Intermolecular interaction in aqueous solution of binary blends of poly(acrylamide) and poly(ethylene glycol) (original) (raw)
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Journal of Applied Polymer Science, 2007
Differential scanning calorimetry (DSC) of triple blends of high molecular weight poly(N-vinyl pyrrolidone) (PVP) with oligomeric poly(ethylene glycol) (PEG) of molecular weight 400 g/mol and copolymer of methacrylic acid with ethylacrylate (PMAA-co-EA) demonstrates partial miscibility of polymer components, which is due to formation of interpolymer hydrogen bonds (reversible crosslinking). Because both PVP and PMAA-co-EA are amorphous polymers and PEG exhibits crystalline phase, the DSC examination is informative on the phase state of PEG in the triple blends and reveals a strong competition between PEG and PMAA-co-EA for interaction with PVP. The hydrogen bonding in the triple PVP–PEG–PMAA-co-EA blends has been established with FTIR Spectroscopy. To evaluate the relative strengths of hydrogen bonded complexes in PVP–PEG–PMAA-co-EA blends, quantum-chemical calculations were performed. According to this analysis, the energy of H-bonding has been found to diminish in the order: PVP–PMAA-co-EA–PEG(OH) > PVP–(OH)PEG(OH)–PVP > PVP–H2O > PVP–PEG(OH) > PMAA-co-EA–PEG(O) > PVP–PMAA-co-EA > PMAA-co-EA–PEG(OH). Thus, most stable complexes are the triple PVP–PMAA-co-EA–PEG(OH) complex and the complex wherein comparatively short PEG chains form simultaneously two hydrogen bonds to PVP carbonyl groups through both terminal OH-groups, acting as H-bonding crosslinks between longer PVP backbones. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2011
The purpose of this study is to investigate the temperature influence on the complex formation in aqueous solutions of mixtures between a nonionic polymer, i.e., poly(ethylene glycol) (PEG), and a polyelectrolyte type polymer, namely poly(aspartic acid) (PAS). The PAS/PEG/water colloidal systems were studied as a function of the PEG chain length at different temperatures: 22 • C, 26 • C, 30.7 • C and 37 • C, temperatures corresponding to the storage and use conditions of the systems. The changes of the electrokinetic and rheological properties were revealed and correlated with the information given by Fourier Transform Infra-Red Spectroscopy (FTIR) studies in order to underline the interpenetration process between PAS and PEG macromolecular chains. The study evidences the unfavorable effect of the temperature upon interpolymeric complex formation. Both homopolymers are biocompatible and their resulting interpolymeric complex can be regarded as a network with potential bioapplications.
Polymer, 2000
The solution properties and the phase behaviour of random copolymers of N-isopropylacrylamide (NIPAM) with acrylic acid (AA) have been investigated. The mole fraction of NIPAM in these copolymers (x) varies from 0 to 0.29. At pH 3.00, i.e. when the AA groups are in the undissociated form, the intrinsic viscosity decreases substantially as x increases. This chain shrinkage is attributed to the formation of intrachain hydrogen bonds between the two complementary groups, AA and NIPAM. The weakening of the hydrophilic character and the appearance of hydrophobic properties with increasing x is further supported by fluorescence probing studies and potentiometric measurements of the aqueous copolymer solutions. Moreover, the phase behaviour of these copolymers in salt solution changes dramatically with x. The copolymer with x 0:10 presents, like the homopolymer poly(acrylic acid), an Upper Critical Solution Temperature (UCST) behaviour. On the contrary, the copolymer with x 0:29 presents, similar to the homopolymer poly(N-isopropylacrylamide), a Lower Critical Solution Temperature (LCST) behaviour. Finally, the copolymer with the intermediate NIPAM content, x 0:17; presents both an UCST and an LCST behaviour. ᭧
Langmuir, 2013
Polyethylene glycol (PEG) at various molecular weights (MWs) has been regarded as a wonder molecule in biomedical applications. For instance, PEG serves as a unique moiety for pegylation of "biobetter" drug development, PEG provides controlled-release and preserved activity of biologics, and PEG modified surface works as an antibiofouling surface. The primary characteristics of PEG molecules used in relevant applications have been attributed mainly to the hydration behavior in aqueous solutions. However, the effects on the solvation of solutes in solution caused by presenting PEG molecules as a cosolvent, as well as the thermodynamics aspect of the hydration behavior of PEG in solution, have not been well documented. The solvation behavior of solutes, such as protein, with PEG as a cosolvent, indicates the success of PEG applications, such as biofouling and controlled release. In this investigation, we examined the effects of a buffer solution containing PEG molecules on the solution behavior of solute and the interactions between solid surfaces with solutes. We adapted the study by selecting a lysozyme as a solute in a buffer solution with either ammonium sulfate (kosmotrope) or sodium chloride (chaotrope) and anionic resin (SP-Sepharose) as solid surfaces. The experiments primarily involved binding equilibrium measurements and thermodynamics analysis. The results revealed that, in both saline buffers, adding PEG increases the binding affinity between the lysozyme and the resin, similar to kosmotropic salt in the examined salt concentrations. The thermodynamics analyses involving microcalorimetric measurements show that the bindings are mainly driven by enthalpy, indicating that electrostatic interaction was the primary binding force under these experimental conditions. The variations of the enthalpy and entropy of the binding thermodynamics when adding PEG to different salt types in the buffer solution showed opposite behavior, and the results support the concept of kosmotrope-like behavior of PEG. The equilibrium and thermodynamics data demonstrate that PEG has a kosmotrope-like hydration behavior, and the extent of kosmotrope-like behavior depends on the molecular weight of PEG with the outcomes of various molecular weights of PEG being added to the binding solution. The results of this study provide essential knowledge for PEG as an additive (or cosolvent) in various research applications.
Letters in Applied NanoBioScience
The density and speed of sound for polyethylene glycols (PEG-200 and PEG-600) in an aqueous solution of D-Mannitol have been measured by Anton Paar DSA 5000M at different temperatures and concentrations. Experimentally obtained data of density and speed of sound are employed to calculate various theoretical parameters such as intermolecular free length, acoustic impedance, adiabatic compressibility, Wada's constant, Rao's Constant, and Vander Waal's constant, which gave the better insight into molecular interactions between the polyethylene glycols and D-mannitol solutions.
Polymer, 2008
Densities of the polymer and solvent components in gels made of poly[N-(1,3-dioxolan-2-ylmethyl)-N-methylacrylamide (DIOMMA)] networks and water, methanol or ethanol were determined from 5°C to near bp of the respective solvents. From the densities, we have evaluated the following quantities at various temperatures (T): (1) the volume of gels [V sp (gel)] occupied by one single polymeric residue and its associated solvent molecules; (2) mass of solvent in gels per one polymeric residue; (3) the ratio of mass of polymer or solvent vs mass of gels; and (4) the number of solvent molecules per one polymeric residue (N sp). The results in V sp (gel)(T) revealed the following: (A) V sp (gel) in the hydrogel decreased with increasing T up to 55°C. This is essentially caused by a loss of water from the gel system. The increase in V sp (gel) beyond 55°C is brought about by conformational changes in the polymer together with a further inclusion of solvents into gels. (B) Alcohol environments gave the thermally reversed trend in V sp (gel)(T) against the hydrogel. (C) Several changes in the gradient of the plot of V sp (gel) vs T for the gel made of ethanol indicated some conformational changes in the polymer at specific temperatures. These temperatures exactly matched with changes in spin-lattice relaxation times for the OH proton of ethanol that is present in gels. Altogether, the above differences in their thermal behaviors of various gels were elucidated in terms of strengths and modes of the intermolecular polymer-polymer, polymer-solvent, and solvent-solvent interactions that are modulated by thermal motions of molecules.
Salt effects on solvent features of coexisting phases in aqueous polymer/polymer two-phase systems
Journal of Chromatography A, 2012
The solvatochromic parameters characterizing the solvent dipolarity/polarizability (*), solvent hydrogen-bond donor acidity (˛), and solvent hydrogen-bond acceptor basicity (ˇ) of aqueous media were measured in the coexisting phases of aqueous Dextran-Ficoll, Dextran-Ucon, Dextran-PEG, PEG-Ucon, Ficoll-Ucon, and Ficoll-PEG two-phase systems (ATPS). Ionic composition of each ATPS included 0.15 M KCl, 0.15 M KBr, 0.15 M NaBr, 0.1 M Na 2 SO 4 , and 0.1 M Li 2 SO 4 in 0.01 M sodium phosphate buffer (NaPB), pH 7.4; and 0.01 M and 0.11 M sodium phosphate buffer, pH 7.4. Partition ratios of sodium salts of dinitrophenylated (DNP) amino acids with aliphatic side-chains (glycine, alanine, norvaline, norleucine, and ˛-amino-n-caprylic acid) were measured in all ATPSs, and the results were evaluated in terms of the differences between the relative hydrophobicity (parameter E) and the electrostatic properties (parameter C) of the aqueous media of the coexisting phases. It was established that parameter E is described by a linear combination of the differences between the solvent dipolarity/polarizability (*) and between the solvent hydrogen-bond acidity (˛) of the media in the coexisting phases. Parameter C depends on the phase forming polymer pair and is shown to be described by a linear combination of three parameters: the differences between the solvent hydrogen-bond acidity (˛) and between the solvent hydrogen-bond basicity (ˇ) of the media in the coexisting phases, and a measure of the effect of a given salt additive on the hydrogen bonds in water. This effect was represented by a parameter (K b−l), characterizing the equilibrium between populations of hydrogen bonds with a bent hydrogen bond conformation and with linear hydrogen bond conformation affected by a given salt additive.
European polymer journal, 2007
A thermodynamic approach based on both the classical Flory-Huggins (FH) formalism and the association equilibria (AE) theory has been developed to study the solubility properties of a system formed by a proton-donor solvent (A), a proton-acceptor solvent (B) and a proton-acceptor polymer (C). The miscibility of this ternary system is attained by competitive specific interactions via hydrogen-bonding established between the hydroxyl and carbonyl interacting groups of either solvent-solvent (AB) or solvent-polymer (AC) system components. The binary AB and AC specific interactions and their dependence with the system composition as well as with the extent of the association equilibrium have been quantified by means of two new parameters, Dg AB and Dg AC. These excess functions have appeared to be equivalent to the combinatorial or entropic term of the Gibbs free energy of the complex formation process, which accounts for the entropy of mixing plus the intermolecular specific interactions. The theoretical predictions have reasonablely agreed with experimental data on preferential solvation of two systems taken from literature: methanol(A)/1,4-dioxane(B)/poly(alkyl methacrylate)(C) and n-alcohol(A)/heptan-3-one(B)/poly(vinyl pyrrolidone)(C).