabilized suprastructures can stay intact in various organic solvent environments or under heating and mechanical oscillations. Furthermore, the interparticle spacing of suprastructures can be modulated by controlling polymer conformations in an aqueous solution through varying salt concentrations. This new approach of “self-locking” provides an easy-to-operate strategy to stabilize suprastructures and modulate interparticle distances without adding chemicals, which allows the potentially wide applications of colloidal suprastructures under harsh environments.

The Topology of Polymer Brushes Determines Their Nanoscale Hydration.

Time-of-flight neutron reflectometry (ToF-NR) performed under different relative humidity conditions demonstrates that polymer brushes constituted by hydrophilic, cyclic macromolecules exhibit a more compact conformation with lower roughness as compared to linear brush analogues, due to the absence of dangling chain ends extending at the polymer-vapor interface. In addition, cyclic brushes feature a larger swelling ratio and an increased solvent uptake with respect to their linear counterparts as a consequence of the increased interchain steric repulsions. It is proposed that differences in swelling ratios between linear and cyclic brushes come from differences in osmotic pressure experienced by each brush topology. These differences stem from entropic constraints. The findings suggest that to correlate the equilibrium swelling ratios at different relative humidity for different topologies a new form of the Flory-like expression for equilibrium thicknesses of grafted brushes is needed.

Effect of branching in zwitterionic polymer brushes grafted from PES UF membrane surfaces via AGET-ATR(c)P

This research explored the relationship between the antifouling behavior of porous ultrafiltration (UF) membranes and linear or branched brushes adorning their surfaces. Polyethersulfone UF membranes were functionalized via one-pot lithiation/acylation to enable surface-initiated activators generated by electron transfer for atom transfer radical (co)polymerization of sulfobetaine methacrylate (SBMA) and N,N′-methylenebisacrylamide (MBAm). Changing the SBMA/MBAm ratio and polymerization time grafted brushes at different branching and thicknesses. Surface analyses verified differences in brush architecture and that the degree of grafting increased with grafting time – it was higher for linear brushes than branched ones. Colloidal probe lateral force atomic force microscopy (LFM) showed ideal hydration–lubrication propensity of the lower branching degree poly(SBMA-co-MBAm) over pristine, linear poly(SBMA), and higher branching poly(SBMA-co-MBAm)-grafted membranes. Sharp-tip LFM predicted a critical size of <15 nm for penetrating the branched brush layers. Fouling experiments with bovine serum albumin (∼10 nm) and dextran (∼18 nm) revealed that linear and branched modifications had significantly less fouling than the pristine membrane. An optimal degree of branching can limit foulant adsorption, but fouling could be enhanced if the polymers' hydration capacity was diminished relative to a less dense network. Fouling experiments with soluble microbial products further demonstrated the branched membrane's high antifouling activity.

Synthesis of hyperbranched polymer films via electrodeposition and oxygen-tolerant surface-initiated photoinduced polymerization

HypothesisHyperbranched polymers, not only possess higher functionality, but are also easier to prepare compared to dendrimers and dendric polymers. Combining electrodeposition and surface-initiated photoinduced electron transfer-reversible addition-fragmentation chain transfer (SI-PET-RAFT) polymerization is hypothesized to be a novel strategy for preparing hyperbranched polymer films on conductive surfaces without degassing. ExperimentsPolymer brush grafted films with four different architectures (i.e. linear, branched, linear-block-branched, and branched-block-linear) were prepared on gold-coated glass substrates using electrodeposition, followed by SI-PET-RAFT polymerization. The resulting film structure and thickness, surface topology, absorption property, and electrochemical behavior were confirmed by spectroscopy, microscopy, microbalance technique, and impedance measurement. FindingsThese hyperbranched polymer brushes were capable of forming a thicker but more uniformly covered films compared to linear polymer brush films, demonstrating that hyperbranched polymer films can be potentially useful for fabricating protective polymer coatings on various conductive surfaces.

Cationic bottlebrush brush polymers via sequential SI‐ROMP and SI‐ARGET‐ATRP

AbstractHere we describe a facile approach to preparing cationic bottlebrush brush polymers via sequential surface‐initiated (SI) ring‐opening metathesis polymerization and SI activators regenerated by electron transfer atom transfer radical polymerization. These techniques afforded both bottlebrush polymer brushes and their linear polymer brush analogues with cationic triphenylphosphonium pendant groups. Utilization of two controlled polymerization techniques with orthogonal requirements for monomers and additives allowed the polymerization of the backbone and the pendant side chains to be controlled independently. Grafting polymer side chains to a polymer brush backbone resulted in a thickness increase of ca 70%, indicating that the polymers are forced into a stretched conformation with greater surface coverage than was afforded by the linear brush polymers. As a result of the stretched conformation, greater ionic conductivity in the bottlebrush brush architectures was observed. © 2022 Society of Industrial Chemistry.

Shape Matters: Highly Selective Antimicrobial Bottle Brush Copolymers via a One-Pot RAFT Polymerization Approach.

The one-pot synthesis of antimicrobial bottle brush copolymers is presented. Reversible addition-fragmentation chain-transfer (RAFT) polymerization is used for the production of the polymeric backbone, as well as for the grafts, which were installed using a grafting-from approach. A combination of N-isopropyl acrylamide and a Boc-protected primary amine-containing acrylamide was used in different compositions. After deprotection, polymers featuring different charge densities were obtained in both linear and bottle brush topologies. Antimicrobial activity was tested against three clinically relevant bacterial strains, and growth inhibition was significantly increased for bottle brush copolymers. Blood compatibility investigations revealed strong hemagglutination for linear copolymers and pronounced hemolysis for bottle brush copolymers. However, one bottle brush copolymer with a 50% charge density revealed strong antibacterial activity and negligible in vitro blood toxicity (regarding hemolysis and hemagglutination tests) resulting in selectivity values as high as 320. Membrane models were used to probe the mechanism of shown polymers that was found to be based on membrane disruption. The trends from bioassays are accurately reflected in model systems indicating that differences in lipid composition might be responsible for selectivity. However, bottle brush copolymers were found to possess increased cytotoxicity against human embryonic kidney (HEK) cells compared with linear analogues. The introduced synthetic platform enables screening of further, previously inaccessible parameters associated with the bottle brush topology, paving the way to further improve their activity profiles.

Abrasion testing of anti-reflective coatings under various conditions

PV modules can quickly accumulate a light hindering layer of dust on the front glass, especially in arid regions. This soiling needs to be removed regularly, often using dry brushes as water is usually not easily available to wash the panels. Repeated cleaning negatively affects the anti-reflective coating (ARC) on the glass, leading to permanent transmittance loss and therefore a reduced energy yield. Within this work, two different ARCs and a reference glass are investigated regarding their resistance against harsh abrasion with a dry linear brushing abrasion cycle tester for laboratory and mobile use. The reduction of the spectral transmission is studied as a function of brushing cycles (0, 100, 1000) and integral relative transmittance loss has been calculated. Furthermore, a sensitivity analysis is performed for additional test parameters being type of dust, brush speed and weight. In particular, the type of dust shows a significant influence on the abrasion behavior. Less influential are the brush weight and the speed in the range used here. The dusts used in this setup were Feldspar, Calcite, Corundum and Arizona test dust in different particle size distributions. Using the hard Corundum dust, 1000 brush cycles lead to a relative loss in transmittance of about 3%. The application potential of the presented linear abrasion test for quality assessment and benchmarking of commercial glass coatings will be discussed. In particular, the implementation of region-specific test dusts in laboratory test procedures is of high interest for further standardization activities. • Linear brush abrasion test setup was used to test two different Anti-Reflective Coatings (ARCs). • Huge differences in transmittance loss between the coatings detected. • Investigation of the impact of test parameters brush speed, weight, brush cycles and type of dust. • Dust type and hardness are the most important influencing factors on the transmittance loss while brush speed and weight show no significant impact. • Method can be used for the development of site-specific ARC.

Linear and Ring Polymer Brushes: A Density Functional Theory Study

AbstractMonomer resolved density functional theory is employed to study structural properties and interactions between polymer‐grafted flat walls. Both linear and ring polymer brushes are considered. The three major control parameters are the grafting density, the grafted chain length, and temperature. The effect of these parameters on the brush–brush overlap and attractive interaction strength is analyzed. It is found that ring brushes provide better steric stabilization compared to their linear counterparts, in agreement with available experimental and simulation data.

Synthesis and micellar property of amphiphilic brush-arm star copolymers via living ROMP

Norbornene macromonomers (MMs) with polystyrene (PS) or poly(tert-butyl acrylate) (PtBA) side chains were synthesized by a combination of atom-transfer radical polymerization (ATRP) and click reactions. A series of amphiphilic linear and star-shaped brush block copolymers were obtained through sequential ring opening metathesis polymerization (ROMP) of MMs by the use of the highly active olefin metathesis Blechert's catalyst and tri-functionalized Blechert's catalyst respectively, followed by hydrolysis reaction. These well-defined diblock molecular brushes can undergo further self-assembly to form spherical micelles in solution, which have been characterized using DLS, AF4-MALLS, AFM, TEM and fluorescence spectra. The dynamic diameter increases as the hydrophilic backbone content increases for the vast majority of the linear and star copolymers. Brush-arm star diblock amphiphilic copolymers have smaller hydrodynamic diameter and aggregation number than the corresponding linear analogues. Moreover, the critical micelle concentration (CMC) values of star diblock copolymers show less sensitive to the variety of composition.

The collapse of polyelectrolyte brushes made of 4-arm stars mediated by trivalent salt counterions

ABSTRACT Langevin dynamics (LD) simulations were conducted to study the collapse of polyelectrolyte brushes made of 4-arm stars induced by trivalent salt counterions. Consistent with previous studies of the collapse of fully charged linear polymer brushes in the presence of trivalent salt counterions, the electrostatic bridging of grafted star chains by trivalent salt counterions plays a critical role in the bundle formation. In sharp contrast to the dominant probability of inter-chain bridging between a trivalent salt ion and multiple charged monomers from different chains in the collapse of polyelectrolyte brushes made of fully charged linear chains, the probability of intra-chain bridging was found to be much larger than that of inter-chain bridging for the collapse of fully charged star brushes due to the topological structure. The average number of bound charged monomers per trivalent salt counterion decreases drastically with decreasing charge fraction of grafted star chains. The ability of a trivalent salt counterion to bind with three or more charged monomers is greatly enhanced by increasing Bjerrum length. The probability of inter-chain bridging mode increases with increasing Bjerrum length. The larger Bjerrum length is, the smaller the bundle size and the tighter binding of the chains inside a bundle will become.

Tuning dispersity of linear polymers and polymeric brushes grown from nanoparticles by atom transfer radical polymerization

Molecular weight distribution imposes considerable influence on the properties of polymers, making it an important parameter, impacting morphology and structural behavior of polymeric materials.

Gold nanoparticles endowed with low-temperature colloidal stability by cyclic polyethylene glycol in ethanol

The colloidal stability of metal nanoparticles is tremendously dependent on the thermal behavior of polymer brushes. Neat polyethylene glycol (PEG) presents an unconventional upper critical solution temperature in ethanol, where phase segregation and crystallization coexist. This thermal behavior translated to a PEG brush has serious consequences on the colloidal stability in ethanol of gold nanoparticles (AuNPs) modified with PEG brushes upon cooling. We observed that AuNPs (13 nm diameter) stabilized with conventional linear PEG brushes (Mn = 6 and 11 kg mol-1) in ethanol suffer from reversible phase separation upon a temperature drop over the course of a few hours. However, the use of a polymer brush with cyclic topology as a stabilizer prevents sedimentation, ensuring the colloidal stability in ethanol at -25 °C for, at least, four months. We postulate that temperature-driven collapse of chain brushes promotes the interpenetration of linear chains, causing progressive AuNP sedimentation, a process that is unfavorable for cyclic polymer brushes whose topology prevents chain interpenetration. This study reinforces the notion about the importance of polymer topology on the colloidal stability of AuNPs.