Interpolymer Complexes Research Articles

Interpolymer complexes of poly(sulfonic acid)s and poly(ethylene oxide): an unexpected association.

The formation of novel interpolymer complexes (IPCs) between poly(sulfonic acid)s and poly(ethylene oxide) (PEO) is reported. The complexes were precipitated from polymer mixtures in aqueous solution and deposited on surfaces as layer-by-layer films. Based on evidence from infrared spectroscopy, the interpolymer association in poly(sulfonic acid)/PEO IPCs is ascribed to hydrogen bonding between the sulfonic acid and the ether in PEO. This interaction is not anticipated because sulfonic acids are fully dissociated in aqueous solutions due to their strong acidity. Theoretical calculations suggest that the unexpected association of PEO and poly(sulfonic acid)s results from the formation of very strong sulfonic-acid/ether hydrogen bonds, which increase the apparent pKas of the poly(sulfonic acid)s and, therefore, decrease the net charge of these polymers. It is shown that while poly(styrene sulfonic acid) (PSSA) and Nafion form IPCs with PEO, poly(vinyl sulfonic acid) (PVSA) does not. This result is explained in terms of the hydrodrophobic nature of PSSA and Nafion, which stabilizes their IPCs, and the fact that hydrogen bonds in PSSA/PEO IPCs are predicted to be stronger than in PVSA/PEO IPCs.

Superlattice assembly by interpolymer complexation.

We present a coarse grained model for a system where nanocrystals are functionalized with a polymer that is a hydrogen bond acceptor, such as polyethylene glycol (PEG), and are dispersed in a solution with a polymer whose monomers consist of a hydrogen bond donor, such as polyacrylic acid (PAA) at low pH (interpolymer complexation). We determine the minimum concentration of the polymer donor to induce aggregation and the structure and dynamics of the induced (fcc) superlattice. Our results are compared to previous and new experiments.

Interpolymer Complexation as a Strategy for Nanoparticle Assembly and Crystallization

Controlled self-assembly of nanoparticles into ordered structures is a major step to fabricating nanotechnology-based devices. Here, we report on the self-assembly of high quality superlattices of nanoparticles in aqueous suspensions induced via interpolymer complexation. Using small-angle X-ray scattering, we demonstrate that the NPs crystallize into superlattices of face-centered-cubic symmetry, initially driven by hydrogen bonding and subsequently by van der Waals forces between the complexed coronas of hydrogen-bonded polymers. We show that the lattice constant and crystal quality can be tuned by polymer concentration, suspension pH, and the length of polymer chains. Interpolymer complexation to assemble nanoparticles is scalable, inexpensive, versatile, and general.

Structural Organization of Interpolymer Complexes Formed by Poly(N-vinylamides) and Poly(methacrylic acid) Chains Regularly Grafted to Polyimide in Aqueous Solutions

The formation and structural organization of interpolymer complexes formed by poly(methacrylic acid) chains regularly grafted to polyimide (molecular brushes) and macromolecules of poly(N-vinylamides) with different molecular masses are studied by polarized luminescence. The luminescent label of the anthracene structure is covalently bound to poly(methacrylic acid) chains in a brush. It is shown that in aqueous solutions the complexes under study are stabilized by hydrogen bonds formed between proton donor and proton acceptor groups of interacting chains. The formation of these complexes depends not only on the nature of poly(N-vinylamide) but also especially on its molecular mass. An increase in the molecular mass of polyamide is followed by the formation of a more compact less hydrated structure, as proved by an increase in the time of nanosecond relaxation and enhanced binding of the diphilic organic ion. The hindrance of poly(methacrylic acid) grafted chains complexed with polyvinylamide is lower than that of corresponding linear chains. This can be explained by a higher imperfection of the formed double-stranded structures. The ionization of carboxyl groups leads to the dissociation of complexes. The pH range corresponding to the highest degree of binding of acridine orange by poly(methacrylic acid) grafted chains is broader than that corresponding to the highest degree of dye binding by the linear polyacid.

Intra- and Interpolyelectrolyte Complexes of Polyampholytes.

At present, a large amount of research from experimental and theoretical points of view has been done on interpolyelectrolyte complexes formed by electrostatic attractive forces and/or interpolymer complexes stabilized by hydrogen bonds. By contrast, relatively less attention has been given to polymer–polymer complex formation with synthetic polyampholytes (PA). In this review the complexation of polyampholytes with polyelectrolytes (PE) is considered from theoretical and application points of view. Formation of intra- and interpolyelectrolyte complexes of random, regular, block, dendritic polyampholytes are outlined. A separate subsection is devoted to amphoteric behavior of interpolyelectrolyte complexes. The realization of the so-called “isoelectric effect” for interpolyelectrolyte complexes of water-soluble polyampholytes, amphoteric hydrogels and cryogels with respect to surfactants, dye molecules, polyelectrolytes and proteins is demonstrated.

Flexible electro-responsive in-situ polymer acid doped polyaniline membranes for permeation enhancement and membrane fouling removal

This study investigates the performance of a new electrically tuneable polyaniline (PANI) membrane, and shows that this synthesis method has the potential to address key challenges of small-acid doped PANI membranes, including: acid dopants leaching out during filtration and low mechanical strength. The novel in-situ polymerisation used poly (2-acrylamido-2-methyl-1-propanesulfonic acid) (PAMPSA), as polymer acid template leads to the formation of inter-polymer complexes of PANI and polymer acid. The developed membranes were comprehensibly evaluated through visual, chemical, mechanical and filtration studies and compared to small-acid doped membranes (PANI-HCl membranes). The PANI-PAMPSA membranes were smooth, acid leach resistant, had higher tensile strength and showed conductivity three magnitudes higher compared to PANI membrane with post cast doping. The developed membrane showed in-filtration performance stability, electrical tuneability (in-situ control of flux and rejection) and fouling removal characteristics under applied electrical potential. Data obtained by SEM, IR spectroscopy, electrical analysis and cross-flow filtration confirm these results. The overall results showed that the proposed membrane fabrication procedure resulted in a significant improvement in performance across a range of critical parameters, including conductivity, stability, flexibility, permeance and fouling removal with additional advantage of being electrically tuneable.

Physicochemical and Technical Studies of an Interpolymer Complex of Polymethyacrylic Acid and Polyethylene Glycol as the Base for Creating Matrix Systems

The physicochemical and technological properties of an interpolymer complex of polymethyacrylic acid and polyethylene glycol, known under its commercial name “Polymer Carrier Composition” (FGUP Science Research Institute of Polymers, Russia), were studied. This polymer is an excipient substance used in the technology of solid dosage forms as a matrix former and as a film-forming agent for making long-acting and slow-release formulations. With the aim of widening the potential uses of the polymer carrier composition, the solubility of the polymer in aqueous solutions and organic solvents was studied, along with the technological and surfactant properties of the polymer; the critical gel-forming concentration was also determined. Experimental samples of tablets and oral gels of model substances with similar physicochemical properties were prepared, based on different concentrations of the Polymer Carrier Composition, and the technological, rheological, and biopharmaceutical properties of these were studied. The potential for using the polymer in both hard and soft dosage forms to obtain prolonged-release medicinal formulations is demonstrated.

Highly Stretchable, Self-Healable Elastomers from Hydrogen-Bonded Interpolymer Complex (HIPC) and Their Use as Sensitive, Stable Electric Skin.

There is a growing interest in developing stretchable strain sensors to quantify the large mechanical deformation and strain associated with the activities for a wide range of species. Herein, we constructed elastomeric, healable hydrogen-bonded interpolymer complex (HIPC) rubberlike film by complexation of hydrogen-bond (H-bond)-donating poly(acrylic acid) (PAA) and H-bond-accepting poly(ethylene oxide) (PEO) (or poly(ethylene oxide)–poly(propylene oxide)–poly(ethylene oxide) (F108)). All HIPC elastomers prepared from varied PAA/PEO (or PAA/F108) ratios are healable elastomers with high extensibility (with the highest strain of 1400%). Recovery of all films can automatically occur or be accelerated by externally added water droplet. The stress- and strain healing efficiencies (ησ and ηε) of the water-assisting healed PAA/F108 blends are as high as 99%. Furthermore, stretchable and healable conductor films were fabricated from silver nanowire-printed (Ag-p) and the single-walled carbon nanotube-blended (SW-b) conductor films, respectively. The healable Ag-p conductor film is an ultrasensitive strain sensor, exhibiting large electric resistance variation when stretched. In contrast, the healable SW-b film is an ultrastable strain sensor with reversible resistance strain response over 200 stretching release cycles within a high strain range of 500%. Therefore, this study provides a new and flexible HIPC strategy for the fabrication of stretchable, ultrasensitive, and stable self-healing electrode materials.

Effect of organic and inorganic salt environment on the complex coacervation of in situ formed protein nanoparticles and DNA

Complex coacervation was noticed between in situ formed protein (a primarily hydrophobic Zein protein with pI = 6.2) nanoparticles (size 80–120 nm) and ds-DNA (a high charge density polyanion), in the ionic liquid (IL) solutions of 1-ethyl-3-methyl imidazolium chloride [C2mim][Cl], and 1-octyl-3-methyl imidazolium chloride [C8mim][Cl], in the studied ionic strength range of I = 10−4 to 6 × 10−1 M, which was extended to strong monovalent 1:1 electrolyte (NaCl) to explore the commonality between the organic and inorganic salt (ionic) environment on coacervation. The salt dependent coacervation profile was monitored from the measured turbidity of the interacting solution, and zeta potential, (ζ) and apparent hydrodynamic radius (Rh) of interpolymer complexes, which depicted the following three discernible interaction regimes common to all the salts: (i) Region-I: I = 0.0001–0.01 M, primary binding, (ii) Region-II, I = 0.01–0.1 M, secondary binding, and (iii) Region-III, I = 0.1–0.6 M, saturation binding. The free-energy and the network density calculations favored preferential coacervation in [C2mim][Cl] samples. Nonetheless, commonality in the overall ionic strength dependent coacervation profiles could still be observed.

Investigation of the magnetic field effect upon interpolymeric complexes formation based on bovine serum albumin and poly(aspartic acid)

The study presents a novel strategy for obtaining highly ordered interpolymeric complexes based on a protein, bovine serum albumin and a synthetic polymer, poly(aspartic acid). In this approach, experimental tests were carried out in the presence of a magnetic field of different intensities, namely 0.11 T and 0.3 T produced by permanent magnets. The influence of the magnetic force on the complexation process and the resulted self-assembled structures were studied by means of FTIR spectroscopy, X-ray diffraction, DLS, SEM microscopy and in vitro assay. The changes in the FTIR spectra acquired after 24 h of exposure were connected with conformational changes in the secondary structure and increased interactions between polymers, particularly when a higher intensity field was used. Due to a large anisotropy of magnetic susceptibility characteristic to both proteins and polypeptides, the magnetic field generated ordered assemblies consisting in globular structures of nanometric dimensions. This assembly strategy using magnets, along with remote manipulation capability can provide a versatile, contact-free, and inexpensive tool to create new, complex materials with tailorable characteristics.

Preparation of multifunctional poly(acrylic acid)-poly(ethylene oxide) nanogels from their interpolymer complexes by radiation-induced intramolecular crosslinking

Poly(acrylic acid)-poly(ethylene oxide) (PAA-PEO) interpolymer complexes (IPC)s were prepared with equimolar stoichiometric ratio of repeating units and converted to crosslinked nanogels via γ-ray irradiation of aqueous acetone solutions. The effect of acetone concentration on the coil size of nanogels was investigated by dynamic light scattering (DLS). pH and temperature effects on the size and surface charge of nanogels were studied by using DLS. Zeta potentials of the PAA-PEO nanogels were between − 5.31 mV (pH = 2) and − 45.00 mV (pH = 11) depending on dissociation of PAA. Atomic force microscopy (AFM) and transmission electron microscopy (TEM) pictures showed that dry PAA-PEO nanogels are spherical with diameters of ~ 100 and ~ 240 nm in the swollen state as determined by DLS. PAA-PEO nanogels synthesized in 25% (v/v) acetone/water mixture exhibited size stability over a period of 2 months. This simple method of preparing nanogels from polymer pairs avoids tiresome synthesis of corresponding block copolymers as precursors of functional nanogels.

Structure of Hybrid Interpolymeric Complexes of Zinc Halides with Polyvinyl Alcohol

Structure of Hybrid Interpolymeric Complexes of Zinc Halides with Polyvinyl Alcohol

Supramolecular poly(acrylic acid)/F127 hydrogel with hydration-controlled nitric oxide release for enhancing wound healing

Topical nitric oxide (NO) delivery has been shown to accelerate wound healing. However, delivering NO to wounds at appropriate rates and doses requires new biomaterial-based strategies. Here, we describe the development of supramolecular interpolymer complex hydrogels comprising PEO-PPO-PEO (F127) micelles embedded in a poly(acrylic acid) (PAA) matrix, with S-nitrosoglutathione (GSNO) molecules dissolved in the hydrophilic domain. We show that PAA:F127/GSNO hydrogels start releasing NO upon hydration at rates controlled by their rates of water absorption. SAXS measurements indicate that the supramolecular structure of the hydrogels retains long-range order domains of F127 micelles. The PAA/F1227 hydrogels displayed dense morphologies and reduced rates of hydration. The NO release rates remain constant over the first 200 min, are directly correlated with the hydration rates of the PAA:F127/GSNO hydrogels, and can be modulated in the range of 40 nmol/g h to 1.5 μmol/g h by changing the PAA:F127 mass ratio. Long-term NO-release profiles over 5 days are governed by the first-order exponential decay of GSNO, with half-lives in the range of 0.5–3.4 days. A preliminary in vivo study on full-thickness excisional wounds in mice showed that topical NO release from the PAA:F127/GSNO hydrogels is triggered by exudate absorption and leads to increased angiogenesis and collagen fiber organization, as well as TGF-β, IGF-1, SDF-1, and IL-10 gene expressions in the cicatricial tissue. In summary, these results suggest that hydration-controlled NO release from topical PAA:F127/GSNO hydrogels is a potential strategy for enhancing wound healing. Statement of SignificanceThe topical delivery of nitric oxide (NO) to wounds may provide significant beneficial results and represent a promising strategy to treat chronic wounds. However, wound dressings capable of releasing NO after application and allowing the modulation of NO release rates, demand new platforms. Here, we describe a novel strategy to overcome these challenges, based on the use of supramolecular poly(acrylic acid) (PAA):F127 hydrogels charged with the NO donor S-nitrosoglutathione (GSNO) from whereby the NO release can be triggered by exudate absorption and delivered to the wound at rates controlled by the PAA:F127 mass ratio. Preliminary in vivo results offer a proof of concept for this strategy by demonstrating increased angiogenesis; collagen fibers organization; and TGF-β, IGF-1, SDF-1, and IL-10 gene expressions in the cicatricial tissue after topical treatment with a PAA:F127/GSNO hydrogel.

Pyrene-Terminated, Amphiphilic Polypeptide and Its Hydrogen-Bonded Interpolymer Complex as Delivery Systems of Doxorubicin.

The intensity ratio between the first (373 nm) and the third (383 nm) vibronic peaks [I1/I3, as the pyrene (Py) scale] of fluorescent Py was used to monitor the critical concentration, drug-loading, and -releasing behaviors of a Py-terminated, amphiphilic polypeptide PPM and its hydrogen-bonded interpolymer complex (HIPC) with poly(acrylic acid) (PAA). Primarily, an amphiphilic PPM with a hydrophobic Py terminal and hydrophilic methoxy-bis(ethylene oxide) pendant groups was synthesized through multiple preparative steps, and the resultant PPM was thoroughly mixed with PAA through a preferable hydrogen bond (H bond) interaction to form HIPC. The emission study suggested that the I1/I3 ratio and the quantum yield (ΦF) are effective in determining the critical concentrations of the aqueous PPM and PPM/PAA solutions. Moreover, the I1/I3 ratio and ΦF were found to be convenient measures for determining the amounts of doxorubicin drugs loaded by and released from the aqueous PPM and PPM/PAA solutions.

Surface characterization of nanoparticles using near-field light scattering.

The effect of nanoparticle surface coating characteristics on colloidal stability in solution is a critical parameter in understanding the potential applications of nanoparticles, especially in biomedicine. Here we explored the modification of the surface of poly(ethylene glycol)-coated superparamagnetic iron oxide nanoparticles (PEG-SPIOs) with the synthetic pseudotannin polygallol via interpolymer complexation (IPC). Changes in particle size and zeta potential were indirectly assessed via differences between PEG-SPIOs and IPC-SPIOs in particle velocity and scattering intensity using near-field light scattering. The local scattering intensity is correlated with the distance between the particle and waveguide, which is affected by the size of the particle (coating thickness) as well as the interactions between the particle and waveguide (related to the zeta potential of the coating). Therefore, we report here the use of near-field light scattering using nanophotonic force microscopy (using a NanoTweezerTM instrument, Halo Labs) to determine the changes that occurred in hydrated particle characteristics, which is accompanied by an analytical model. Furthermore, we found that altering the salt concentration of the suspension solution affected the velocity of particles due to the change of dielectric constant and viscosity of the solution. These findings suggest that this technique is suitable for studying particle surface changes and perhaps can be used to dynamically study reaction kinetics at the particle surface.

Interpolymeric Complexes Formed Between Whey Proteins and Biopolymers: Delivery Systems of Bioactive Ingredients.

Whey proteins are obtained from dairy industry waste. Studies involving the analysis of the bioactive compounds in whey show health benefits, as it is an excellent source of indispensable amino acids. Milk whey contains principally β-lactoglobulin, α-lactoglobulin, bovine serum albumin, and lactoferrin, proteins with innumerable functional and technological properties. One application of these proteins in food is the formation of interpolymer complexes, along with other proteins or anionic polysaccharides. The formation of complexes occurs mainly through electrostatic interactions between a negatively charged biopolymer and a positively charged biopolymer. This formation is influenced by factors such as pH, ionic strength, and biopolymer ratio. Because they do not use high temperatures and chemical reagents and have additional nutritional and functional value, these complexes have been used as encapsulating agents for bioactive ingredients. Recent studies on their training and applications are addressed in this review to boost new research and applications in the food industry, thus increasing opportunities for utilizing whey proteins.

Zipper-like magnetic molecularly imprinted microspheres for on/off-switchable recognition and extraction of 17β-estradiol from food samples

Zipper-like on/off-switchable and magnetic molecularly imprinted microspheres (SM-MIMs) were constructed using acrylamide (AAm) and 2-acrylamide-2-methyl propanesulfonic acid (AMPS) as functional monomers for 17β-estradiol (17β-E2) recognition and extraction. The imprinted polymer interactions between poly(AAm) (PAAm) and poly(AMPS) (PAMPS) with on/off-switchable property to temperature, exhibited dissociation at relatively higher temperatures (such as 30 °C) and helped 17β-E2 enter into imprinted sites, leading to higher binding capability. Conversely, the interpolymer complexes between PAAm and PAMPS formed and blocked 17β-E2 access to imprinted sites at lower temperature (such as 20 °C). SM-MIMs were used as dispersive solid phase extraction (SPE) adsorbent with HPLC for 17β-E2 pretreatment and detection in food samples, and low limit detection (2.52 µg L−1) and quantification (10.76 µg L−1) with higher recovery were obtained. Therefore, SM-MIMs may be a promising adsorbent for 17β-E2 pretreatment in food samples owing to its advantages of on/off-switchable recognition, eco-friendly elution, and efficient separation.

Effect of molecular weight of poly(acrylic acid) on the interaction of oppositely charged ionic surfactant–polyelectrolyte mixtures

Abstract The isothermal titration calorimetry was applied to investigate the effect of molecular weight (MW) of poly(acrylic acid) (PAA) on the interaction of tetradecyltrimethyl ammonium bromide (C14TAB) with PAA in the bulk phase. The initial formation of PAA/C14TAB complexes was driven by electrostatic interactions between the cationic head groups of C14TAB and the oppositely charged PAA chains, resulting in enhanced hydrophobicity of the complexes. The further addition of C14TAB would induce either complex-C14TAB interaction or complex–complex interaction due to hydrophobic effect. Increasing the MW of PAA would enhance the tendency of complex–complex interaction to form aggregation and even precipitation. For PAA MW ≥ 130,000, significant precipitation of interpolymer complexes was consistently observed and all the obtained critical micelle concentration, phase separation concentration, heat of complexation, and heat of micellization were independent of MW. For PAA MW of 25,000, the complexes formed visible millimetric aggregates at phase separation concentration. With further addition of C14TAB, these aggregates gradually dissolved, and the solution became clear again. For PAA at an MW of ≤5000, turbidity was observed in a wide range of concentrations, but no macroscopic precipitation was observed and the solutions were always homogeneous.

Fast NMR Screening of Macromolecular Complexes by a Paramagnetic Spin Relaxation Filter.

The paramagnetic spin relaxation filter is described for the rapid NMR screening of intermolecular interactions between ligands and macromolecular anionic receptors with large transverse relaxation enhancements (R2p). The addition of micromolar concentrations of Gd3+ to the mixture produces the immediate broadening/suppression of the NMR signals of interacting species while leaving unaffected those of noncompetitive binders (one-dimensional and two-dimensional experiments). The method is highly sensitive, unveiling interactions that are too weak to generate changes in chemical shifts or relaxation times. It is operationally very simple and hence, it is amenable to ready implementation by nonspecialists. Examples of application such as detecting the formation of interpolymer complexes, cyclodextrin host–guest interactions, and the screening of DNA ligands are included that demonstrate the reliability and broad applicability of the method.

Formulation of Carbopol®/Poly(2-ethyl-2-oxazoline)s Mucoadhesive Tablets for Buccal Delivery of Hydrocortisone.

Poly(2-ethyl-2-oxazoline) has become an excellent alternative to the use of poly(ethylene glycol) in pharmaceutical formulations due to its valuable physicochemical and biological properties. This work presents a formulation of poorly-water soluble drug, hydrocortisone, using interpolymer complexes and physical blends of poly(2-ethyl-2-oxazoline)s and two Carbopols® (Carbopol 974 and Carbopol 971) for oromucosal administration. The swelling, hydrocortisone release and mucoadhesive properties of a series of tablet formulations obtained by combination of different Carbopols with poly(2-ethyl-2-oxazoline)s of different molecular weights have been evaluated in vitro.