Dynamic surface tension and dilational viscoelasticity of adsorption layers of alkylated chitosans and surfactant–chitosan complexes

The kinetics of the adsorption at the air-water interface and the processes of the structure formation inside the adsorption layers of hydrophobically modified systems [alkylated chitosans and sodium dodecyl sulfate (SDS)–chitosan (Ch) complexes] have been studied by the tensiometric method based on the axisymmetric rising-bubble-shape analysis as a function of the bulk concentration of polymers and the ageing time of their adsorption layers. The kinetics of the adsorption of chitosan, alkylated chitosans (ChC₃, ChC₈, and ChC₁₂), and surfactant–polyelectrolyte (PE) complexes formed by the chitosan and the polysoaps with oppositely charged anionic surfactant SDS is characterized by an induction time (the so-called lag time), τ_lag, corresponding to the diffusion stage of the formation of adsorption layers. During this time, the decrease in the surface tension (or the increase in the surface pressure π) does not exceed several millinewtons per meter that corresponds to the “gaseous” state of adsorption layers. The postlag stage of the formation of the adsorption layer is characterized by the remarkable rate of increase in the surface pressure π that corresponds to the conformational rearrangement of PEs inside the adsorption layer by increasing the number of hydrophobic groups (adsorbing centres) in contact with the non-polar phase at the interface. It has been found that during the lag time, the adsorption of alkylated chitosans (cationic polysoaps) increases with increasing alkyl chain length, whereas during the postlag time, the adsorption of the ChC₃ is maximal with regard to other polysoaps. It has been confirmed that at equal content of alkyl groups in the system, the surface activity of the SDS–Ch complexes is much higher with regard to that of the polysoaps. The viscoelasticity of adsorption layers of individual PEs and their complexes continuously increases with the ageing time, giving evidence for the interaction between the polymers inside the adsorption layers. It has been found that the rate of increase in the dilational storage module E′ of the adsorption layers of SDS–Ch complexes is much higher than for the polysoaps that correlates with the higher surface activity of the former with regard to the latter. For the mentioned systems, the module E′ is much higher than the loss module E″ that confirms the solid-like properties of their adsorption layers. On the other hand, the adsorption layers of the chitosan are liquid-like, while E′<<E′′.     

Complexation of hydrophobically modified polyelectrolytes with surfactants: anionic poly(maleic acid/octyl vinyl ether)/anionic sodium dodecyl sulfate

Interactions of surfactants with hydrophobically modified polyelectrolytes in aqueous solutions are important in several applications such as detergents, cosmetics, foods, and paints. Fundamental questions arise on the mechanisms of complexation of the polyelectrolyte and surfactant that control their behavior. In this work, the complexation was studied by examining interactions in aqueous solutions of a hydrophobically modified polymer, poly(maleic acid/octyl vinyl ether) (PMAOVE), with sodium dodecyl sulfate (SDS) by monitoring viscosity, pyrene solubility, light scattering, and analytical ultracentrifugation. When the anionic surfactant SDS was added to aqueous solutions of the similarly charged polymer PMAOVE, the surfactant was incorporated into the hydrophobic nanodomains of PMAOVE even far below the cmc of the surfactant. On the basis of viscosity, pyrene solubility, and analytical ultracentrifugation data, it is proposed that PMAOVE undergoes structural unfolding and at higher SDS concentrations mixed micelles are formed.     

Interactions between chitosan and SDS at a low-charged silica substrate compared to interactions in the bulk--the effect of ionic strength

The effect of ionic strength on association between the cationic polysaccharide chitosan and the anionic surfactant sodium dodecyl sulfate, SDS, has been studied in bulk solution and at the solid/liquid interface. Bulk association was probed by turbidity, electrophoretic mobility, and surface tension measurements. The critical aggregation concentration, cac, and the saturation binding of surfactants were estimated from surface tension data. The number of associated SDS molecules per chitosan segment exceeded one at both salt concentrations. As a result, a net charge reversal of the polymer-surfactant complexes was observed, between 1.0 and 1.5 mM SDS, independent of ionic strength. Phase separation occurs in the SDS concentration region where low charge density complexes form, whereas at high surfactant concentrations (up to several multiples of cmc SDS) soluble aggregates are formed. Ellipsometry and QCM-D were employed to follow adsorption of chitosan onto low-charged silica substrates, and the interactions between SDS and preadsorbed chitosan layers. A thin (0.5 nm) and rigid chitosan layer was formed when adsorbed from a 0.1 mM NaNO3 solution, whereas thicker (2 nm) chitosan layers with higher dissipation/unit mass were formed from solutions at and above 30 mM NaNO3. The fraction of solvent in the chitosan layers was high independent of the layer thickness and rigidity and ionic strength. In 30 mM NaNO3 solution, addition of SDS induced a collapse at low concentrations, while at higher SDS concentrations the viscoelastic character of the layer was recovered. Maximum adsorbed mass (chitosan + SDS) was reached at 0.8 times the cmc of SDS, after which surfactant-induced polymer desorption occurred. In 0.1 mM NaNO3, the initial collapse was negligible and further addition of surfactant lead to the formation of a nonrigid, viscoelastic polymer layer until desorption began above a surfactant concentration of 0.4 times the cmc of SDS.     

Comblike poly(ethylene oxide)/hydrophobic C6 branched chitosan surfactant polymers as anti-infection surface modifying agents

A series of structurally well-defined poly(ethylene oxide)/hydrophobic C₆ branched chitosan surfactant polymers that undergo surface induced self assembly on hydrophobic biomaterial surfaces were synthesized and characterized. The surfactant polymers consist of low molecular weight (M_w) chitosan backbone with hydrophilic poly(ethylene oxide) (PEO) and hydrophobic hexyl pendant groups. Chitosan was depolymerized by nitrous acid deaminative cleavage. Hexanal and aldehyde-terminated PEO chains were simultaneously attached to low M_w chitosan hydrochloride via reductive amination. The surfactant polymers were prepared with various ratios of the two side chains. The molecular composition of the surfactant polymers was determined by FT-IR and ¹H NMR. Surface active properties at the air–water interface were determined by Langmuir film balance measurements. The surfactant polymers with PEO/hexyl ratios of 1:3.0 and 1:14.4 were used as surface modifying agents to investigate their anti-infection properties. E. coli adhesion on Silastic^® surface was decreased significantly by the surfactant polymer with PEO/hexyl 1:3.0. Surface growth of adherent E. coli was effectively suppressed by both tested surfactant polymers.     

Stable and pH-sensitive nanogels prepared by self-assembly of chitosan and ovalbumin

Two natural macromolecules, chitosan and ovalbumin, were used to produce nanogels by a new, green, and convenient method. Chitosan and ovalbumin solutions were mixed; the pH of the resulting solution was adjusted; and the solution was successively stirred and heated. After that, ovalbumin gelled forming nanospheres. The chitosan chains are supposed to be partly trapped in the nanogel core upon heating because of the electrostatic attractions between chitosan and ovalbumin, while the rest of the chitosan chains should form the shell of the nanogels. The nanogels did not change the size distribution after long-time storage and did not dissociate in the pH range of 2-10.5. The dispersibility, size, and hydrophobicity/hydrophilicity of the nanogels are pH-dependent. The nanogels are good candidates for cosmetic and pharmaceutical applications.     

Vesicle--biopolymer gels: networks of surfactant vesicles connected by associating biopolymers

The effect of adding an associating biopolymer to surfactant vesicles and micelles is studied using rheology and small-angle neutron scattering (SANS). The associating polymer is obtained by randomly tethering hydrophobic alkyl chains to the backbone of the polysaccharide, chitosan. Adding this polymer to surfactant vesicles results in a gel; that is, the sample transforms from a Newtonian liquid to an elastic solid having frequency-independent dynamic shear moduli. SANS shows that the vesicles remain intact within the gel. The results suggest a gel structure in which the vesicles are connected by polymer chains into a three-dimensional network. Vesicle-polymer binding is expected to occur via the insertion of polymer hydrophobes into the vesicle bilayer. Each vesicle thus acts as a multifunctional junction in the network structure. Significantly, gel formation does not occur with the native chitosan that has no hydrophobes. Moreover, adding the hydrophobically modified chitosan to a viscous sample containing wormlike micelles increases the viscosity further but does not give rise to a gel-like response. Thus, the formation of a robust gel network requires both the presence of hydrophobes on the polymer and vesicles in solution.     

Binding of surfactants to hydrophobically modified polymers

Recent progress in the understanding of the binding of surfactants to hydrophobically modified polymers (HMP), and the consequences of such binding, is reviewed. HMP are water-soluble polymers onto which low proportions of hydrophobic sidechains (hydrophobes) have been grafted. In an aqueous environment, the HMP hydrophobes associate among themselves and with added surfactant molecules into micelle-like aggregates. An HMP may therefore be considered as a ‘modified surfactant’, and the binding of surfactants to HMP is analogous to the mixed micellisation in mixed surfactant solutions. The binding isotherm gives the concentration of free (monomeric) surfactant and the stoichiometry of the HMP/surfactant complex at different total compositions. In mixtures involving ionic surfactants, it is found that the free surfactant often dominates, and gives important contributions to the ionic strength. Characteristic properties of HMP/surfactant mixtures may be related to stoichiometries of the mixed complexes. Thus, the maximum in solution viscosity, which is commonly found in HMP/surfactant mixtures, occurs at a similar hydrophobe stoichiometry (ratio of bound surfactant to HMP hydrophobe) for many different systems, although the total concentrations of surfactant at the maximum may vary by orders of magnitude, depending on the surfactant cmc. The solubility of a complex of oppositely charged HMP and surfactant is related to the charge stoichiometry of the complex. The phase separation/redissolution phenomena occurring in the bulk solution influence the HMP adsorption to surfaces and the forces between surfaces with adsorbed HMP.     

Functionalization of chitosan polymer and their applications

The deacetylated derivative of chitin i.e. chitosan is an advantageous and interesting bioactive polymer. Despite its biodegradability, it consists of many reactive primary and secondary hydroxyl (–OH) and amino (–NH₂) functional groups which allow the possibilities of chemical modifications. The several chemical modifications such as alkylation, acylation, quaternization, phthaloylation, sulfation, thiolation, carboxymethylation, graft copolymerization etc. carried out. The chemical modification results various types of derivatives with modified properties for specific applications in varied area mainly of pharmaceutical, biomedical, biotechnological, cosmetic, agricultural, food and non-food industries as well as in water treatment, paper, and textile industry. The ability of chitosan to undergo versatile modifications and applications presents a great opportunity to scientific community and to industry.     

Polyelectrolyte-surfactant complexes with long range order

Mixtures of carboxymethyl cellulose (CMC) or hydrophobically modified CMC with an oppositely charged surfactant (benzyldimethyltetradecylammonium chloride) in water were prepared. When the global polymer concentration is 0.18% by weight and the surfactant content is high enough, a precipitate with hexagonal order is formed. The precipitate composition shows practically constancy in its water content and a slight diminution in polymer concentration when the global surfactant content is varied between 0.9 and 23 wt%. The lattice parameter in this phase decreases when the polymer/surfactant ratio in the phase increases; this variation is faster with CMC than with the hydrophobically modified CMC. In this way electrostatic and hydrophobic interactions are far from being additive. From the extrapolation to infinite dilution, the global interaction seems to depend on the substitution degree in the polymer. Additionally, the comparison between the radius at the polar-apolar interface in the cylinders and the lattice parameter as a function of polymer/surfactant ratio in the hexagonal phase is compatible with some of the alkyl chains belonging to the hydrophobically modified CMC being present in the aqueous zone.     

Chitosan based surfactant polymers designed to improve blood compatibility on biomaterials

We developed chitosan based surfactant polymers that could be used to modify the surface of existing biomaterials in order to improve their blood compatibility. These polymers consist of a chitosan backbone, PEG side chains to repel non-specific protein adsorption, and hexanal side chains to facilitate adsorption and proper orientation onto a hydrophobic substrate via hydrophobic interactions. Since chitosan is a polycationic polymer, and it is thrombogenic, the surface charge was altered to determine the role of this charge in the hemocompatibility of chitosan. Charge had a notable effect on platelet adhesion. The platelet adhesion was greatest on the positively charged surface, and decreased by almost 50% with the neutralization of this charge. A chitosan surface containing the negatively charged SO(3)(-) exhibited the fewest number of adherent platelets of all surfaces tested. Coagulation activation was not altered by the neutralization of the positive charge, but a marked increase of approximately 5-6 min in the plasma recalcification time (PRT) was displayed with the addition of the negatively charged species. Polyethylene (PE) surfaces were modified with the chitosan surfactant resulting in a significant improvement in blood compatibility, which correlated to the increasing PEG content within the polymer. Adsorption of the chitosan surfactants onto PE resulted in approximately an 85-96% decrease in the number of adherent platelets. The surfactant polymers also reduced surface induced coagulation activation, which was indicated by the PEG density dependent increase in PRTs. These results indicate that surface modification with our chitosan based surfactant polymers successfully improves blood compatibility. Moreover, the inclusion of either negatively charged SO(3)(-) groups or a high density of large water-soluble PEG side chains produces a surface that may be suitable for cardiovascular applications.     

The Fast Relaxation Process between Hydrophobically Modified Associating Polyacrylamide and Different Surfactants at the Water‐Octane Interface

In our previous work (Macromolecules 2004, 37:2930), we found that the hydrophobic blocks of polyacrylamide modified with 2‐phenoxylethyl acrylate (POEA) and anionic surfactant sodium dodecyl sulfate (SDS) may form mixed associations at octane/water interface. However, the process involving the exchange of surfactant molecules between monomers and mixed associations in interface is so fast that we cannot obtain its characteristic time. In this article, the interfacial dilational viscoelastic properties of another hydrophobically associating block copolymer composed of acrylamide (AM) and a low amount of 2‐ethylhexyl acrylate (EHA) (<1.0 mol%) at the octane‐water interfaces were investigated by means of oscillating barriers method and interfacial tension relaxation method respectively. The influences of anionic surfactant SDS and nonionic surfactant Triton X‐100 on the dilational viscoelastic properties of 7000 ppm polymer solutions were studied. The results showed that the interaction between P(AM/2‐EHA) and SDS was similar to that of P(AM/POEA) and SDS. Moreover, we got the relaxation characteristic time of the fast process involving the exchange of s Triton X‐100 molecules between monomers and mixed associations.

We also found that the interfacial tension response of hydrophobically associating water‐soluble copolymers to the sinusoidal oscillation of interfacial area at low bulk concentration is as same as that of the typical surfactants: the interfacial tension decreases with the decrease of interfacial area because of the increase of interfacial active components. However, the interfacial tension increases with the decrease of interfacial area at 7000 ppm P(AM/2‐EHA), which is believed to be correlative with the structure of absorbed film. The results of another hydrophobically associating polymer P(AM/POEA) and polyelectrolyte polystyrene sulfonate (PSS) enhanced our supposition. The phase difference between area oscillation and tension oscillation has also been discussed considering the apparent negative value.     

Vitamin A and vitamin E interaction behavior on chitosan microspheres

Chitosan is a biodegradable natural polymer with great potential for pharmaceutical applications due to its biocompatibility, high charge density, and non-toxicity. In this study, chitosan microspheres were successfully prepared by an adapted method of coagulation/dispersion. The degree of deacetylation of chitosan powder was obtained by NMR ¹H and FTIR techniques. Chitosan powder and chitosan microspheres were characterized by BET surface area and scanning electron microscopy (SEM). The interactions among the chitosan microspheres and the vitamins A and E were characterized by FTIR. In order to evaluate the ability of interaction of vitamin A and vitamin E with the chitosan microspheres, the thermodynamic parameters were followed by calorimetric titration. Different experimental approaches were applied, such as adsorption isotherms, kinetics and thermodynamics studies. The obtained results showed that the interactions of chitosan microspheres with the vitamins were spontaneous, enthalpically and entropically favorable, indicating that the chitosan microspheres can be used with success in the controlled release of these vitamins.     

Adsorption of cationic cellulose derivative/anionic surfactant complexes onto solid surfaces. II. Hydrophobized silica surfaces

The effect of the anionic surfactant SDS (sodium dodecyl sulfate) on the adsorption behavior of cationic hydroxyethyl cellulose (Polymer JR-400) and hydrophobically modified cationic cellulose (Quatrisoft LM-200) at hydrophobized silica has been investigated by null ellipsometry and compared with the previous data for adsorption onto hydrophilic silica surfaces. The adsorbed amount of LM-200 is found to be considerably larger than the adsorbed amount of JR-400 at both surfaces. Both polymers had higher affinity toward hydrophobized silica than to silica. The effect of SDS on polymer adsorption was studied under two different conditions: adsorption of polymer/SDS complexes from premixed solutions and addition of SDS to preadsorbed polymer layers. Association of the surfactant to the polymer seems to control the interfacial behavior, which depends on the surfactant concentration. For the JR-400/SDS complex, the adsorbed amount on hydrophobized silica started to increase progressively from much lower SDS concentrations, while the adsorbed amount on silica increased sharply only slightly below the phase separation region. For the LM-200/SDS complex, the adsorbed amounts increased progressively from very low SDS concentrations at both surfaces, and no large difference in the adsorption behavior was observed between two surfaces below the phase separation region. The complex desorbed from the surface at high SDS concentrations above the critical micelle concentration. The reversibility of the adsorption of polymer/SDS complexes upon rinsing was also investigated. When the premixed polymer/SDS solutions at high SDS concentrations (>5 mM) were diluted by adding water, the adsorbed amount increased due to the precipitation of the complex. The effect of the rinsing process on the adsorbed layer was determined by the hydrophobicity of the polymer and the surface.     

The effect of surfactants on adsorbed layers of a cationic polyelectrolyte

A comparative study of the influence of anionic (sodium dodecyl sulfate, SDS), cationic (tetradecyltrimethylammonium bromide, TTAB) and non-ionic (penta-ethyleneglycol mono n-dodecyl ether, C₁₂E₅) surfactants on the structure and composition of adsorbed layers of cationic hydrophobically modified hydroxyethylcellulose (Quatrisoft LM 200) on hydrophilic surfaces (mica and silica) was carried out using surface force apparatus andin situ null ellipsometry. It is shown that a complex interplay of electrostatic, hydrophobic, and steric effect govern polymer/surfactant/surface interactions and that the effect of surfactant addition strongly depends on its nature and concentration.Both anionic and non-ionic surfactants exhibit aggregation on the polymer hydrophobes. SDS has the most profound influence on Quatrisoft interfacial behavior due to the changes in electrostatics accompanying formation of the polymer/surfactant complex. In the case of C₁₂E₅, large surfactant clusters bound to the polymer affect the macromolecules' conformation in the adsorbed layer via steric effects. In contrast to SDS and C₁₂E₅, no evidence of interaction between the polycation and a like-charged surfactant, TTAB, was obtained. At the same time, TTAB adsorbs on the surface in competition with the polyelectrolyte. This results in partial displacement of the latter and its looser attachment to the surface.     

Preparation of electrospun chitosan/poly(vinyl alcohol) membranes

Electrospinning of chitosan from its solutions in 2% aqueous acetic acid was studied by adding poly(vinyl alcohol) (PVA) as a “guest” polymer. Properties of the chitosan/PVA solutions including viscosity, conductivity, and surface tension were measured, and effects of the polymer concentration, chitosan/PVA mass ratio and processing parameters (applied voltage, flow rate, capillary-to-collector distance) on the electrospinnability of chitosan/PVA were investigated. Analyses of scanning electron micrographs and transmission electron micrographs suggested that the chitosan/PVA ultrafine fibers were often obtained along with beads, and chitosan was located in the elctrospun fibers as well as in the beads. Uniform chitosan/PVA fibers with an average diameter of 99 ± 21 nm could be prepared from a 7% chitosan/PVA solution in 40:60 mass ratio. Results of Fourier transform infrared spectroscopy and X-ray diffraction demonstrated that there were possible hydrogen bonds between chitosan and PVA molecules, which could weaken the strong interaction in chitosan itself and facilitate chitosan/PVA electrospinnability. The electrospun chitosan/PVA membranes showed higher water uptake and would have potential applications in wound dressings.     

Influence of pH, ionic strength, and temperature on self-association and interactions of sodium dodecyl sulfate in the absence and presence of chitosan

Chitosan is a cationic biopolymer that has many potential applications in the food industry because of its unique nutritional and physicochemical properties. Many of these properties depend on its ability to interact with anionic surface-active molecules, such as surfactants, phospholipids, and bile acids. The purpose of this study was to examine the influence of pH (3 and 7), ionic strength (0-200 mM NaCl), and temperature (10-50 degrees C) on the interactions between a model anionic surfactant (sodium dodecyl sulfate, SDS) and chitosan using isothermal titration calorimetry, selective surfactant electrode, and turbidity measurements. At pH 3 and 30 degrees C, SDS bound strongly to chitosan to form an insoluble complex that contained about 4-5 mmol of SDS/1 g of chitosan at saturation. When SDS and chitosan were mixed at pH 7 they did not interact strongly, presumably because the biopolymer had lost most of its positive charge at this pH. However, when SDS and chitosan were mixed at pH 3 and then the solution was adjusted to pH 7, the SDS remained bound to the chitosan. The presence of NaCl (0-200 mM) in the solutions decreased the critical micelle concentration (cmc) of SDS (in both the absence and the presence of chitosan) but had little influence on the amount of SDS bound to chitosan at saturation. The cmc of SDS and the amount of SDS bound to the chitosan at saturation were largely independent of the holding temperature (10-40 degrees C). Nevertheless, the enthalpy changes associated with micelle dissociation were highly temperature-dependent, indicating the importance of hydrophobic interactions, whereas the enthalpy changes associated with SDS-chitosan binding were almost temperature-independent, indicating the dominant contribution of electrostatic interactions. This study provides information that may lead to the rational design of chitosan-based ingredients or products with specific nutritional and functional characteristics, for example, cholesterol lowering.     

疏水化水溶性两性纤维素接枝共聚物与粘土的相互作用

运用紫外光谱法研究了疏水化水溶性两性纤维素接枝共聚物(羧甲基纤维素接枝丙烯酰胺及N,N 二甲基辛基(2 甲基丙烯酰氧乙基)溴化铵的共聚物, CGAO)在粘土上的吸附,考察了聚合物浓度、无机盐浓度、温度、 pH、 表面活性剂和粘土浓度等因素对CGAO在粘土上吸附量的影响,以及通过X射线衍射分析了CGAO在粘土上的吸附位置.结果表明， CGAO在粘土上的吸附规律与一般聚合物有很大差别,而且CGAO未深入到粘土晶层间,只在其表面吸附. 粘土与CGAO作用前后的粒度分析表明CGAO对粘土粒子有很好的桥接聚集作用. 扫描电镜分析显示粘土与CGAO作用后,其颗粒形态发生了显著变化.     

Emulsification properties of chitosan

 The chitosans use as an emulsifier in food emulsions was explored. The properties of chitosan (air/solution surface activity, electrical conductivity, HLB) were studied. The obtained emulsions were stable multiple w/o/w emulsions, whose characteristics were explained on the basis of the emulsifier structure and solution properties. The reaction with an anionic surfactant, sodium dodecylsulfate, was also studied, giving a water-insoluble complex at a given surfactant/chitosan ratio. Received: 24 March 1998 Accepted: 13 July 1998     

Solution properties of hydrophobically modified acrylamide-based polysulfobetaines in the presence of surfactants

Polymer–surfactant interactions in aqueous solutions of a acrylamide-based, hydrophobically modified polysulfobetaine (ADS) containing 3-[N-(2-methacryloxylethyl)-N,N-dimethylammonio]-propane sulfonate and stearyl methylacrylate, with sodium dodedyl sulfate (SDS), N-dodecyl-N,N,N-trimethylammonium bromide (DTAB), and Triton X-100 were studied using surface tension, rheology, Rayleigh light scattering, and dynamic laser light scattering techniques. The purpose of this study was to highlight the influences of the surfactant structure and the nature of the surfactant head group on the polymer–surfactant interactions. The results show that the interaction and association between ADS and surfactants are distinctly varied depending on surfactant type and surfactant concentration. SDS produced the strongest interactions with ADS, while DTAB and Triton X-100 interact with ADS to a lesser degree, which is attributed to surfactant structure and the nature of the surfactant head group. For SDS and DTAB, there are two driving forces for the complexation of the polymer and surfactants, resulting from the electrostatic interaction and the hydrophobic association. However, for the nonionic surfactant Triton X-100, only hydrophobic association predominated in the interaction between ADS and the surfactant. The mechanism and reconstruction of the polymer–surfactant complexes have been evaluated and discussed.     

Modified polysaccharides for use in enhanced oil recovery applications

Aqueous solutions of a charged hydrophobically modified hydroxyethylcellulose (HM-HEC(−)) exhibit high viscosities even at low polymer concentrations (0.2 wt%), which is an interesting feature in connection with enhanced oil recovery. This polymer was synthesized for this work. Effects of temperature and addition of sodium dodecyl sulfate (SDS) or hydroxypropyl-β-cyclodextrin (HP-β-CD) on the viscosity properties of a semidilute solution of HM-HEC(−) are examined. The results for the HM-HEC(−)/SDS system disclose strong interactions between HM-HEC(−) and SDS at low level of SDS addition, and this leads to a significant viscosification of the polymer-surfactant mixture. At higher surfactant concentrations the association complexes are disrupted. A strong temperature effect of the viscosity is observed at moderate levels of SDS addition, with lower values of the viscosity at elevated temperatures because of enhanced polymer chain mobility that breaks up the associations. Addition of HP-β-CD monomers to the HM-HEC(−) solution generates decoupling of associations via inclusion complex formation with the polymer hydrophobic tails and the viscosity decreases. By using temperature and addition of these co-solutes, it is demonstrated that the viscosity of the polymer solution can be tuned over a large range of viscosity values.