3,4-Dihydroxy-l-phenylalanine (l-DOPA) is considered to be responsible for the mussel adhesion to a variety of surfaces. A molecular level understanding of the interactions between DOPA molecules and surfaces with different wettability and chemistry, however, posts significant challenges to control marine antifouling. Here, different self-assembled monolayers (SAMs) on gold surfaces were fabricated: (i) OH-, (ii) COOH-, and (iii) CH3-terminations. The effect of surface wettability and chemistry on the adsorption of DOPA upon the series of surfaces was investigated in situ, showing that the adsorbed mass was lower and the water content of DOPA layer was higher on hydrophilic surfaces (including OH- and COOH-terminated SAMs) than that on hydrophobic ones (including CH3-terminated SAMs and gold surface). Direct evidence regarding the DOPA orientation and the interaction between DOPA and film surfaces were obtained: on the OH-terminated surface a flexible and loose structure formed via coordinate hydrogen bonds of the hydroxyl end groups of the surface interacting with carboxyl groups of DOPA, while for the CH3-terminated surface, DOPA molecules mainly adopt a flat conformation due to the formation of hydrophobic “bonds” between the hydrophobic functional groups of alkyl chains on surface and aromatic rings of DOPA molecules. This study led a new insight into the adsorption mechanisms based on the adsorption processes and layer structures, and it proposed novel concepts for the design of antifouling and adhesive surfaces.

An efficient method was developed to encapsulate water insoluble organic particles of Sudan red III (SR) in aqueous suspensions by using a polymerizable cationic gemini surfactant, 1,3-bis(N,N-dimethyl-N-cetylammonium)-2-(propylacrylate dibromide) (AGC16). The AGC16 coated SR microcapsules (AGC16@SR) were prepared by absorption of AGC16 on the surface of SR, followed by in situ homopolymerization (PAGC16). Several measurements, including transmission and scanning electron microscopy, isothermal titration calorimetry, zeta potential, electron paramagnetic resonance and small angle X-ray scattering, were performed to determine the adsorption amount of AGC16, and the layer structures and the molecular assembly mechanism in the AGC16@SR and PAGC16@SR systems, respectively. For comparison purposes, the polymerizable cationic surfactant with one head group and a single alkyl chain, acryloyloxyethyl-N,N-dimethyl-N-cetylammonium bromide (referred to as ASC16), as well as the systems of ASC16@SR and PASC16@SR were also investigated in parallel. It was found that AGC16 molecules and their aggregates were simultaneously assembled into a shell layer, in which the saturated adsorption amount of AGC16 on SR is less than 1/2 that of ASC16, but the assembly layer of AGC16 is more hydrophobic with greater packing tightness compared with that of ASC16. It was also revealed that after in situ homopolymerization, the microcapsule shell becomes more compact. In the case of PAGC16@SR, the layers show higher surface roughness and irregularity compared with that of PASC16@SR. Moreover, the sustained release behavior of SR was also evaluated. The results revealed that PAGC16@SR performed well for SR controlled release, which was sorted by release performance as the following sequence: PAGC16@SR > AGC16@SR > PASC16@SR > ASC16@SR. Thus, the polymerizable cationic gemini surfactant holds substantial potential to be developed as an ideal candidate of soft matter to construct efficient controllable release systems.

The adhesion of mussel foot proteins (Mfps) to a variety of surfaces has been widely investigated, but the mechanisms behind the mussel adhesion to surfaces with different properties are far from being understood. Most of Mfps contain a significant amount of 3,4-dihydroxyphenylalanine (DOPA) which is considered to be responsible for the strong wet adhesion. In the present work, self-assembled monolayers (SAMs) were prepared as a series of model surfaces with variable functional groups. DOPA-surface interactions were investigated using chemical force microscopy (CFM) for the first time, in which an atomic force microscope (AFM) tip was chemically modified with DOPA terminated groups. The ability of DOPA to adhere to different surfaces with variable wettability was compared, showing that DOPA behaves with the strongest and weakest adhesion to C6H5- and OH-terminated surfaces, respectively. The interaction strength of DOPA at different surfaces does not always increase with the increase of surface wettability, because the hydrophobic interaction does not play a decisive role in DOPA adhering to surfaces. By the use of classical and extended Derjaguin–Landau–Verwey–Overbeek (DLVO) theories, the contribution of non-DLVO forces was isolated. We found out DOPA can adhere to each surface functional group, since DOPA residues containing o-hydroxy or aromatic rings alone can control the adhesion process, and the aromatic ring is oriented perpendicularly or parallel to the surface. This study served as a basis for understanding the relationship between DOPA adhesion mechanisms and different wet surfaces, representing important concepts for the design of bioadhesive materials and anti-adhesion surfaces.

Mussel adhesion to a variety of surfaces has received considerable attention due to its ability to bind strongly to many surfaces under water. Understanding the interactions between mussel-derived adhesive proteins and surfaces with different chemical and physical properties is of great theoretical and practical interest. Here, we explored the adsorption behavior of mussel foot protein-1 (Mfp-1) onto self-assembled monolayers (SAMs) with varying wettability and chemistry, through quartz crystal microbalance with dissipation measurements, ellipsometry, X-ray photoelectron spectroscopy, and atomic force microscopy. The results showed significant differences in the structural conformations of protein adsorbed layers for the series of surfaces. Two mechanisms were found in all the systems; in the case of hydrophobic surfaces, the first regime corresponded to the initial adsorption of protein molecules onto the surfaces, and the second kinetic process was related to conformational changes, resulting in a relatively rigid and dense protein layer; while for hydrophilic surfaces, a loose and soft adsorbed protein film was generated. It was found that the adsorbed mass of Mfp-1 at the hydroxyl terminated SAM surface was the smallest among all the modified surfaces, because of the formation of hydration layers reducing protein adhesion effectively. Furthermore, the interaction mechanisms of protein molecules with solid surfaces were suggested, providing a new way of designing and developing underwater adhesive or anti-fouling materials.

The adsorption kinetics and equilibrium of amphiphilic dendrimers based on poly(amidoamine) modified with a dodecyl chain, GnQPAMC12 (n represents the generation number), with different generation numbers at a silica–water interface have been investigated. The effect of molecular shape with different charge characteristics on the adsorption kinetics, adsorption isotherms, and the conformation of a self-assembled layer has been elucidated. For the adsorption kinetics, two steps were observed including the adsorption of individual molecules at concentrations below the critical micelle concentration (cmc) and the predominant adsorption of aggregates above the cmc. However, the adsorption isotherm, as a function of the generation number, presented an exceptional characteristic, in which a decrease in adsorption mass with different levels occurred in a high generation of amphiphilic dendrimers, depending on the balance of hydrophobic interaction and electrostatic repulsion. Atomic force microscopy imaging showed that flattened films with pores (spacing) of various shapes and roughness of 3–4 nm were formed, of which the pores (spacing) decreased obviously as the generation number increased. The addition of electrolyte (NaBr) has a great effect on the film morphology formed by the G3QPAMC12 dendrimer adsorbed at the silica–water interface, showing that the film became closer with smaller pores with increased NaBr concentration.

The adsorption process of a geminized amphiphilic polyelectrolyte, comprising double elementary charges and double hydrophobic tails in each repeat unit (denoted as PAGC8), was investigated and characterized by means of quartz crystal microbalance with dissipation (QCM-D), ellipsometry, and atomic force microscopy (AFM). By comparison, the self-assembly behaviors of a traditional polyelectrolyte without hydrophobic chains (denoted as PASC1) and an amphiphilic polyelectrolyte with a single hydrophilic headgroup and hydrophobic tail in each repeat unit (denoted as PASC8) at the solid/liquid interface were also investigated in parallel. A two-regime buildup was found in both amphiphilic systems of PASC8 and PAGC8, where the first regime was dependent on electrostatic interactions between polyelectrolytes and oppositely charged substrates, and the rearrangements of the preadsorbed chains and their aggregation behaviors on surface dominated the second regime. Furthermore, it was found that the adsorbed amount and conformation changed as a function of the charge density and bulk concentrations of the polyelectrolytes. The comparison of the adsorbed mass obtained from QCM-D and ellipsometry allowed calculating the coupling water content which reached high values and indicated a flexible aggregate conformation in the presence of PAGC8, resulting in controlling the suspension stability even at an extremely low concentration. In order to provide an insight into the mechanism of the suspension stability of colloidal dispersions, we gave a further explanation with respect to the interactions between surfaces in the presence of the geminized polyelectrolyte.

The current study is aimed at investigating the effect of cationic charge density and hydrophobicity on the antibacterial and hemolytic activities. Two kinds of cationic surfmers, containing single or double hydrophobic tails (octyl chains or benzyl groups), and the corresponding homopolymers were synthesized. The antimicrobial activity of these candidate antibacterials was studied by microbial growth inhibition assays against Escherichia coli, and hemolysis activity was carried out using human red blood cells. It was interestingly found that the homopolymers were much more effective in antibacterial property than their corresponding monomers. Furthermore, the geminized homopolymers had significantly higher antibacterial activity than that of their counterparts but with single amphiphilic side chains in each repeated unit. Geminized homopolymers, with high positive charge density and moderate hydrophobicity (such as benzyl groups), combine both advantages of efficient antibacterial property and prominently high selectivity. To further explain the antibacterial performance of the novel polymer series, the molecular interaction mechanism is proposed according to experimental data which shows that these specimens are likely to kill microbes by disrupting bacterial membranes, leading them unlikely to induce resistance.

The self-aggregation of amphiphilic dendrimers G1QPAMCm based on poly(amidoamine) PAMAM possessing the same hydrophilic group but differing in alkyl chain length in aqueous solution was investigated. Differences in the chemical structures lead to significant specificities in the aggregate building process. A variety of physicochemical parameters presented monotonous regularity with the increase in alkyl chain length in multibranched structure, as traditional amphiphilic molecules. A significant difference, however, existed in the morphology and the microenvironment of the microdomain of the aggregates, with G1QPAMCm with an alkyl chain length of 16 intending to form vesicles. To obtain supporting information about the aggregation mechanism, the thermodynamic parameters of micellization, the free Gibbs energy ΔGmic, and the entropy ΔSmic were derived subsequently, of which the relationship between the hydrophobic chain length and the thermodynamic properties indicated that the self-assembly process was jointly driven by enthalpy and entropy. Other than traditional surfactants, the contribution of enthalpy has not increased identically to the increase in hydrophobic interactions, which depends on the ratio of the alkyl chain length to the radius in the headgroup. Continuous increases in the hydrophobic chain length from 12 to 16 lead to the intracohesion of the alkyl chain involved in the process of self-assembly, weakening the hydrophobic interactions, and the increase in −ΔHmic, which offers an explanation of the formation of vesicular structures.

A novel amphiphilic homopolymer (PAGC8), containing two hydrophilic head groups and double hydrophobic tails in each repeat unit, has been prepared by solution polymerization and named as “a geminized amphiphilic homopolymer” in this paper, which is capable of self-assembling into various nanoobjects depending on the solution concentration and solvent properties. Characterization of the self-assembly behaviors was carried out by steady-state fluorescence, transmission electron microscopy and nuclear magnetic resonance techniques. Particular emphasis was dedicated to the environmental responsiveness of the assemblies. The morphologies were observed to transform from micelle-type to vesicles on adding a certain amount of ethanol. It is noteworthy that the assemblies were able to trap hydrophilic (rhodamine B) and hydrophobic (Sudan Red) molecules. Subsequently different nanoobjects were found after the encapsulation. To probe the effect of the topological structure on the self-assembly behaviors, the properties of an additional homopolymer with single charge pendant architecture on the backbone were investigated for comparison. Significant differences in structure between the two architectures brought out remarkable variations in aggregates, which were non-responsive to the solvent environment, or encapsulation of molecules. Based on the experimental results, we proposed a possible mechanism of the morphological transitions of the assemblies.

•The adsorption behaviors of amphiphilic dendrimers with different alkyl chain lengths showed unique regularity.•The amphiphilic dendrimer possesses superior properties of breaking W/O crude oil emulsions.•The dilational viscoelasticity properties contribute to explaining the demulsification behaviors.The dynamic surface tension and dilational viscoelasticity properties of amphiphilic polyamidoamine (PAMAM) dendrimers were investigated to probe the hydrophobic chain effect on the interfacial properties and the demulsification behaviors. The values of dynamic parameters n and t* representing diffusion speed of the molecules obtained according to the Rosen equation decreased with the increasing of bulk concentration. Taking the hydrophobic effect into consideration, the t* values decreased and n values increased with the increase of alkyl chain length, suggesting easier adsorption and faster diffusion for longer hydrophobic chain which was opposite to the tendency of traditional surfactants. Further dilational viscoelasticity studies demonstrated that the properties referring to adsorption and exchange-diffusion were probably affected by the aggregates conformation at the interface. Subsequently, from the demulsification experiments a conclusion can be drawn that the amphiphilic dendrimers with branched dendritic structure possesses superior properties of breaking W/O crude oil emulsions, showing a certain correlation to the dilational viscoelasticity properties.

A novel amphiphilic polyelectrolyte denoted as PAGC8 and a traditional amphiphilic polyelectrolyte denoted as PASC8 were prepared. PAGC8 consisted of gemini-type surfactant segment based on 1,3-bis (N,N-dimethyl-N-octylammonium)-2-propyl acrylate dibromide, while PASC8 incorporated acryloyloxyethyl-N,N-dimethyl-N-dodecylammonium bromide as single chain surfactant units within its repeat unit structure. Turbidity, stability, and zeta potential measurements were performed in the presence of PAGC8 and PASC8, respectively, to evaluate their effectiveness in inducing solid/liquid separations. It was found that the maximum transmittance was observed before the zeta potential values reached the isoelectric point, implying that not only charge neutralization but also charge-patch mechanism contributed to the separation process. Colloid probe atomic force microscopy technique was introduced to directly determine the interactions between surfaces in the presence of ultrahighly charged amphiphilic polyelectrolyte. On the basis of the AFM results, we have successfully interpreted the influence of the charge density of the polyelectrolytes on the phase stability. Electrostatic interaction played the dominant role in the flocculation processes, although both electrostatic interaction and hydrophobic effect provided contributions to the colloidal dispersions. The attractions upon surfaces approach in the case of PAGC8 were significantly larger than that of PASC8 due to the higher charge density. The strong peeling events upon retraction in the presence of PAGC8 implied that the hydrophobic effect was stronger than that of PASC8, which displayed the loose pulling events. A strong attraction was identified at shorter separation distances for both systems. However, these interactions cannot be successfully described by the Derjaguin–Landau–Verwey–Overbeek (DLVO) theory of colloid stability due to the participation of charge-patch and strong hydrophobic effect. To account for the additional interactions, we proposed an extended DLVO empirical model to explain the non-DLVO forces in the systems. A reasonable physical model was also proposed to further describe the interactions between surfaces in the two amphiphilic polyelectrolyte systems.

In this work, a series of novel amphiphilic dendrimers taking polyamidoamine dendrimer as the core with different hydrophobic tails QPAMCm were synthesized and the dilational properties were studied as monolayers by dilational rheological measurements at the water–air and water–n-heptane interfaces to explore the nature of adsorption behaviors. The results showed that the maximum values of the dilational modulus seemed to have no obvious variation in a wide change of hydrophobic chain length at the surface. However, there was considerable variability in the tendency of the influence of bulk concentration on the dilational modulus at the two different interfaces. It was interestingly found that the diffusion-exchange process slowed down with the increase of alkyl chain length leading to more elastic nature of adsorption film, which was contrary to the tendencies of conventional single chain and gemini surfactants. It is reasonable to consider that, in the case of the molecule having short chain length such as QPAMC8, the alkyl chains are too short to overlap across the headgroup, enable the intermolecular hydrophobic interaction to be predominant with increasing of surface concentration, which enhances the elasticity and shows the slowest diffusion-exchange process. Whereas, when the chain length increases to 12 or 16, the alkyl chains are long enough to act intramolecularly to form intracohesion conformation, which results in enhancing the diffusion-exchange process. In conclusion, the interfacial behaviors are dictated by the size ratio between the tail and headgroup. A reasonable model with respect to the molecular interaction was proposed on the basis of experimental data. The results of interfacial tension relaxation and dynamic light scattering (DLS) experiments, in accord with the proposed mechanism, also present the unusual tendency comparing to the traditional single or gemini surfactants.

Properties of binary surfactant systems of nonionic surfactants poly(ethylene oxide) (PEO) lauryl ethers (C12E10, C12E23, C12E42) with a cationic gemini surfactant, butanediyl-α,ω-bis(tetradecyldimethylammonium bromide) (14-4-14), have been investigated by Steady-state Fluorescence (FL), zeta potential, Dynamic Light Scattering (DLS), Transmission Electron Microscopy (TEM), Cryogenic Transmission Electron Microscopy (CryoTEM), and X-ray Diffraction (XRD). Through FL measurements, critical micelle concentration (CMC) of the three binary systems for different mixing mole fractions is determined and the values fall between those of pure constituent surfactants. Ideal CMC (CMCideal), mole fraction in aggregates (X), interaction parameter (β), activity coefficients (f1 and f2), and excess free energy of mixing (ΔGex) have been calculated. All these parameters indicate nonideal behavior and synergistic interactions between the constituent surfactants, which is explained in terms of electrostatic attraction between headgroups of constituent surfactants and reduction of electrostatic repulsion between headgroups of 14-4-14 due to the presence of nonionic surfactants. DLS, TEM and CryoTEM results show that nonionic surfactants facilitate the formation of larger aggregates. Micelles and vesicles in larger size compared with those of 14-4-14 coexist in the mixed solutions. Both surfactant composition and PEO chain length are found to play a strong effect on the properties of the binary systems.Graphical abstractCryogenic Transmission Electron Microscopy image of micelles and vesicles formed by binary surfactant system of nonionic surfactant and cationic gemini surfactant.Research highlights► The aggregation properties of three binary surfactant systems were investigated. ► The presence of nonionic surfactants has an effect on CMC and aggregate morphology. ► There are strong synergistic interactions between the constituent surfactant. ► Surfactant composition and PEO chain length affect the aggregation properties. ► The work contributes to understand the aggregation behavior and the mixing effect.

A novel series of comb-like random copolymers were prepared by polymerization of amphiphilic macromonomers, 2-(acrylamido)-octane sulfonic acid (AMC8S), 2-(acrylamido)-dodecane sulfonic acid (AMC12S), and 2-(acrylamido)-hexadecane sulfonic acid (AMC16S), with 2-(acrylamido)-2-methylpropanesulfonic acid (AMPS) respectively. The synthesis of the polymers with the same contents of amphiphilic units as side chains, but different chain length, enabled us to study the chain length dependence of their association in salt solution. Steady-state fluorescence measurements with pyrene as a polarity probe, quasielastic light scattering techniques (QELS) and transmission electron micrograph (TEM) were employed to investigate the associative properties of the system. The above investigations showed that all kinds of side chains begin to assemble at certain polymer concentrations and the critical aggregation concentration (CAC) decrease dramatically with the increase in the length and content of alkyl. An interesting phenomenon is that the assembly tends more favorably to occur among different molecules rather than within single molecule when the number of carbon atoms in the alkyl groups or the polymer concentration increases, leading to the formation of larger multimolecular micelle-like aggregate. The aim of the present work is to establish the fundamental preconditions of intramolecular and intermolecular association fashions for the polymers, which is useful for the exploitation of functional groups and contributes to the development of amphiphilic random polymers.Increase the number of carbon atoms in the alkyl group or polymer concentration can lead the association of side chains to occur more preferentially among different molecules.

Aggregation behavior of an amphiphilic dendritic block copolymer, a generation 1.0 poly(amidoamine) (G1.0 PAMAM) dendrimer based poly(propylene oxide) (PPO)-block-poly(ethylene oxide) (PEO) copolymer that was abbreviated as PPP, with a cationic gemini surfactant butanediyl-α,ω-bis(tetradecyldimethylammonium bromide) (14-4-14) in aqueous solution was investigated by the measurements of steady-state fluorescence (FL), cloud point (CP), transmission electron microscope (TEM), and dynamic light scattering (DLS). Through FL method, the critical aggregation concentration (CAC) of PPP in the absence and presence of 14-4-14 was determined. As the concentration of 14-4-14 increases, CAC values increase, suggesting the participation of copolymer−surfactant complexes in aggregate formation. The CP temperature of PPP increases as the content of 14-4-14 increases in the mixed system, which indicates that 14-4-14 increases the solubility of PPP. From TEM and DLS, the morphology and size distribution of the aggregates were obtained. The spherical aggregates are found to be larger in size and narrower in distribution with the addition of 14-4-14, which confirms further the formation of mixed aggregates. All of the above are explained on the basis of strong interactions between PPP and 14-4-14. Through hydrophobic interactions, 14-4-14 molecules can associate with PPP molecules to form copolymer−surfactant complexes that can aggregate further.

A novel series of comb-like amphiphilic statistical copolymers were synthesized by polymerization of an amphiphilic macromonomer, 2-(acrylamido)-dodecanesulfonic acid (AMC12S), with 2-(acrylamido)-2-methylpropanesulfonic acid (AMPS). The association behaviors of the polymers in NaCl aqueous solution were investigated by steady-state fluorescence measurements with pyrene as a polarity probe, quasielastic light scattering techniques (QELS), and a transmission electron micrograph (TEM). It was found that the series of polymers shows a strong tendency for interpolymer association, leading to the formation of multimolecular aggregates. The critical aggregation concentration (CAC) and the micropolarity of the polymer aggregates strongly depend on AMC12S mole fraction (X). An interesting feature of the polymers is that hydrodynamic sizes of the aggregates (Rh) continuously decrease with increasing X, and the increase extent of Rh with increasing polymer concentration (C) inclines to be smaller for higher X, suggesting that the polymer aggregates become a closed type progressively with increasing X.

A novel class of amphiphilic cationic polyelectrolytes, poly(A-co-G)s, comprising of gemini type surfactant segment 1,3-bis(N,N-dimethyl-N-dodecylammonium)-2-propylacrylate dibromide (G) and acryloyloxyethyl trimethyl ammonium chloride (A), were synthesized. Their aggregation properties were investigated by employing fluorescence spectroscopy, dynamic light scattering, transmission electron microscopy, and ζ-potential measurements. For comparison, a series of polyelectrolytes containing a traditional single alkyl chain surfactant unit (acryloyloxyethyl-N,N-dimethyl-N-dodecylammonium bromide (D)), poly(A-co-D)s, were also synthesized and investigated. It was found that the critical aggregation concentration (cac) of poly(A-co-G)s is much lower than that of poly(A-co-D)s. The huge interpolymer aggregates (with a hydrodynamic radius of >450 nm) occur in poly(A-co-G)s aqueous solution, and the size of aggregates increases with the increase of the molar content of the gemini-type surfmer segment and the concentration of the copolymer. The size of aggregates in poly(A-co-D)s aqueous solution is much smaller than poly(A-co-G)s, which also increases with the increase of the molar content of the single alkyl chain surfmer segment and the concentration of the copolymer. The results of aggregation number and charge density of aggregate in poly(A-co-G)s and poly(A-co-D)s indicate that the copolymers have a strong tendency toward interpolymer aggregation and the aggregates in poly(A-co-G)s are much more compact than those of poly(A-co-D)s. These results are interpreted in terms of the synergistic effects of double hydrophobic chains on the gemini surfactant unit.

With 3.0 G polyamidoamine (PAMAM) as initiator and poly (propylene oxide) (PPO)–poly (ethylene oxide) (PEO) blocks as branches, a new class of amphiphilic copolymers were synthesized. The critical micelle concentration (CMC) and γCMC (surface tension at CMC) values were determined by surface tension measurement, and the result showed that they both decrease with the increase of amphiphilic branch length. The turbidity properties were investigated and it was found that the cloud point (CP) temperature decreases as the PEO block length increases. Freeze-fracture transmission electron microscopy (FF-TEM) results exhibited spherical shape of aggregates with the most probable distribution size of around 100 nm, which agrees with the results of the dynamic light scattering (DLS). Moreover, the relationship between PPO block length and the activity and CP properties was discussed.

We present the synthesis and the characterization of a new class of modified polyacrylamides (MPAM) with the unusual trait of strong emulsification ability, viscosity enhancement capacity, and significant salt tolerance. Besides, the synthesized polymers have the peculiar aggregation behaviors in aqueous solution. The synthesis was carried out by polymerizing the monomers such as acrylamide (AM), acrylic acid (AA), unsaturated amphiphilic functional moieties, and high steric hindrance functional units. Their aggregation behaviors were investigated by using a scanning electron microscope (SEM). The emulsion, formed by 10 ml of MPAM (with the polymer concentration of 1,000 mg/L) and the 10 ml of crude oil, was very stable, which indicates that the synthesized polymers have unique emulsification properties. The strong hydrophobic interaction between molecules and the three-dimensional network formed in aqueous solution were exhibited by the experimental results of steady fluorescence and SEM experiments. It could be concluded that the performance of polymers for enhanced oil recovery (EOR) can be remarkably enhanced by introducing functional monomers to polymer backbone, which allows the new class of modified polymers to have more promising application in enhanced oil recovery.

A series of nonionic dimeric poly(ethylene oxide) surfactants, HBA(EO)n (n = 9, 20, 80, respectively), were synthesized and characterized. The surface properties, such as the critical micelle concentration, CMC, minimum surface tension, γCMC, surface excess concentration, Γcmc, and surface area per molecule, Amin, have been determined by means of surface tension measurements. Effects of salt and pH on the surface properties of HBA(EO)80 aqueous solution systems were investigated using FF-TEM (freeze-fracture transmission electron microscope), negative-staining TEM technologies and DLS (dynamic light scattering) to investigate the aggregates’ morphologies.