Photophysical and rheological properties of naphthalene-labeled cationic poly(dimethyl sulfate quaternized acrylamide/N,N-dimethylaminopropylmaleimide copolymer)

The synthesis, rheological, and fluorescence properties of a cationic water-soluble copolymer, naphthalene-labeled cationic poly(dimethyl sulfate quaternized acrylamide/N,N-dimethylaminopropylmaleimide copolymer), poly(DSQADMAPM)/NA, are reported. When fluorescent hydrophobes (naphthyl group) are incorporated into the cationic copolymer, the photophysical response may effectively probe solution behavior on the microscopic level. The salt and pH responsiveness inherent to the cationic copolymer systems is a function of ionic group type. Experimental results indicate that I_E/I_M increases steadily with increases in polymer concentration and I_E/I_M values for a given polymer concentration are higher in salt. At low pH values, I_E/I_M is high and excimer emission increases as the quaternary amino groups (R₄N⁺) are screened out. Dynamic light scattering (QELS) measurements indicate that diffusion coefficients of the cationic copolymer increase and the hydrodynamic diameters decrease with increasing salt concentration. Viscosity studies reveal that the polymer coil shrinks as salt is added. In fluorescence quenching study, the reduction in the quenching efficiency of thallium (Tl⁺) with salt addition can arise from enhanced compartmentalization of naphthalene labels as added electrolyte enhances intrapolymer micellization. The intrapolymer micelle is easily formed, indicating that the thallium ion has difficulty in reacting with bound naphthalenes located in the shrunk polymer coil. The cationic copolymer is depicted as an expanded polymer coil in deionized water because of intra- and interchain repulsions. Consequently, salt addition breaks down the repulsions and enhances intrapolymer micellization. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36 : 11–19, 1998     

Effect of salt and surfactant on aqueous solution properties of pyrene-labeled poly(3-dimethyl (methylmethacryloyl ethyl) ammonium propane sulfonate)

Photophysical and solution properties of pyrene-labeled poly(3-dimethyl(methylmethacryloyl ethyl) ammonium propane sulfonate), poly(DMAPS/Py), were studied in terms of fluorescence emission measurement. The I_E/I_M was shown as a function of polymer concentration in deionized water. I_E/I_M value decreases with an increase in the salt concentration. The addition of surfactants to the aqueous solution of poly(DMAPS/Py) can either induce the mixed micelle of intra-polymer and its surrounding surfactants and/or mixed micelle of inter-polymers and their surrounding surfactants. Models of interactions between poly(DMAPS/Py) and surfactant or divalent salt in aqueous solution are proposed.     

Correlation of architecture with excimer emission in 100% pyrene‐labeled self‐assembled polymers

Pyrene was incorporated as pendant unit to side‐chain urethane methacrylate polymers having a short ethyleneoxy or a long polyethyleneoxy spacer segment. The short‐spacer pyrene urethane methacrylate was also incorporated either as block or random copolymer (1:9) along with polystyrene. The excimer emission was observed to be different for different polymers with the random copolymer exhibiting the lowest efficiency. But, the total quantum yield was highest (? = 0.58) for random copolymer due to the high emission coefficient of monomer compared to that of excimer. The polymer dynamics were compared by steady state emission and fluorescence decay in THF or THF/water (9:1) solvent mixture and films. The solid state decay profile showed decay without a rise time indicating presence of ground state aggregates. In THF/water (9:1), the decay profile at the excimer emission (500 nm) showed a rise time indicating dynamic excimers. The evolution of excimeric emission centred ～430 or ～480 nm as a function of temperature was also studied in THF/water (9:1). The I_E/I_M ratio for the λ_{343 nm} excitation exhibited steady increase with temperature with the block copolymer PS‐b‐PIHP exhibiting the highest ratio and highest rate of increase; whereas, the random copolymer PS‐r‐PIHP had the lowest I_E/I_M ratios. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Synthesis, characterization and flocculation performance of zwitterionic copolymer of acrylamide and 4-vinylpyridine propylsulfobetaine

A novel zwitterionic polyacrylamide AMVPPS copolymer containing sulfobetaine groups was synthesized by copolymerizing acrylamide (AM) and 4-vinylpyridine propylsulfobetaine (4-VPPS) in 0.5 mol/L NaCl solution with potassium persulfate (K₂S₂O₈) and sodium bisulfite (NaHSO₃) as initiator. The structure and composition of AMVPPS copolymer were characterized by FT-IR spectroscopy, ¹H NMR and elemental analyses. Thermal stability and solution properties of AMVPPS copolymer were studied by thermogravimetry analysis (TGA) and viscometry. Anti-polyelectrolyte behavior was observed and was found to be enhanced with increasing 4-VPPS content in copolymer. The flocculation performance for 2.5 g/L kaolin suspension and 2.5 g/L hematite suspension was evaluated by transmittance measurement and phase contrast microscopy. The effects of 4-VPPS content in the copolymer, intrinsic viscosity and the added salt on the flocculation performance were investigated. It was found that AMVPPS copolymer was a good flocculant for both anionic kaolin and cationic hematite suspensions and the flocculation performance of copolymer was much better than that of pure polyacrylamide (PAM). A very wide range of the optimum flocculation concentration, named as “flocculation window”, was found for both suspensions. These flocculation characteristics were mainly dependent on the charge neutralization, the intragroup conformation transition from water to NaCl solution and then the interchain bridging of the zwitterionic AMVPPS copolymer.     

Micellar parameters of diblock copolymers and their interactions with ionic surfactants

The interactions of non-ionic amphiphilic diblock copolymer poly（oxyethylene/oxybutylene）(E₃₉B₁₈) with anionic surfactant sodium dodecyl sulphate（SDS） and cationic surfactant hexadecyltrimethylammonium bromide（CTAB） were studied by using various techniques such as surface tension,conductivity,steady-state fluorescence and dynamic light scattering.Surface tension measurements were used to determine the critical micelle concentration（CMC） and thereby the free energy of micellization(△G_mic),free energy of adsorption(△G_ads),surface excess concentration（Γ） and minimum area per molecule（A）.Conductivity measurements were used to determine the critical micelle concentration（CMC）,critical aggregation concentration（CAC）,polymer saturation point（PSP）,degree of ionization（α） and counter ion binding（β）. Dynamic light scattering experiments were performed to check the changes in physiochemical properties of the block copolymer micelles taken place due to the interactions of diblock copolymers with ionic surfactants.The ratio of the first and third vibronic peaks（I₁/I₃） indicated the polarity of the pyrene micro environment and was used for the detection of micelle as well as polymer-surfactant interactions.Aggregation number（N）,number of binding sites（n） and free energy of binding （△G_b） for pure surfactants as well as for polymer-surfactant mixed micellar systems were determined by the fluorescence quenching method.     

TEMPERATURE DEPENDENCE OF THE FLUORESCENCE SPECTRA OF LADDERLIKE POLYPHENYLSILSESQUIOXANE AND LADDERLIKE 1,4-PHENYLENE-BRIDGED POLYVINYLSILOXANE

Fluorescence spectra of ladderlike polyphenylsilsesquioxane (LPPS) and ladderlike 1,4-phenylene-bridgedpolyvinylsiloxane (LPPVS) have been measured as a function of temperature (4-55℃), in dilute tetrahydrofuran solution.The excimer (I_E) to monomer (I_M) intensity ratio (I_E/I_M) of LPPS dilute solution shows a double linear Arrhenius plot with abreak point ascribable to a transition temperature T_t This behavior has not been found for single chain polyorganosiloxanes.When InI_E of LPPS was plotted against I/T it also gave a double linear plot with one break point, which was found in singlechain polyorganosiloxanes. The different behaviors between LPPS and single chain polyorganosiloxanes may be mainlyattributed to the relatively rigid double-chain macromolecular backbone of LPPS. However, the In(I_E/I_M) of dilute LPPVSsolution versus I/T shows a simple linear variation with a positive slope which confirms our proposition. The differencebetween the fluorescence results of LPPS and those of LPPVS may possibly derive from their structure differences andcooperative motion in backbone chain bonds.     

Synthesis, Characterization and Solution Properties of Hydrophobically Modified Polyelectrolyte Poly(AA-co-TMSPMA)

The hydrophobically modified polyelectrolyte was synthesized using precipitation polymerization of acrylic acid and 3-[tris(trimethylsilyloxy)silyl]propyl methacrylate (TMSPMA) in various molar ratios in supercritical carbon dioxide. FT-IR, ¹H NMR, capillary viscometry, rotational viscometer, transmission electron microscopy and fluorescence spectroscopy were used to characterize this copolymer. The viscosity of the copolymers showed a strong dependence on pH with a maximum at pH=5.5. Associating morphologies of the copolymer were observed by TEM. Associating morphologies of poly(AA-co-TMSPMA) solution changed from a global structure to a shell-core structure with increasing hydrophobic levels. A solution of sample PAT4 with a shell-core structure had the largest viscosity value. In addition, the critical micelle concentration of copolymer solution, cmc, was determined from the relative viscosity. The critical micelle concentration was further confirmed by fluorescence spectroscopy using 1-pyrenemethylamine hydrochloride, PyMeA⋅HCl, as a cationic fluorescent probe. The cmc was determined from the intensity ratios, the first to the third emission peaks I ₁/I ₃, and the excimer to monomer I _E/I _M ratio of the pyrene probe as a function of concentration.     

Pyrene fluorescence measurements of metastable oil droplets in surfactant-free oil-in-water emulsions

 The fluorescence behavior of pyrene in oil droplets of a surfactant-free oil-in-water emulsion was studied for benzene, fluorobenzene, n-hexane and cyclohexane droplets in water. The excimer–monomer fluorescence ratio immediately after sonication, I _E/I _M(0), of the benzene/water emulsion was 8–10 times larger than for the benzene solution. The ratio I _E/I _M(t) increased in the first 10–20 min before it decreased to zero. Similar behavior was observed for the fluorobenzene/water emulsion, while I _E/I _M(0) for emulsions with n-hexane and cyclohexane was smaller than for benzene and fluorobenzene/water emulsions. I _E/I _M(t) hardly changed with time for the n-hexane and cyclohexane/water emulsions. This different behavior was attributed to the increased solubility of nanometer-size droplets with benzene and fluorobenzene. Received: 20 June 2001 Accepted: 19 April 2001     

Configurations conducive to the formation of intramolecular excimers in poly(N‐vinyl carbazole) and its copolymers

The ratios of the intensity of excimer and monomer emissions, denoted I_E/I_M, in poly(N‐vinyl carbazole) and copolymers of N‐vinyl carbazole and methyl methacrylate were measured with steady‐state fluorescence. Measurements were performed in dilute solutions of several fluid solvents at 25 °C and in a solid matrix of poly(methyl methacrylate) at room temperature. The values of I_E/I_M depended on the nature of the solvent, the emission wavelength, and the copolymer composition. Molecular dynamics simulations were performed for diastereoisomers of 2,4‐di(N‐carbazolyl)pentane and for isotactic and syndiotactic trichromophoric copolymer fragments to assist in the identification of the thermally accessible conformations capable of forming intramolecular excimers and the configurational relationship of the carbazole units in these complexes. Nearest neighbor carbazole groups made the dominant contribution to the excimers. Excimers were more likely in isotactic sequences than in syndiotactic sequences, as was also the case for the low‐energy excimer arising from the complete overlap of two carbazole units. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 1272–1281, 2001     

AMPHIPHILIC COPOLYMERS AS MEDIA FOR LIGHT-INDUCED ELECTRON TRANSFER–I. ELECTROSTATIC EFFECT ON THE FORWARD REACTION AS STUDIED BY FLUORESCENCE QUENCHING

Abstract— Fluorescence quenching of amphiphilic copolymers, poly(9-vinylphenanthrene-co-sodium 2-acrylamido-2-methylpropanesulfonate) (APh) and poly(9-vinylphenanthrene-co-3-methacrylamidopropyltrimethylammonium methyl sulfate) (QPh), in aqueous solution, was studied using methyl viologen (MV²⁺) or 4,4'-bipyridinium-1, 1'-bis(trimethylenesulfonate) (SPV) as oxidative quenchers. The fluorescence of the excited phenanthrene groups in APh was found to be efficiently quenched by MV²⁺. The apparent second-order rate constant for the quenching, k_q, ranged in the magnitude of 10¹¹ -10¹²M^-1 s^-1, which are well beyond the diffusion-controlled limit. This is presumably due to an increase of the effective concentration of MV²⁺ around the fluorophore in the copolymer resulting from electrostatic attraction between MV²⁺ and anionic segments of APh. This strong electrostatic interaction also favors the formation of ground-state EDA (electron donor acceptor) complex between the phenanthrene residue and MV²⁺. Such striking behaviors were not observed with the related model compound. Unexpectedly, the quenching with SPV, a zwitterionic quencher, was also enhanced in the polymer system (k_q= 2–6 × 10¹⁰M^-1 s^-1), suggesting the presence of some attractive interaction between APh and SPV. Contrary to the APh system, the fluorescence quenching of the corresponding cationic polymer (QPh) with MV²⁺ was strongly diminished (k_q= 5 × 10⁸M^-1 s^-1). This indicates that the polycation of QPh effectively prevents the access of MV²⁺ to the polymer.     

Participation of water in conformational change of isotactic poly(2-hydroxyethyl methacrylate) as studied by viscometry in various electrolytic solutions

Conformational properties of isotactic poly(2-hydroxyethyl methacrylate) (PHEMA) have been studied by viscometry in various electrolytic solutions. The intrinsic viscosity of isotactic PHEMA at 0.01M salt solution increases with decreasing the B coefficient in Jones—Dole's equation. In respective to water structures, a polymer chain is more expanded in the salt solution including water structure breaker ions. As the concentration of ions increases, the interactions between polymer segments and ions make a major contribution to conformational changes of isotactic PHEMA. Depending on the kind of ions, a salting-in or out effect is observed at higher concentrations than 0.1M salt solution. We observed that the denaturing effects of various anions in isotactic PHEMA salt solutions are as follows; SO₄^2- < F^? < I^? NO₃^? < SCN^-. This order is similar to the Hofmeister series. To investigate the influences of denaturing agents on solvent structures, we also compared the guanidine hydrochloride effect with the tetrabutylammonium chloride effect in isotactic PHEMA solution.     

pH‐Responsive PEG‐Poly(β‐amino ester) Block Copolymer Micelles with a Sharp Transition

Summary: A pH‐sensitive block copolymer is synthesized by step polymerization and its pH‐sensitive micellization‐demicellization behavior is studied. This polymer has a hydrophilic MPEG (shell) and hydrophobic but pH‐sensitive poly(β‐amino ester) (core), which can form a self‐assembled micelle. As confirmed by fluorescence spectroscopy and dynamic light scattering (DLS), this polymer shows a sharp pH‐sensitive micellization‐demicellization behavior. It is confirmed that the pH sensitivity is affected by the molecular weight ratio between the MPEG and poly(β‐amino ester).

Plots of the intensity ratio I₃₃₇/I₃₃₄ (from pyrene excitation spectra): a) vs. pH for copolymer samples and b) vs. log (concentration) for M1.     

Effect of Hydrophilic/Hydrophobic Block Ratio and Temperature on the Surface and Associative Properties of Oxyethylene and Oxybutylene Diblock Copolymers in Aqueous Media

Recent development in dispersion science and technology demands block copolymers with a variable block length and composition. To highlight that purpose, the surface active, associative, colloidal, and thermodynamic behavior of three diblock copolymers having different hydrophilic to hydrophobic ratio is reported here. Using surface tension and light scattering measurements, the micellization and adsorption behavior of polyoxyethylene and polyoxybutylene diblock copolymers of the type E_mB_n have been analyzed. Critical micelle concentration (CMC) and related thermodynamic parameters like free energy (ΔG_mic), enthalpy (ΔH_mic), and entropy (ΔS_mic) of micellization were calculated from CMC value using the closed association model. Likewise, the surface active parameters, like surface excess concentration (Γ₂), area per molecule (A₂), and thermodynamic parameters such as free energy (ΔG_ads), enthalpy (ΔH_ads), and entropy (ΔS_ads) of adsorption of polymer at the air/water interface, were also calculated at various temperatures. Static and dynamic light scattering techniques were employed for the determination of the weight-average molar (M_w), association number (N_w), polymer–water interaction (A₂), and micellar size in terms of hydrodynamic radii (R_h) of copolymer micelles. The effect of block length and solution temperature on the surface and micellar properties of these copolymers was also investigated.     

Photophysical characterization of mixed micelles of n-butanol/SDS and n-hexanol/SDS. A study at low alcohol concentrations

 The effect of the addition of n-butanol (BuOH) and n-hexanol (HexOH) on the micellization of sodium dodecylsulfate (SDS) has been investigated using fluorescence quenching methods. The binding constants were calculated using an expression which relates the total concentration of alcohols and the micelle concentration. The values of K were 4.67 and 17.6 M^-1 for BuOH/SDS and HexOH/SDS, similar to values obtained by other methods. The cmc of SDS decreases on addition of alcohols and goes through a minimum for the BuOH/SDS system. Micellar aggregation numbers (N) were determined from linear plots of Ln (I ⁰/I) against [Quencher] at low alcohol concentrations. For 15 mM SDS, in the presence of BuOH the N values decrease on addition of alcohol up to 0.2 M. For HexOH, N can be assumed to be constant up to 4.8 mM, after which N decreases. The polarity of the micellar core containing alcohol was evaluated from the I ₁/I ₃ ratio of monomeric pyrene. The effect of addition of the alcohol causes a decrease in the I ₁/I ₃, which corresponds to a decrease in the polarity of the pyrene solubilization site. Received: 28 October 1996 Accepted: 10 January 1997     

Interaction of cetyltrimethylammonium bromide and poly(2-(acrylamido)-2-methylpropanesulfonic acid) in aqueous solutions determined by excimer fluorescence

 The binding interaction of the cationic surfactant cetyltrimethylammonium bromide (CTAB) and anionic poly(2-(acrylamido)-2-methylpropanesulfonic acid) (PAMPS) in dilute aqueous solutions was studied using the excimer fluorescent emission of the cationic probe 1-pyrenemethylamine hydrochloride (PyMeA·HCl). In the absence of CTAB, the saturation binding of PyMeAH⁺ on PAMPS is about 2.4 AMPS repeat units for one probe cation as determined by the relative emission intensity, I _E/I _M, of the excimer to monomer. With increasing CTAB concentration, I _E/I _M firstly increases, reaches a maximum, then decreases to zero. The I _E/I _M maximum indicates a critical aggregation concentration (cac) of 10⁻⁵ mol/l for CTAB in PAMPS solutions. The CTAB concentration at which I _E/I _M is zero is exactly equal to the PAMPS concentration, indicating that the probe cation is thoroughly excluded from the binding site of PAMPS by the CTAB cation and the equivalent stoichiometric aggregation is formed between CTAB and PAMPS. The blueshift of the excimer emission and the excitation spectra shows that the decrease of I _E/I _M with increasing CTAB concentration above the cac is caused mainly by the decrease of the static excimer. Received: 26 July 2000 Accepted: 23 November 2000     

Preparation of zwitterionic sulfobetaine end‐functionalized poly(ethylene glycol)‐b‐poly(caprolactone) diblock copolymers and examination of their thermogelling properties

To investigate thermogelling behavior, in this study, we prepared a methoxy poly(ethylene glycol)‐b‐poly(ε‐caprolactone) diblock copolymer (MPC) with varying hydrophobic poly(ε‐caprolactone) (PCL) lengths and an MPC featuring a zwitterionic sulfobetaine (MPC‐ZW) at the chain end of the PCL segment. The terminal zwitterionic sulfobetaine was stoichiometrically modified to the terminal MPC diblock copolymer. The introduction of the zwitterionic end group lowered the crystallization enthalpies of the PCL block segments and increased the solubility of the diblock copolymer. The MPC and MPC‐ZW copolymers thus obtained formed translucent emulsions at room temperature when prepared as 20 wt %. When the temperature was increased above room temperature, MPC and MPC‐ZW exhibited a sol‐to‐gel phase transition. The phase transition and the gelation time of MPC and MPC‐ZW were affected by the length of the hydrophobic segments and the zwitterionic end group. Furthermore, introducing a zwitterionic end group into the PCL segment altered the onset temperature of gelation. Thus, we conclude that zwitterionic end groups introduced into PCL segments of distinct lengths could serve as key determinants in the thermogelling behavior of copolymers. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 2185–2191     

Effect of the directionality of the ester group on the formation of hairpins in polyesters containing naphthalene and a flexible spacer

Steady-state fluorescence measurements and molecular dynamics simulations have been used to study the intramolecular formation of excimers in five model compounds for polyesters containing naphthalene groups separated by flexible spacers. The model compounds are derived from 2-hydroxynaphthalene and HOOC (CH₂)_n COOH, n = 2–6. The ratio of the intensity of excimer and monomer emissions, I_D/I_M, is nearly independent of the viscosity of the medium, η, over the range covered in dilute solution. Although I_D/I_M is always very small, it shows an odd–even effect for the first four members of the series, with maxima when n is odd. Molecular dynamics simulations provide an explanation for the small values of I_D/I_M, their weak dependence on η, and the trend of I_D/I_M with n. The results for the present series of model compounds are compared with previous work, which reported larger values of I_D/I_M, and a stronger dependence of I_D/I_M on η, for bichromophoric compounds derived from 2-naphthoic acid and aliphatic glycols, where the direction of the ester groups is reversed. The origin of the difference in the behavior of I_D/I_M in the two series is identified. © 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 35: 1127–1133, 1997     

Anionic ring-opening polymerization of silacyclobutane derivatives

Anionic polymerizations of 1,1-dimethylsilacyclobutane, 1,1-diethylsilacyclobutane and 1-methyl-1-phenylsilacyclobutane were investigated. Addition of 5 mol % of butyllithium to a solution of 1,1-dimethylsilacyclobutane in THF-hexane (1 : 1) at −48°C provided poly(1,1-dimethylsilabutane) in 99% yield. M_n and M_w/M_n of the obtained polymer were 2400 and 1.10. This polymerization proceeded with a living nature. M_n increased in proportion as the yield of polymer increased. Addition of the second fresh feed of the monomer to the reaction mixture restarted polymerization of the second monomer at the same rate as in the initial stage. Addition of styrene to the living poly(1,1-dimethylsilabutane) provided a poly(1,1-dimethylsilabutane-b-styrene) block copolymer. It was also found that a polymerization of 1,1-diethylsilacyclobutane in THF-hexane at −48°C showed a living nature. In contrast, a polymerization of 1-methyl-1-phenylsilacyclobutane in THF at −78°C did not show a living nature. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 3207–3216, 1997     

Fluorescence study for the electrostatic interaction and aggregation in dilute polar solution of polyelectrolytes

Fluorescence decay and quenching of pyrene labels on copolymers of 2-acrylamido-2-methylpropanesulphonic acid (AMPS) and N,N-dimethylacryl-amide (DMAA) were observed in dilute salt-free aqueous solutions as a function of the mole fraction F_AMPS of AMPS from 0 to 0.896. Monoexponential and biexponential decays were found for the samples of F_AMPS < 0.35 and samples of FAMPS > 0.35, respectively. The fast decay component is 80% and the averaged lifetime <τ> and lifetime τ₁ of the fast decay decreased with increasing F_AMPS. Quenching efficiency of Cu²⁺, CH₃NO₂, and dinitrobenzene to the pyrene label was investigated in the framework of Stern-Volmer plot. The quenching effects of Cu²⁺ included both of dynamic and static ones, the latter was due to the condensed Cu²⁺. For the neutral quenchers, the quenching rate constant k_q increased when F_AMPS < 0.449 then decreased, showing a decline of accessibility to the pyrene label. I₁/I₃ value in salt-free dilute aqueous solution and in DMSO solution decreased obviously with an increase in F_AMPS, indicating that the labeled fluorophore experienced a decrease in polarity of its microenvironment with increasing charge density of the polymer. This I₁/I₃ decrease was enhanced with increasing the polymer concentration and adding salt NaCl up to 0.75 mol/L showed no effect on the appearance of this decrease. These results were interpreted consistently with the counterion condensation concept, where condensed counterions induced the “temporal” aggregation of less-polar in the polyelectrolyte solutions surrounding the pyrene labels.     

Mixing behaviour of a conjugated molecular wire candidate and an insulating fatty acid within Langmuir–Blodgett films

The conductivity, weight loss and A.C. impedance studies were carried out to establish the influence the presence of neutral copolymer (Vinyl pyrrodlidone/Vinyl acetate copolymer) with anionic surfactant (Disodium laurethsulfosuccinate) in cyclohexane propionic acid (CHPA) on the corrosion behaviour of carbon steel. The protection efficiency (P%) of AS in the absence and presence of polymer increases with increase in AS concentration until it reaches a maximum constant value near the CMC of AS and decreases with increase in solution temperature. The protective efficiency of AS can be enhanced and its critical micelle concentration shifts to low value by adding of 0.05 g/l of polymer. The critical micelle concentration of AS in the absence and presence of polymer increases with increase in temperature. The calculated thermodynamic parameters of micellization (ΔG_mic), (ΔH_mic) and (ΔS_mic) in the presence of neutral copolymer molecules with AS show that these processes are spontaneous and exothermic in nature and indicate the association between AS and neutral copolymer molecules.