Copolymers Of Vinylpyrrolidone Research Articles

Optimisation of Pharmaceutical Cocrystal Dissolution Performance through a Synergistic Precipitation Inhibition

ObjectivesPolymeric excipients play an important role in a cocrystal formulation to act as precipitation inhibitors to maximize the potential. Otherwise, a stable form of the parent drug will be recrystallized on the dissolving cocrystal surface and/or in the bulk solution during the cocrystal dissolution process, negating the solubility advantage. The objectives of this work were to investigate the potential of using combined polymers to maximise the dissolution performance of surface precipitation pharmaceutical cocrystals.MethodsThe dissolution performance of a highly soluble flufenamic acid and nicotinamide (FFA-NIC) cocrystal has been systematically studied with predissolved or powder mixed with a single polymer, including a surface precipitation inhibitor [i.e., copolymer of vinylpyrrolidone (60%) /vinyl acetate (40%) (PVP-VA)] and two bulk precipitation inhibitors [i.e., polyethylene glycol (PEG) and Soluplus (SLP)], or binary polymers combinations.ResultsA single polymer of PVP-VA prevented the FFA surface precipitation for an enhanced dissolution performance of FFA-NIC cocrystal. Unfortunately, it cannot sustain the supersaturated FFA concentration in the bulk solution. A combination of two polymers of PVP-VA and SLP has shown a synergistic inhibition effect to enhance the dissolution advantage of FFA-NIC cocrystal.ConclusionsThe dissolution of a cocrystal with surface precipitation of the parent drug can be described as: i) the cocrystal surface contacting the dissolution medium; ii) the cocrystal surface dissolving; iii) the parent drug precipitation on the dissolving surface; and iv) the parent drug particles redissolving. A combination of two types of polymers can be used to maximise the cocrystal performance in solution.Graphical

Tuning the growth morphology of gypsum crystals by polymers

True control over the morphology of gypsum crystals formed via homogeneous precipitation from solution has rarely been reported in the literature. In this work, we have tested a large number of dissolved additives (polymers as well as small molecules) with respect to their ability to alter the typical microscopic appearance of precipitated gypsum powders, which is usually characterized by a mixture of single-crystalline needles and twinned plates. Among the many additives studied, a copolymer of vinylpyrrolidone and acrylic acid (PVP-co-PAA) was identified as powerful growth modifier for gypsum already at low concentrations. In both slow titration and rapid mixing experiments, unconventional blocky crystals with tilted stacking edges as well as pseudo-hexagonal plates could be synthesized reproducibly with the help of the copolymer. Systematic characterization revealed the dynamic mode of action of the newly identified growth modifier, which seems to stabilize a highly reactive face of gypsum and promote the formation of macrosteps. The degree of morphological control achieved in this way is unprecedented in the case of calcium sulfate and may devise entirely new concepts for additive design in the areas of plasters and cementitious materials, gypsum wallboard production and/or scale prevention.

Antiseptic Polymer-Surfactant Complexes with Long-Lasting Activity against SARS-CoV-2.

Antiseptic polymer gel–surfactant complexes were prepared by incorporating the low-molecular-weight cationic disinfectant cetylpyridinium chloride into the oppositely charged, slightly cross-linked polymer matrices. Three types of polymers were used: copolymers of acrylamide and sodium 2-acrylamido-2-methylpropane sulfonate; copolymers of acrylamide and sodium methacrylate; copolymers of vinylpyrrolidone and sodium methacrylate. It was shown that the rate of the release of the cationic disinfectant from the oppositely charged polymer gels could be tuned in a fairly broad range by varying the concentration of the disinfectant, the degree of swelling, and degree of cross-linking of the gel and the content/type of anionic repeat units in the polymer matrix. Polymer–surfactant complexes were demonstrated to reduce SARS-CoV-2 titer by seven orders of magnitude in as little as 5 s. The complexes retained strong virucidal activity against SARS-CoV-2 for at least one week.

Synthesis and characterization of tailor‐made N‐vinylpyrrolidone copolymers and their blend membranes with polyvinyl alcohol for bioethanol dehydration by pervaporation

AbstractTailor‐made poly(N‐vinylpyrrolidone‐co‐(2‐[dimethylamino]ethyl methacrylate)) P(NVP‐co‐DMAEMA) and poly(N‐vinylpyrrolidone‐co‐N‐vinylimidazole) P(NVP‐co‐PNVIm) with defined monomer molar ratio are synthesized via free radical polymerization. The random copolymers are fully characterized and then blended with polyvinyl alcohol (PVA) to investigate their chemical and thermal properties as membrane materials. Composite membranes are further prepared from the PVA/copolymer blends on a porous support, which are evaluated in terms of separation performance for the dehydration of ethanol by pervaporation. The membranes prepared from the blends exhibit up to four times higher water permeances than pristine PVA membrane, albeit the selectivity is slightly lower. Nevertheless, the membranes from blends with a ratio of 95:5 (PVA/copolymer) show improved selectivity and higher permeance values compared to the commercial PERVAP™ 4155–80, especially the blends composed by the copolymers of coPDMAEMA60 and coPDMAEMA20. The membrane prepared from the blend containing the homopolymer coPDMAEMA100 exhibits the highest water/ethanol selectivity and shows stable separation performance throughout the whole long‐term stability test. Thus, this study demonstrated that by synthesizing tailored copolymers (rather using the commercial ones) and blending with PVA, the separation performance of membranes can be significantly improved and tuned for specific dehydration processes.

Understanding the Effects of a Polymer on the Surface Dissolution of Pharmaceutical Cocrystals Using Combined Experimental and Molecular Dynamics Simulation Approaches.

The molecular interactions between the surfaces of cocrystals [i.e., flufenamic acid and theophylline (FFA-TP), flufenamic acid and nicotinamide (FFA-NIC), and carbamazepine and nicotinamide (CBZ-NIC)] and the polymers [i.e., polyethylene glycol (PEG), polyvinylpyrrolidone (PVP), and copolymer of vinylpyrrolidone (60%)/vinyl acetate (40%) (PVP-VA)] were investigated through combined experimental and molecular dynamics simulation approaches to resolve the mechanisms of cocrystal dissolution and precipitation. It was found that adsorption of the polymers on the surfaces of cocrystals might prevent the precipitation of the parent drug and alter the dissolution rate. The effect of polymers on precipitation could be determined by the cocrystal dissolution rate, the interactions of polymers with the surfaces of cocrystals, the characters of the noncovalent bonds formed between the polymers and the cocrystal surfaces, and the mobility and conformation of the polymers. The etching experiments of single cocrystals revealed that FFA-NIC and CBZ-NIC appeared as surface precipitation cocrystals while FFA-TP could lead to bulk precipitation. Both PVP and PVP-VA were good precipitation inhibitors for FFA-NIC, and they could completely inhibit the recrystallization of FFA III on the surfaces of dissolving cocrystals. In addition, as the adsorption of the polymer was slower than dissolution rate of the cocrystals, PVP and PVP-VA could only partially inhibit the recrystallization of CBZ dihydrate on the surface of CBZ-NIC. While PEG had no inhibitory effect on the surface crystallization of FFA-NIC and CBZ-NIC, due to its weak interactions with the surfaces of the cocrystals, it enhanced the dissolution performance of FFA-TP. In contrast, PVP and PVP-VA reduced the dissolution rate of FFA-TP and subsequently undermined the performance of cocrystals. Taken together, the approach of combining experimental and molecular dynamics simulation provided insights into the mechanisms of cocrystal dissolution as well as the polymers acting as inhibitory excipients for precipitation/recrystallization, making contribution to the development of novel formulations.

Characteristic Assessment of the Polymeric Films Used for Hair Gel Products in Thailand

The market of hair gel products in Thailand steadily grows with the changing trend of fashion every year. The main component of the hair gel products is the fixative polymer, which plays a role in hair styling properties including stiffness and curl retention. Properties of the hair styling product depending on hair types and climates must be suitably improved for Thai hair. In this study, 10 %w/w gel solutions of polyacrylic acid, polyquaternium-86, polyvinylpyrrolidone (PVP), acrylates copolymer, and vinylpyrrolidone (VP) copolymers were cast as polymeric thin films. The film properties such as mechanical properties, wettability, and crystallinity were characterized afterwards. As a result, the highest puncture strength of 2.2 N/mm2 was found from PVP-K90 film (500-700 μm thick). Whereas, VP/vinyl acetate (VA) copolymer film was the most flexible with 42.5% elongation. For water contact angle analysis, it was noticed that VP copolymers had the angle of ~50o indicating the moderate wettability. The x-ray patterns of raw materials, polymeric films, and humidified films were varied especially for PVP-K30. Morphologies of the Thai hair samples coated with the fixative polymers were visualized through SEM. After storing coated hair samples in the humidified atmosphere (95±2% Relative humidity), acrylates copolymer, VP/Methacrylamide/Vinyl Imidazole copolymer, and VP/VA copolymer appeared the humidity resistance suitable for Thai hair styling gel.

Nanoporous polymer networks of N − vinylpyrrolidone with dimethacrylates of various polarity. Synthesis, structure, and properties

Nanoporous polymer networks of N − vinylpyrrolidone (VP) with dimethacrylates of ethylene, 1,6 − hexanediol and triethylene glycol were obtained by three-dimensional free-radical copolymerization in bulk using branched copolymers as pores templates. The branched copolymers consisted of monomers of the same type to provide their thermodynamically compatibility and solubility in the appropriate mixtures of VP − dimethacrylate. They were synthesized by radical copolymerization in toluene under chain transfer condition and characterized by the FTIR, 1H NMR, GPC, DSC and DLS methods. After curing of the stable visually homogeneous monomer-polymer mixtures, polymer composites with optical properties differed from conventional network copolymers were obtained due to the micro- or macrophase separation. According to the gravimetry, FTIR, GPC and DSC data, the macromolecular additives were partly extracted by isopropyl alcohol as a “good” solvent. The hierarchical nanoporous structure of the obtained gels was demonstrated by the SEM and low-temperature nitrogen adsorption methods. Polymer networks crosslinked with dimethacrylates of ethylene and triethylene glycol contained mostly mesopores, while pores less than 20 nm predominated in the N − vinylpyrrolidone copolymer crosslinked with 1,6 − hexanediol dimethacrylate. It was shown that the values of the specific surface area increased by an order in comparison with conventional polymer networks and reached about 11–16 m2/g.

N‐vinylpyrrolidone copolymers decorated with silver nanoparticles for biomedical applications

New silver nanocomposites (AgNCs) based on copolymers of N‐vinylpyrrolidone with N,N‐diallyl‐N′‐acetylhydrazine, poly (VP‐DAAH), and 3‐methacryloxytetrahydrothiophenedioxide‐1,1, poly (VP‐MTT), have been developed. The reduction of silver ions into silver nanoparticles was achieved using NaBH4 as reducing agent. UV‐spectroscopy, an atomic force microscopy and scanning electron microscopy techniques were used to characterize the formation of silver nanoparticles in copolymers. The average silver particle size ranged from 12 to 13 nm, with the corresponding UV–vis absorption peak position at 400 to 410 nm. The AgNCs have exhibited significant cytotoxic activity towards rhabdomyosarcoma and melanoma line cells. The AgNC based on poly (VP‐MTT) completely inhibited bacterial growth, including both gram‐positive and gram‐negative bacteria.

Effect of vinylpyrrolidone polymers on the solubility and supersaturation of drugs; a study using the Cheqsol method

The development of methods to increase the bioavailability of drugs is of great interest, especially for those which are poorly soluble or permeable. One of the strategies to enhance the solubility (which in turn has the potential of increase bioavailability) of drugs is the use of additives in the formulation process, so that the drug can stay supersaturated in biological fluids for a period of time long enough to allow absorption. The use of polymers as pharmaceutical excipients in order to stabilize the supersaturation of drugs is common practice. In this work, the ability of different polymers of vinylpyrrolidone (K-12, K-17, K-25, K-29/32, K-90) and a copolymer of vinylpyrrolidone and vinylacetate (S-630) have been tested for their impact on the supersaturation of drugs. Sixteen drugs of different chemical nature have been selected, and analyzed using the Cheqsol method. The results of the drug alone, and of physical mixtures with the different polymers at several polymer:drug ratios have been compared in terms of supersaturation extent and duration. It has been observed that acidic compounds displayed enhanced solubility in different ways: sometimes the supersaturated state of the drug is maintained for a long time, due to the precipitation of an amorphous solid, as determined by X-ray diffraction studies; on other occasions supersaturation increases but only for a short time, compared to the drug alone, and then the drug precipitates to a crystalline form. Only a few basic drugs displayed enhanced solubility in the presence of PVP polymers, in contrast to acidic compounds.

Acidic and basic polymers for molecularly imprinted folic acid sensors—QCM studies with thin films and nanoparticles

Folic acid has been used as a template to generate molecularly imprinted polymers (MIPs), both thin films and nanoparticles. Systematic studies on binding behavior include using two different polymer systems, namely methacrylates and acrylate–vinyl pyrrolidone copolymers. Both yield sensor characteristics with lower limits of detection of 1–30 ppm with QCM (quartz crystal microbalance), whereas the non-imprinted polymers do not generate any signals. For methacrylate-based systems, switching from thin films to MIP nanoparticles increases sensitivity by a factor of 3 and selectivity toward metabolites (leucovorin and anhydroleucovorin) from broadband to specific. In contrast to this, in poly vinyl pyrrolidone based materials going from thin films to MIP nanoparticles does not increase sensitivity, but selectivity: thin films yield selectivity factors of 2–3 between folic acid and its metabolites, whereas nanoparticles do not show any response toward the latter and thus can be regarded specific. Hence, not only the heterocyclic backbone, but also the carboxylic groups of the folic acid molecule play fundamental role in detection. Vinyl pyrrolidone thus is the more suitable monomer than methacrylic acid to ensure these properties.

Microstructure and biological activity of sulfonated N-vinylpyrrolidone copolymers

This article deals with the preparation, characterization, and in vitro evaluation of new copolymers based on functionalized N-vinylpyrrolidone bearing pendant sulfonic acid groups statistically or alternately distributed in the macromolecular chains. Statistical copolymers were obtained by free radical polymerization of N-vinylpyrrolidone and sulfonated N-vinylpyrrolidone ( r VP = 1.61; r VPSulf = 0.90) in water, and alternating copolymers were synthesized by free radical polymerization of N-vinylpyrrolidone or sulfonated N-vinylpyrrolidone with methyl maleate in N,N-dimethylformamide followed by hydrolysis of the resulting copolymers. The influence of these new materials on acidic fibroblast growth factor–mediated mitogenesis of fibroblasts demonstrated that sequence distribution (copolymer microstructure) plays a key role in the biological performance of these polymers. Alternating copolymers did not present biological activity, whereas statistical copolymers inhibited acidic fibroblast growth factor activity in a sulfonated N-vinylpyrrolidone dose-dependent manner.

Calcium Carbonate Microparticles Growth Templated by an Oxadiazole-Functionalized Maleic Anhydride-co-N-vinyl-pyrrolidone Copolymer, with Enhanced pH Stability and Variable Loading Capabilities

The crystallization characteristics of CaCO3 microparticles from supersaturate aqueous solutions in the presence of a conjugate drug-copolymer has been investigated, comparative with particles prepared in similar conditions but without polymer. The polymer conjugate, P(NVP-MA-Ox), is based on poly(N-vinylpyrrolidone-co-maleic anhydride) as support and 2-amino-5-(4-methoxy-phenyl)-1,3,4-oxadiazole. The influence of the polymer/CaCO3 ratio on the microparticles' characteristics and the particles' pH stability was deeply investigated by scanning electron microscopy, X-ray diffraction, flow particle image analysis, particles charge density, and electrophoresis. The presence of P(NVP-MA-Ox) as a template in the CaCO3 crystallization process induced the particles stability increase up to the polymer isoelectric point located at pH = 3.4, irrespective of carbonate content in composite particles. The adsorption capacity of the microparticles as a function of their characteristics was tested using methylene blue. The sorption capacity of composite materials increased with the increase of polymer content in the composites, suggesting that the sorption process takes place mainly by electrostatic interactions.

Mixtures of Cationic Copolymers and Oppositely Charged Surfactants: Effect of Polymer Charge Density and Ionic Strength on the Adsorption Behavior at the Silica–Aqueous Interface

This study addresses polymer-surfactant interactions at solid-liquid interfaces and how these can be manipulated by modulating the association between ionic surfactant and oppositely charged polymer, with a particular focus on electrostatic interactions. For this purpose, the interaction of a series of cationic copolymers of vinylpyrrolidone and quaternized vinylimidazol with sodium dodecyl sulfate (SDS) at the silica-aqueous interface was followed by in situ ellipsometry. To reveal the nature of the interaction, we performed measurements for different copolyion charge densities, in the absence and presence of added salt. The path-dependence of the interaction was studied by comparing the adsorption under two different conditions, adsorption from premixed solutions and sequential addition of surfactant to the polymer solution, but the same end state. The reversibility of the adsorption process was studied by following the effect of dilution on the adsorbed layer. All copolyions adsorbed to both silica and hydrophobized silica, revealing the importance of both hydrophobic and electrostatic attractive interactions. On both types of surface, an increase in adsorbed amount was found on lowering the fraction of charged units. An increased ionic strength gave an increased adsorbed amount in all cases, but especially on hydrophobic surfaces. The adsorbed amount on silica from mixtures of the copolyions with SDS peaked at an SDS concentration corresponding closely to the concentration of cationic charges of the different polyions. Around the region of charge equivalence, there was also a phase separation in the bulk. At higher concentrations of SDS, a redissolution in the bulk, and a decrease in adsorbed amount, occurred as a result of excess SDS binding to the complexes. For the most highly charged polyions, we observed a decrease in adsorbed amount, and a shift in the adsorption maxima to lower SDS concentrations, with increasing ionic strength.

Biodegradable amphiphiles of grafted poly(lactide) onto 2‐hydroxyethyl methacrylate‐co‐N‐vinylpyrrolidone copolymers as drug carriers

AbstractThis article describes the synthesis and characterization of 2‐hydroxylethyl methacrylate‐co‐N‐vinylpyrrolidone copolymers, (HEMA‐co‐NVP), via free radical polymerization followed by grafting of poly(lactide) onto (HEMA‐co‐NVP) copolymers, via ring opening polymerization using tin octoate as a catalyst. The copolymers and the grafted copolymers (i.e., amphiphiles) were subjected to sustained release studies using salicylic acid, as a model drug. Characterization of the formed copolymers was performed using 1H‐NMR, 13C‐NMR, FTIR, TGA, DSC, and SEM techniques. Derivative of TGA thermogram was used to determine %hydrophilicity and %hydrophobicity in the grafted and ungrafted copolymers. The SEM morphology revealed porous layers with crispy structure that were most likely due to the presence of poly(lactide) chains. At lower content of poly(lactide) moiety, grafted copolymers showed non‐Fickian diffusion release rate, whereas Fickian diffusion release rate at higher content of poly(lactide) was observed. The increase of poly(lactide) content (i.e., larger %hydrophobicity) in the copolymer increased the drug‐sustainability, due to the consistent but porous amphiphilic degradable structures that allow controllable release of drug in time interval. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Analysis of Residual Vinyl Pyrrolidone Monomer in Polyvinylpyrrolidone with a Mixed Mode Separation, using a Fast Gel Permeation Chromatography Column

The technique of high throughput or fast gel permeation chromatography was used to separate and quantify residual vinyl pyrrolidone monomer present in polyvinyl pyrrolidone polymer (PVP) and in a copolymer of vinyl pyrrolidone and vinyl caprolactam [P(VP/VCL)]. The chromatography exploits both size-exclusion and adsorption modes of separation. This methodology offers a single step analysis for residual vinyl pyrrolidone monomer as compared to multi-step and time-consuming reverse-phase chromatography measurements, yielding similar results. Fast GPC and reverse-phase analyses are quantitatively compared and reported using both typical industrial and European Pharmacopeia methodologies for HPLC. The results of this study demonstrate that fast gel permeation chromatography presents a viable option to traditional reverse- phase chromatography in the quantitative analysis of residual vinyl pyrrolidone monomer.

Effects of Different Contact Lens Materials and Contact Lens–Wearing Periods on Conjunctival Cytology in Asymptomatic Contact Lens Wearers

To investigate the conjunctival cytologic changes induced by different contact lens materials and contact lens-wearing periods in asymptomatic contact lens wearers. Seventy-five patients (150 eyes) who were to wear contact lenses for the first time were evaluated in this study. Forty eyes of 20 soft hydroxyethylmethacrylate (vinyl pyrrolidone copolymer) contact lens wearers, 70 eyes of 35 soft Polymacon contact lens wearers, and 40 eyes of 20 hard gas-permeable contact lens wearers used the lenses on a daily-wear basis. Conjunctival cytologic changes were investigated by using impression cytology. Impression cytologic samples were obtained before contact lens fitting and after contact lens wear (mean evaluation time, 6.9 +/- 2.6 months; range, 4-12 months). The samples were appropriately stained and were assessed by using the Nelson grading system and for the presence of snakelike chromatin. The Kruskal-Wallis test, the Wilcoxon test, and logistic regression were used for statistical analysis. There were statistically significant differences in impression cytologic findings for all three materials before versus after contact lens wear (P=0.00, P=0.00, P=0.00, Wilcoxon test). The contact lens-wearing period produced a statistically significant effect on conjunctival cytologic changes and snakelike chromatin formation (P=0.00, P=0.00, logistic regression analysis), but the effects of different contact lens materials were insignificant (P=0.88, P=0.62). Conjunctival cytologic changes occurred in asymptomatic contact lens wearers and were related to the duration of lens wear. For this reason, asymptomatic contact lens wearers may be followed up because of conjunctival cytologic changes.

Intermolecular association of Tilan with vinylpyrrolidone copolymers

The results of physicochemical studies of promising prolonging agents for Tilan antibiotic: polyvinylpyrrolidone and vinylpyrrolidone copolymers, are reported. The optimal component ratios of the drug formulation were determined by viscometry and conductometric titration. As determined by IR spectroscopy, the components are associated mainly via intermolecular hydrogen bonds.

Estimation of Miscibility and Interaction for Cellulose Acetate and Butyrate Blends with N‐Vinylpyrrolidone Copolymers

AbstractThe miscibility of CA/P(VP‐co‐MMA) blends was examined as a function of DS of CA and the VP fraction in the copolymer composition, in an extension of the previous studies on cellulose ester blends using P(VP‐co‐VAc) as a counter component. It was observed by DSC thermal analysis that when CA of DS ≤ 2.5 and P(VP‐co‐MMA) of VP > 30 mol‐% were two blending components, most of the binary polymer systems were miscible, whereas the other combinations of DS and VP values led to an immiscible series of blends, a possible exception being the miscible pair of DS = 2.70 and VP = 100 mol‐%. Results of FT‐IR and solid‐state 13C CP/MAS NMR spectra measurements suggested the miscibility to be driven by the hydrogen‐bonding interaction between the residual hydroxyls of CA and the carbonyls of VP units in P(VP‐co‐MMA), as in the case of CA/P(VP‐co‐VAc) blends where the range of miscible pairing of acetyl DS and VP fraction was rather wide. From evaluations of proton spin‐lattice relaxation times in the NMR study, it was confirmed that the homogeneity of the miscible blends of CA/P(VP‐co‐MMA) was substantially on a scale within a few nanometers. To interpret the difference in the DS‐ and copolymer composition‐dependence of the miscibility behavior between three blend systems, CA/P(VP‐co‐MMA), CA/P(VP‐co‐VAc), and CB/P(VP‐co‐VAc), Krigbaum‐Wall intermolecular interaction parameters were estimated by solution viscometry for different polymer pairs pertinent to those blends. In particular, discussion took into consideration the effectiveness of an intramolecular repulsive action between the two units (VP and VAc, or VP and MMA) constituting the vinyl copolymers.magnified image

Production and properties of holographic photopolymeric material in a hybrid sol-gel matrix

This paper describes a method of obtaining a holographic photopolymer material 0.5-1 mm thick in a hybrid organic-inorganic matrix and the results of investigating it as a recording medium of 3D holographic memory, as well as for fabricating templates of 2D and 3D photonic crystals. To obtain such a material, a copolymer of vinylpyrrolidone with triethoxyvinylsilane was synthesized, followed by hydrolytic condensation of the given copolymer with tetraethoxysilane presol. It is shown that a solid sol-gel matrix that is stable against cracking can be formed with a presol:copolymer weight ratio of 1:4.

Relaxation Properties of Pressure-sensitive Adhesives upon Withdrawal of Bonding Pressure

ABSTRACT Relaxation properties of pressure-sensitive adhesives (PSA) have been studied with the squeeze-recoil tester used in the regime of parallel-plate dilatometer under conditions imitating the removal of compressive force in the course of adhesive bond formation. The relaxation properties of PSAs are compared with their adhesive behavior measured using the 180-Deg Peel Test. Two classes of PSAs are considered: 1) conventional rubbery adhesives based on the mixtures of styrene-isoprene-styrene (SIS) block copolymer with a tackifier resin and a plasticizer, and butyl rubber plasticized with low-molecular-weight polyisobutylene, and 2) hydrophilic PSAs composed of the blends of high-molecular-weight poly(N-vinyl pyrrolidone) (PVP) with oligomeric polyethylene glycol (PEG). By comparing the adhesive and relaxation behaviors of different PSAs, the relaxation criteria for pressure-sensitive adhesion have been stated. Relaxation behavior of the examined PSAs demonstrates two values of retardation time: the shorter retardation time of 10–70 sec and the longer time of 300–660 sec. These times can be associated, respectively, with small- and large-scale mechanisms of strain recovery. By comparing the relaxation and adhesive properties of PVP-PEG blend (which involves the formation of a hydrogen-bonded network through both terminal hydroxyl groups in PEG short chains) with the properties of covalently crosslinked copolymers of vinyl pyrrolidone (VP) with PEG-diacrylate and comb-like VP copolymers with PEG-monomethacrylate, the contributions of covalent crosslinking and H-bonding network have been characterized.