Double‐hydrophilic block copolymer for encapsulation and two‐way pH change‐induced release of metalloporphyrins

A double hydrophilic block copolymer composed of poly(acrylic acid) (PAA) and poly(4‐vinyl pyridine) (P4VP) was obtained through hydrolysis of diblock copolymer of poly(tert‐butyl acrylate) (PtBA) and P4VP synthesized using atom transfer radical polymerization. Water‐soluble micelles with PAA core and P4VP corona were observed at low (acidic) pH, while micelles with P4VP core and PAA corona were formed at high (basic) pH. Two metalloporphyrins, zinc tetraphenylporphyrin (ZnTPP) and cobalt tetraphenylporphyrin (CoTPP), were used as model compounds to investigate the encapsulation of hydrophobic molecules by both types of micelles. UV–vis spectroscopic measurements indicate that micelles with P4VP core are able to entrap more ZnTPP and CoTPP as a result of the axial coordination between the transition metals and the pyridine groups. The study found that metalloporphyrins encapsulated by the micelles with PAA core could be released on pH increase, while those entrapped by the micelles with P4VP core could be released on pH decrease. This behavior originates from the two‐way pH change‐induced disruption of PAA‐b‐P4VP micelles. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 1734–1744, 2006     

In-situ investigation of the adsorption of globular model proteins on stimuli-responsive binary polyelectrolyte brushes

Binary brushes constituted from two incompatible polymers can be used in the form of ultrathin polymeric layers as a versatile tool for surface engineering to tune physicochemical surface characteristics such as wettability, surface charge, chemical composition, and morphology and furthermore to create responsive surface properties. Mixed brushes of oppositely charged weak polyelectrolytes represent a special case of responding surfaces that are sensitive to changes in the pH value of the aqueous environment and therefore represent interesting tools for biosurface engineering. The polyelectrolyte brushes used for this study were composed of two oppositely charged polyelelctrolytes poly(2-vinylpyridine) (P2VP) and poly(acrylic acid) (PAA). The in-situ properties and surface characteristics such as as surface charge, surface tension, and extent of swelling of these brush layers are functions of the pH value of the surrounding aqueous solution. To test the behavior of the mixed polylelctrolyte brushes in contact with biosystems, protein adsorption experiments with globular model proteins were performed at different pH values and salt concentrations (confinement of counterions) of the buffer solutions. The influence of the pH value, buffer salt concentration, and isoelectric points (IEP) of the brush and protein on the adsorbed amount and the interfacial tension during protein adsorption as well as the protein adsorption mechanism postulated in reference to recently developed theories of protein adsorption on polyelectrolyte brushes is discussed. In the salted regime, protein adsorption was found to be similar to the often-described adsorption at hydrophobic surfaces. However, in the osmotic regime the balance of electrostatic repulsion and a strong entropic driving force, "counterion release", was found to be the main influence on protein adsorption.     

Self‐assembled complexes of poly(acrylic acid) and poly(styrene)‐block‐poly(4‐vinyl pyridine)

Polymer complexes were prepared from high molecular weight poly(acrylic acid) (PAA) and poly(styrene)‐block‐poly(4‐vinyl pyridine) (PS‐b‐P4VP) in dimethyl formamide (DMF). The hydrogen bonding interactions, phase behavior, and morphology of the complexes were investigated using Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC), dynamic light scattering (DLS), atomic force microscopy (AFM), and transmission electron microscopy (TEM). In this A‐b‐B/C type block copolymer/homopolymer system, P4VP block of the block copolymer has strong intermolecular interaction with PAA which led to the formation of nanostructured micelles at various PAA concentrations. The pure PS‐b‐P4VP block copolymer showed a cylindrical rodlike morphology. Spherical micelles were observed in the complexes and the size of the micelles increased with increasing PAA concentration. The micelles are composed of hydrogen‐bonded PAA/P4VP core and non‐bonded PS corona. Finally, a model was proposed to explain the microphase morphology of complex based on the experimental results obtained. The selective swelling of the PS‐b‐P4VP block copolymer by PAA resulted in the formation of different micelles. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 1192–1202, 2009     

Neutral and Charged Brushes Covalently Grafted from OH-Functionalized Mica Surfaces using Surface-Initiated ATRP – Swelling Investigation by AFM

Poly(acrylic acid) (PAA) and poly(tert-butyl acrylate) (PBA) brushes of various grafting densities were prepared via surface-initiated polymerization of tert-butyl acrylate on mica. PAA was prepared by hydrolyzing the PBA brushes. The swelling behavior of PBA and PAA brushes was studied as a function of grafting density by AFM. The swelling of the polymer layer was found to be higher for PAA in water than for the PBA sample swollen with DFM.     

Hydrogen bonded layer-by-layer assembly of poly(2-vinylpyridine) and poly(acrylic acid): Influence of molecular weight on the formation of microporous film by post-base treatment

This article describes the buildup of hydrogen bonded multilayer film of poly(2-vinylpyridine) (P2VP) and poly(acrylic acid) (PAA), and the influence of polymer molecular weight on the formation of microporous film by post-base treatment. The formation of a microporous film involved a two-step mechanism: the release of PAA from P2VP/PAA multilayer, and the reorganization of the remaining P2VP on the substrate. Fourier transform infrared spectroscopy (FT-IR) indicated that the release of PAA from hydrogen bonded multilayer was a rapid process, which was almost independent of the molecular weight of PAA. Furthermore, the molecular weight of P2VP had a great effect on micropore formation by immersing the P2VP/PAA multilayer in basic solution. The rate of micropore formation increased with increasing molecular weight. We anticipate that a comparative study on P2VP/PAA films containing high or low molecular weight polymer provides a way to control the surface morphology, and will be helpful and constructive for the forthcoming discussion about the formation of the microporous film.     

Au/聚4-乙烯基吡啶-b-聚乙二醇嵌段聚合物刷的合成及其pH响应行为

作为受限高分子体系的一个经典模型,高分子刷在胶体稳定、聚合物链的自组装以及摩擦学等方面具有潜在的应用价值。 本文通过原子转移自由基聚合(ATRP)和点击化学(Click Chemistry)方法在金(Au)基底表面制备了pH响应性聚4-乙烯基吡啶-b-聚乙二醇(P4VP-b-PEG)嵌段聚合物刷。 通过频率-耗散型石英微天平(QCM-D)、X射线光电子能谱(XPS)和原子力显微镜(AFM)等技术手段分别对Au/P4VP-b-PEG聚合物刷经不同pH值溶液处理后的形态变化、表面组成和表面形貌进行了进一步深入研究。 结果表明,用不同pH值溶液处理P4VP-b-PEG嵌段聚合物刷后,该聚合物刷呈现刺激响应规律。 当pH=1.5时,P4VP链段质子化,由于静电排斥作用使P4VP-b-PEG链段呈伸展构象;当pH=11.5时,P4VP链段去质子化,并且由于失去部分结合水,P4VP-b-PEG链段呈塌缩构象。     

Adhesion between chemically heterogeneous switchable polymeric brushes and an elastomeric adhesive

We investigated the adhesive properties of binary heterogeneous polymer brushes made from end-functionalized polystyrene (PS) and poly(2-vinylpyridine) (P2VP) chains. The molecular organization of the mixed brush could be varied reversibly by exposure to selective solvents for PS (toluene) and for P2VP (acidic water). This exposure results in reversible switching of adhesive and wetting properties. The manner in which the adhesion switching occurs can be tuned by the composition of mixed brushes. However, the outer surface composition could be enriched more effectively in PS after the toluene treatment than in P2VP after the acidic water treatment. As a result, the mixed brush compositions that showed the largest difference in properties between an exposure to toluene and an exposure to water were the P2VP-rich compositions. Adhesive properties, tested against a soft hydrophobic pressure-sensitive adhesive (PSA) using a probe test, always showed smaller differences between solvent treatments than wetting properties with water, suggesting a much higher sensitivity of the hydrophobic/hydrophilic brushes to polar molecules than to nonpolar molecules.     

pH-Induced antireflection coatings derived from hydrogen-bonding-directed multilayer films

Hydrogen-bonding-directed layer-by-layer assembled films, based on polystyrene-block-poly(acrylic acid) (PS-b-PAA) block copolymer micelles and poly(4-vinylpyridine) (P4VP), were successfully fabricated in methanol. Varying the PAA content in the PS-b-PAA micelles afforded control over the film growth properties, especially the multilayer film thickness. Interestingly, antireflection films with refractive indices that could be tuned between 1.58 and 1.28 were obtained by treatment with an aqueous HCl solution (pH 2.27), and the transmittance obtained was as high as 98.4%. In acid solution, the pyridine group was protonated, destroying the hydrogen bonding between P4VP and PAA. A concomitant pH-induced polymer reorganization in the multilayers resulted in a porous honeycomb-like texture on the substrate.     

Peptide-modified inverted colloidal crystal scaffolds with bone marrow stromal cells in the treatment for spinal cord injury

Carboxyl groups of surface-tethered poly(acrylic acid) (PAA) brushes should be able to serve as versatile moieties for a wide range of chemical modifications, including an attachment of bioactive species that can act as sensing probes for biosensors. In this research, poly(tert-butyl acrylate) (Pt-BA) brushes were prepared by surface-initiated atom transfer radical polymerization of tert-butyl acrylate. PAA brushes were then obtained after removal of the tert-butyl groups from the Pt-BA brushes by acid hydrolysis. The carboxyl group density of the PAA brushes can be varied as a function of chain length or molecular weight. The reactivity of the carboxyl groups of PAA brushes towards the immobilization of biotin, a frequently used model bioactive probe in biosensing applications, was evaluated. Qualitative determination of streptavidin (SA) binding to the biotin-attached PAA brushes was verified by fluorescence microscopy. The efficiency of the PAA brushes to act as a three dimensional (3D) precursor layer for biosensing applications was further demonstrated using surface plasmon resonance (SPR), where the biotin-attached PAA brushes showed an enhanced signal for the biospecific binding of SA in comparison with a self-assembled monolayer (SAM) of a carboxyl-terminated alkanethiol, used as a model two-dimensional (2D) conventional precursor layer. The PAA brushes showed very low non-specific interactions with two other tested proteins of a similar pI but different sizes. This desirable feature should be highly beneficial for the development of biosensors.     

Transmission electron microscopy study of solvent-induced phase morphologies of environmentally responsive mixed homopolymer brushes on silica particles

We report in this work a transmission electron microscopy study of phase morphologies of environmentally responsive mixed poly( t-butyl acrylate) (P tBA)/polystyrene (PS) brushes and mixed poly(acrylic acid) (PAA)/PS brushes on 180 nm silica particles after treatments with nonselective good solvents and selective solvents, respectively. Mixed P tBA/PS brushes were grown from Y-initiator-functionalized silica particles by sequential atom transfer radical polymerization and nitroxide-mediated radical polymerization. Mixed PAA/PS brushes were prepared from mixed P tBA/PS brushes by removal of the t-butyl groups. For mixed P tBA/PS brushes with P tBA M n of 24.2 kDa and PS M n of 23.0 kDa and the corresponding mixed PAA/PS brushes, random worm-like, nearly bicontinuous nanostructures were formed from lateral microphase separation when the particles were cast from nonselective good solvents (chloroform for mixed P tBA/PS brushes and N, N-dimethylformamide for mixed PAA/PS brushes). The feature sizes were on the order of polymer chain root-mean-square end-to-end distances ( approximately 10 nm). In contrast, mixed P tBA/PS brushes with lower molecular weights (P tBA M n = 10.4 kDa and PS M n = 11.9 kDa) did not strongly phase separate after being cast from chloroform. After the solvents in the particle dispersions were gradually changed to selective solvents ( n-octane for mixed P tBA/PS brushes and H 2O for mixed PAA/PS brushes), isolated microdomains with an average size of 14-19 nm were formed as one grafted polymer collapsed and associated to form isolated microdomains, which were shielded by another grafted polymer yielding surface-tethered micellar structures. These results confirmed the theoretical predictions of the formation of "rippled" nanostructures and surface micellar structures of mixed homopolymer brushes induced by nonselective and selective solvents, respectively.     

Molecular‐level structures at poly(4‐vinyl pyridine)/acid interfaces probed by nonlinear vibrational spectroscopy

The molecular structures of the interfaces between a solid poly(4‐vinyl pyridine) (P4VP) surface and poly(acrylic acid) (PAA) as well as hydrochloric acid (HCl) solutions were probed using sum frequency generation (SFG) vibrational spectroscopy in situ in real time. Spectroscopic results clearly reveal that the PAA molecules are adsorbed onto the P4VP surface via hydrogen bonding at the P4VP/PAA solution interface while the P4VP surface is protonated at the P4VP/HCl solution interface. Consequently, the water molecules near the interfaces are strongly perturbed by these two interactions, exhibiting different orderings at the two interfaces. This work clearly demonstrates the power of studying the interfacial molecular‐level structures via nonlinear vibrational spectroscopy when molecular adsorption happens at the solid–liquid interface and paves a way for our future study on tracing the adsorption dynamics of polymer chains onto solid surfaces. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 848–852     

Friction and normal interaction forces between irreversibly attached weakly charged polymer brushes

Polyelectrolyte brushes were built on mica by anchoring polystyrene-poly(acrylic acid) (PS-b-PAA) diblock copolymers at a controlled surface density in a polystyrene monolayer covalently attached to OH-activated mica surfaces. Compared to physisorbed polymer brushes, these irreversibly attached charged brushes allow the polymer grafting density to remain constant upon changes in environmental conditions (e.g., pH, salt concentration, compression, and shear). The normal interaction and friction forces as a function of surface separation distance and at different concentrations of added salt (NaCl) were investigated using a surface forces apparatus. The interaction force profiles were completely reversible both on loading and receding and were purely repulsive. For a constant polymer grafting density, the influence of the polyelectrolyte charges and the Debye screening effect on the overall interaction forces was investigated. The experimental interaction force profiles agree very well with scaling models developed for neutral and charged polymer brushes. The variation of the friction force between two PAA brushes in motion with respect to each other as a function of surface separation distance appeared to be similar to that observed with neutral brushes. This similarity suggests that the increase in friction is associated with an increase in mutual interpenetration upon compression as observed with neutral polymers. The effect of the PAA charges and added ions was more significant on the repulsive normal forces than on the friction forces. The reversible characteristics of the normal force profiles and friction measurements confirmed the strong attachment of the PAA brushes to the mica substrate. High friction coefficients (ca 0.3) were measured at relatively high pressures (40 atm) with no surface damage or polymer removal.     

pH/Thermosensitive Hydrogels Formed at Low pH by a PMMA‐PAA‐P2VP‐PAA‐PMMA Pentablock Terpolymer

A poly(methyl methacrylate)‐block‐poly(acrylic acid)‐block‐poly(2‐vinyl pyridine)‐block‐poly(acrylic acid)‐block‐poly(methyl methacrylate) (PMMA‐PAA‐P2VP‐PAA‐PMMA), pentablock terpolymer has been synthesized by anionic polymerization with sequential addition of monomers and studied in aqueous media at low pH. The system exhibits combined properties and adopts the behavior of ‘telechelic’ polyelectrolytes and that of double hydrophilic polyampholytes. This complex behavior leads to the pentablock terpolymer forming a pH and temperature sensitive reversible hydrogel at very low polymer concentration.

     

Surface-grafted poly(acrylic acid) brushes as a precursor layer for biosensing applications: effect of graft density and swellability on the detection efficiency

Carboxyl groups along poly(acrylic acid) (PAA) brushes attached to the surface of a gold-coated substrate served as the precursor moieties for the covalent immobilization of amino-functionalized biotin or bovine serum albumin (BSA) to form a sensing probe for streptavidin (SA) or anti-BSA detection, respectively. Surface-grafted PAA brushes were obtained by acid hydrolysis of poly(tert-butyl acrylate) brushes, formerly prepared by surface-initiated atom transfer radical polymerization of tert-butyl acrylate. As determined by surface plasmon resonance, the PAA brushes immobilized with functionalized biotin or BSA probes not only showed good binding with the designated target analytes but also maintained a high resistance to nonspecific protein adsorption, especially those PAA brushes with a high surface graft density. Although the probe binding capacity can be raised as a function of the graft density of the PAA brushes or the amount of carboxyl groups along the PAA chains, the accessibility of the target analyte to the immobilized probe was limited at the high graft density of the PAA brushes. The effect was far more apparent for the BSA-anti-BSA probe-analyte pair than for the much smaller biotin-SA probe-analyte pair. The impact of the swellability of the PAA brushes, as tailored by the degree of carboxyl group activation, on both the sensing probe immobilization and analyte detection was also addressed. This investigation demonstrated that PAA brushes having a defined graft density have a promising potential as a precursor layer for biosensing applications.     

Formation of Core‐Shell‐Corona Micellar Complexes through Adsorption of Double Hydrophilic Diblock Copolymers into Core‐Shell Micelles

Summary: The complexation between polystyrene‐block‐poly(acrylic acid) (PS‐b‐PAA) micelles and poly(ethylene glycol)‐block‐poly(4‐vinyl pyridine) (PEG‐b‐P4VP) is studied, and a facile strategy is proposed to prepare core‐shell‐corona micellar complexes. Micellization of PS‐b‐PAA in ethanol forms spherical core‐shell micelles with PS block as core and PAA block as shell. When PEG‐b‐P4VP is added into the core‐shell micellar solution, the P4VP block is absorbed into the core‐shell micelles to form spherical core‐shell‐corona micellar complexes with the PS block as core, the combined PAA/P4VP blocks as shell and the PEG block as corona. A model is suggested to characterize the core‐shell‐corona micellar complexes.

Schematic formation of core‐shell‐corona (CSC) micellar complexes by adsorption of PEG‐b‐P4VP into core‐shell PS‐b‐PAA micelles.     

基于聚(2-甲基-2-噁唑啉)和聚丙烯酸的混合刷在毛细管电泳在线富集溶菌酶中的应用

制备了一种对溶菌酶具有可控吸附性能的混合刷涂层毛细管,用于毛细管电泳在线富集溶菌酶以提高其检测灵敏度。首先,分别通过阳离子开环聚合和可逆加成-断裂链转移（RAFT）聚合合成聚（2-甲基-2-噁唑啉）（PMOXA）和聚丙烯酸（PAA）,然后将甲基丙烯酸缩水甘油酯（GMA）分别与PMOXA和PAA通过自由基共聚和RAFT聚合合成出聚（2-甲基-2-噁唑啉）-r-甲基丙烯酸缩水甘油酯（PMOXA-r-GMA）和聚丙烯酸-b-聚甲基丙烯酸缩水甘油酯（PAA-b-PGMA）。将PMOXA-r-GMA和PAA-b-PGMA的混合溶液以一定比例加入到毛细管内,通过加热即可制备出基于PMOXA和PAA的混合刷涂层毛细管。X射线光电子能谱（XPS）对毛细管原材料的表面组成研究结果表明,当混合溶液质量浓度为20 g/L、PMOXA-r-GMA和PAA-b-PGMA质量比为1：1时,所得涂层中羧基的含量随着PAA链长的增加而增加;异硫氰酸荧光素标记溶菌酶（FITC-溶菌酶）吸附实验结果显示,通过改变环境的pH和离子强度（I）可以调控涂层毛细管对溶菌酶的吸附和释放,在pH 7（I=10^-5mol/L）条件下,毛细管可以吸附大量的溶菌酶,当条件变为pH 3（I=10^-1mol/L）时,吸附的溶菌酶可以被释放出来。将这种具有溶菌酶可控吸附性能的涂层毛细管用于毛细管电泳在线富集溶菌酶,当PAA链长是PMOXA链长的2.2倍时,溶菌酶的灵敏度增强因子为17.69,检出限为8.7×10^-5g/L;同一天内对溶菌酶连续测定5次以及连续测定5天,峰面积的日内、日间相对标准偏差（RSD）分别为2.9%和4.1%,迁移时间的日内、日间RSD分别为0.9%和2.1%。涂层的制备只需一步,简单易行,而且涂层具有很好的稳定性。本研究为毛细管电泳分析痕量蛋白质提供了一种简单有效的方法。     

Segregation of Coronal Chains in Micelles Formed by Supramolecular Interactions

Summary: Spherical micelles have been formed by mixing, in DMF, a poly(styrene)‐block‐poly(2‐vinylpyridine)‐block‐poly(ethylene oxide) (PS‐block‐P2VP‐block‐PEO) triblock copolymer with either poly(acrylic acid) (PAA) or a tapered triblock copolymer consisting of a PAA central block and PEO macromonomer‐based outer blocks. Noncovalent interactions between PAA and P2VP result in the micellar core while the outer corona contains both PS and PEO chains. Segregation of the coronal chains is observed when the tapered copolymer is used.

Inclusion of comb‐like chains with short PEO teeth in the corona triggers the nanophase segregation of PS and PEO as illustrated here (PS = polystyrene; PEO = poly(ethylene oxide)).     

The research on multi‐responsive azobenzene block copolymer and its self‐assembly behavior

The azobenzene‐based amphiphilic copolymers have drawn significant attention as a kind of multi‐responsive smart materials. The demand on deeper investigation of how the azobenzene group influences the micelles formation and light‐responsive behavior on molecular level is very urgent. In this article, multi‐responsive block copolymers, poly (acrylic acid)‐block‐poly[4'‐[[(2‐Methacryloyloxy)ethyl]ethylainino]azobenzene‐co‐poly (ethylene glycol) methyl ether methacrylate] (PAA‐b‐P (AzoMA‐co‐PEGMA)), with pH‐, light‐ and reduction‐responsiveness were synthesized by the monomers of AzoMA, PEGMA and acrylic acid via reversible addition‐fragmentation chain transfer polymerization (RAFT). The amphiphilic block copolymer presented aggregation‐induced emission effect, and it was pH, light, and reduction responsive. The results showed that the micelle size decreased with the decreasing of pH within a certain range. However, the particle size of micelles increased significantly when the pH was 4. Once adding reduction agent, the micelles were disassembly. Fluorescent molecule of Nile red was selected as a hydrophobic guest molecule to study the properties of encapsulating and releasing abilities of block copolymer micelles for guest molecules. The results showed that the loading capacity of three kinds of copolymer micelles was closely related to the aggregates formed by the hydrophobic block, mainly azobenzene block. Besides, the block copolymer micelles could release a certain amount of Nile red under the irradiation of UV light, the reduction with Na₂S₂O₄ as reductant, and the exposure to alkaline environment. The mechanism of how the different status of azobenzene group influenced the self‐assembly and multi‐responsive behavior was explored on molecular level.     

PVA/PAA thermo-crosslinking hydrogel fiber: preparation and pH-sensitive properties in electrolyte solution

The preparation of thermo-crosslinking hydrogel fibers composed of poly(vinyl alcohol) (PVA) and poly(acrylic acid) (PAA) was presented. The hydrogel fiber was prepared by extruding the spinning dope from in situ polymerization of acrylic acid in the presence of PVA into coagulating bath of saturated ammonium sulfate aqueous solution. The network was formed by thermally heating the dried fibers under vacuum. The final hydrogel fibers exhibit pH-sensitive behavior and show hysteresis loop in the pH range from 2.5 to 12.5. The pH value at which the swelling ratio of the fiber had a jump shifted to lower value with increasing the PAA content within the network. Increasing the heating temperature and time for the fibers, the swelling ratio decreased and the jump point pH shifted to higher pH value. The oscillatory swelling/contracting behavior of the hydrogel fiber exhibited a well reversible pH-responsive property.     

Complex pH- and temperature-sensitive swelling behavior of mixed polymer brushes

The ability of a mixed polymer brush consisting of poly(N-isopropyl acrylamide) (PNIPAAM) and poly(acrylic acid) (PAA) to modify physicochemical interfacial properties is presented. The answer of the binary brush toward changes of environmental conditions like temperature, salt concentration, and pH value was investigated by in situ spectroscopic VIS-ellipsometry as well as AFM and contact angle mesurements in the dry state and compared with the behavior of the corresponding homopolymer brushes. A coupled swelling of PNIPAAm and PAA could be found, leading to a complex pH-, salt-, and temperature-sensitive swelling behavior of these mixed brushes, also depending on the composition of the brush. The complex interaction of the two polymers resulted in new properties of the mixed system. Although the temperature sensitivity of the mixed system was decreased compared with that of the corresponding PNIPAAM brushes, the sensitivity toward pH and salt concentration was amplified compared with that of pure PAA brushes. Additionally it is shown that in spite of the decreased temperature sensitivity of the mixed brush, a temperature-dependent adsorption of human serum albumin was observed whereas an increased adsorption affinity was found that is not predictable from the adsorption affinity of the corresponding homopolymer brushes. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 1606–1615, 2010