Methacrylate hydrogels reinforced with bacterial cellulose

Composite hydrogels consisting of nanofibrous bacterial cellulose (BC) embedded in a biocompatible polymeric matrix of various methacrylates were synthesized by UV polymerization using the ‘ever‐wet’ technique. The effect of monomer(s) type and ratio, system dilution at polymerization, monomer(s) hydrophilicity, crosslink density and cellulose/hydrogel ratio was investigated. The effect of BC reinforcement on equilibrium swelling depends on whether the neat gel swells more when brought into contact with water. The major improvement achieved by introduction of 1%–2% BC concerns mechanical properties. Compared with neat gels, the storage shear modulus G′ increased by a factor 10‐20, and the loss part G″ also rose significantly. The compression modulus ranged from 2 to 5.5 MPa for composites swollen to equilibrium (20‐70 wt% water). The BC‐hydrogel composites are considered for application in the tissue engineering area. Copyright © 2012 Society of Chemical Industry     

Heterogeneous and homogeneous structure dextran–poly(methacrylic acid) interpenetrating network hydrogels: synthesis and an application study

pH‐sensitive dextran–poly(methacrylic acid) (Dext–pMeAc) full interpenetrating network hydrogels (INHs) were prepared by simultaneous radical polymerization of methacrylic acid monomer (MeAc) and Dext polymer chains in the presence of N,N‐methylenebisacrylamide (MBA) as crosslinker in aqueous solution. These hydrogels were investigated as a drug carrier. The influence of MeAc and MBA contents in the network hydrogels on the swelling behaviour and mechanical strength of prepared Dext–pMeAc INHs was evaluated. Dext–pMeAc INHs were characterized by Fourier transform IR spectroscopy, and kinetic swelling measurements were carried out in deionized water and in simulated gastric fluids (pH 1.1 and pH 7.4). Dext–pMeAc/1‐1, Dext–pMeAc/3‐1 and Dext–pMeAc/5‐1 hydrogels with molar ratios of n_Dext/n_MeAc = 10 and n_MBA/n_Dext = 10, 30 and 50 respectively showed a core–shell structure when they swelled. This phenomenon was not observed in Dext–pMeAc/5‐2, Dext–pMeAc/5‐3 and Dext–pMeAc/5‐5 hydrogels containing a higher amount of Dext in the gels. The swelling data proved the formation of INHs with pH‐sensitive behaviour. A drug release study was performed using Rhodamine 6G fluorescent dye as a model hydrophilic bioactive molecule. The in vitro release rate of Rhodamine 6G from Dext–pMeAc/5‐3 hydrogel was dependent on the pH of the release medium. Copyright © 2012 Society of Chemical Industry     

Photosensitive antibacterial and cytotoxicity performances of a TiO2/carboxymethyl chitosan/poly(vinyl alcohol) nanocomposite hydrogel by in situ radiation construction

Nano‐TiO₂/carboxymethyl chitosan (CMCS)/poly(vinyl alcohol) (PVA) ternary nanocomposite hydrogels were prepared by freezing–thawing cycles and electron‐beam radiation with PVA, CMCS, and nano‐TiO₂ as raw materials. The presence of nano‐TiO₂ nanoparticles in the composite hydrogels was confirmed by thermogravimetry, Fourier transform infrared spectroscopy, and X‐ray powder diffraction. Field emission scanning electron microscopy images also illustrated that the TiO₂/CMCS/PVA hydrogel exhibited a porous and relatively regular three‐dimensional network structure; at the same time, there was the presence of embedded nano‐TiO₂ throughout the hydrogel matrix. In addition, the nano‐TiO₂/CMCS/PVA composite hydrogels displayed significant antibacterial activity with Escherichia coli and Staphylococcus aureus as bacterial models. The antibacterial activity was demonstrated by the antibacterial circle method, plate count method, and cell density method. Also, with the Alamar Blue assay, the cytotoxicity of the composite hydrogel materials to L929 cells was studied. The results suggest that these materials had no obvious cytotoxicity. Thus, we may have developed a novel, good biocompatibility hydrogel with inherent photosensitive antibacterial activity with great potential for applications in the fields of cosmetics, medical dressings, and environmental protection. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44150.     

Thermally crosslinked anionic hydrogels composed of poly(vinyl alcohol) and poly(γ‐glutamic acid): Preparation,characterization, and drug permeation behavior

pH‐sensitive anionic hydrogels composed of poly(vinyl alcohol) (PVA) and poly(γ‐glutamic acid) (γ‐PGA) were prepared by the freeze drying method and thermally crosslinked to suppress hydrogel deformation in water. The physical properties, swelling, and drug‐diffusion behaviors were characterized for the hydrogels. In the equilibrium swelling study, PVA/γ‐PGA hydrogels shrunk in pH regions below the pK_a (2.27) of γ‐PGA, whereas they swelled above the pK_a. In the drug‐diffusion study, the drug permeation rates of the PVA/γ‐PGA hydrogels were directly proportional to their swelling behaviors. The cytocompatibility test showed no cytotoxicity of the PVA/γ‐PGA hydrogels for the 3T3 fibroblast cell lines. The results of these studies suggest that hydrogels prepared from PVA and γ‐PGA could be used as orally administrable drug‐delivery systems. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Thermoreversible hydrogel. XVII. Investigation of the drug release behavior for [N‐isopropylacrylamide‐co‐trimethyl acrylamidopropyl ammonium iodide‐co‐3‐dimethyl (methacryloyloxyethyl) ammonium propane sulfonate] copolymeric hydrogels

A series of copolymeric hydrogels were prepared from various molar ratios of N‐isopropylacrylamide (NIPAAm), trimethyl acrylamidopropyl ammonium iodide (TMAAI), and 3‐dimethyl (methacryloyloxyethyl) ammonium propane sulfonate (DMAPS). Results showed that the swelling ratios of these copolymeric hydrogels increased with an increase of TMAAI content. The drug release behavior of the ionic thermosensitive hydrogels related to their ionicity and drug types. Results indicated that the release ratio of caffeine in the hydrogels was not affected by the ionicity of hydrogels, but increased with increasing of the swelling ratio. The anionic solute (phenol red) strongly interacted with cationic hydrogel (very large K_d), so the phenol red release ratio in cationic gels was very low. On the other hand, CV was adsorbed only on the skin layer of the cationic hydrogel because of the charge repulsion, and released rapidly. Therefore the release ratio was highest for cationic hydrogel to cationic drug. In addition, the partition coefficients (K_d) and the drug delivery behavior of the present gels were also investigated. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1592–1598, 2002     

Influence of particle size and fluid fraction on rheological and extrusion properties of crosslinked hyaluronic acid hydrogel dispersions

Crosslinked hyaluronic acid (HA) hydrogels are widely used in gel/HA fluid formulations as a viscosupplement to treat joint diseases; thus, it is important to characterize these hydrogels in terms of their particle size and to investigate the effects of the gel/fluid mixtures on their rheological properties and extrusion force. Hydrogels previously crosslinked with divinyl sulfone were sheared in an Ultra‐Turrax unit to produce particles with mean diameters ranging from 20 to 200 μm. Hydrogels with 75–100 μm mean diameters were also evaluated in dispersions containing a 20–40% mass fraction of HA fluid. The mean diameters were measured by laser light scattering and the rheological behavior was determined by oscillatory and steady measurements in parallel plate geometry. The HA hydrogels exhibited the typical behavior of so‐called weak gels, as analyzed by the storage and loss moduli G′ and G″, respectively. The viscoelasticity, the viscosity, and the extrusion force increased with the hydrogel particle size. The fluid phase dispersions decreased both moduli. At 40% fluid fraction, the gel characteristics were lost and the dispersion behaved as a fluid. Based on these results, the particle size and HA fluid fraction in hydrogel dispersions may be optimized to develop more efficient viscosupplement formulations. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Hydrogels reinforced with nanoclays with improved response rate

Two series of semiinterpenetrating networks (SIPN) based on linear hydrophilic poly(vinyl alcohol) (PVA) and thermo‐responsive poly(N‐isopropylacrylamide) (PNIPA), physically crosslinked with inorganic clay, are presented. The hydrogels with different crosslinking densities were prepared by varying the content of clay from 1 to 6 wt % and contained linear interpenetrant, PVA in the range of 0.5–1.5 wt %. The effect of clay content on swelling/deswelling behavior and phase transition in PNIPA gels, as well as the feasibility of reinforcing the gels with high molecular weight PVA, were analyzed. The thermal response of hydrogels, followed by DSC, confirmed that the insertion of hydrophilic PVA did not have a significant effect on the onset of the volume phase transition temperature, while the response was faster. The equilibrium degree of swelling of SIPNs and PNIPA hydrogels was in the range of 9–79 and decreased with increasing content of clay. The internal morphology and surface wettability of the hydrogels were investigated by scanning electron microscope analysis and contact angle measurements, respectively. The network structural parameters of the PNIPA and SIPN nanocomposites hydrogels, such as the average molecular weight between crosslinks, M_c, and effective crosslinking density, N_e, were determined by dynamic mechanical analysis. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44535.     

Modified carrageenan. 4. Synthesis and swelling behavior of crosslinked κC‐g‐AMPS superabsorbent hydrogel with antisalt and pH‐responsiveness properties

To synthesize a novel biopolymer‐based superabsorbent hydrogel, 2‐acrylamido‐2‐methylpropanesulfonic acid (AMPS) was grafted onto kappa‐carrageenan (κC) backbones. The graft copolymerization reaction was carried out in a homogeneous medium and in the presence of ammonium persulfate (APS) as an initiator, N,N,N′,N′‐tetramethyl ethylenediamine (TMEDA) as an accelerator, and N,N′‐methylene bisacrylamide (MBA) as a crosslinker. A proposed mechanism for κC‐g‐AMPS formation was suggested and the hydrogel structure was confirmed using FTIR spectroscopy. The affecting variables on swelling capacity, i.e., the initiator, the crosslinker, and the monomer concentration, as well as reaction temperature, were systematically optimized. The swelling measurements of the hydrogels were conducted in aqueous solutions of LiCl, NaCl, KCl, MgCl₂, CaCl₂, SrCl₂, BaCl₂, and AlCl₃. Due to the high swelling capacity in salt solutions, the hydrogels may be referred to as antisalt superabsorbents. The swelling of superabsorbing hydrogels was measured in solutions with pH ranging 1 to 13. The κC‐g‐AMPS hydrogel exhibited a pH‐responsiveness character so that a swelling–deswelling pulsatile behavior was recorded at pH 2 and 8. The overall activation energy for the graft copolymerization reaction was found to be 14.6 kJ/mol. The swelling kinetics of the hydrogels was preliminarily investigated as well. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 255–263, 2005     

Rheological and thermal properties of saponified cassava starch‐g‐poly(acrylamide) superabsorbent polymers varying in grafting parameters and absorbency

Cassava starch‐graft‐poly(acrylamide) superabsorbent polymers (SAPs) with varying absorbencies were synthesized. Weight average molecular weight (M_w) of the hydrolyzed starch‐graft‐copolymers ranged from 1.6 × 10⁶ to 2.8 × 10⁶ g/mol, the largest being shown by the sample with highest percentage grafting. The storage (G′) and loss modulus (G″) of hydrogels were determined as a function of frequency. G″ was larger than G′ for the hydrogels with higher absorbencies and exhibited a liquid‐like behavior. However, hydrogels with lower absorbencies showed a reverse viscoelastic behavior. The viscosity of hydrogels determined using a Brookfield viscometer at different shear rates was found to be larger for the hydrogels with higher absorbencies. The melting temperature (T_m) and enthalpy change of fusion (ΔH_f) of the SAPs ranged from 149.7 to 177.7°C and 65 to 494.9 J/g, respectively and showed a positive correlation with grafting parameters and M_w. Heavy metal ion removal capacity of hydrogel followed the order Cu²⁺ > Pb²⁺ > Zn²⁺. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40368.     

State of water in chitosan–PVA hydrogel

The bound water fraction (X_BW) of a newly‐ developed pH‐sensitive, biodegradable chitosan‐polyvinyl alcohol (PVA) hydrogel crosslinked with glutaraldehyde (GA) was investigated as a function of the chitosan/PVA molar ratio, GA concentration (C_GA), and ionization state. Differential scanning calorimetry (DSC) was used to determine the X_BW of the initial hydrogel, and of the hydrogel equilibrated in pH 3 and pH 7 buffers. Changes in X_BW during swelling and shrinking of hydrogel were also investigated. In the initial state of hydrogel, X_BW increased with increasing PVA concentration (C_PVA), without being significantly affected by C_GA. In the buffer‐equilibrated hydrogels, X_BW decreased with increasing C_PVA and decreasing C_GA. The amount of bound water based on dry mass (C_BW) was substantially higher when the hydrogel was in the ionized (swollen) state compared to its unionized counterpart. This may be due to the association of a large quantity of water molecules with ? NH₃⁺ groups of chitosan when the gel swelled in the acidic environment. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3227–3232, 2006     

Electrically conductive and mechanically tough graphene nanocomposite hydrogels with self‐oscillating performance

Conventional hydrogels are extremely brittle, fragile and poorly conductive, which limits their applications in a variety of aspects. In this study, we fabricated a novel kind of nanocomposite self‐oscillating hydrogel poly(AA‐co‐Fe(phen)₃)/PVA/RGO with high conductivity and good mechanical strength by dispersing reduced graphene oxide (RGO). Due to the synergetic effect of RGO dispersed in the hydrogels or dry gels and Fe metal which is the reduction product of the Fe(phen)₃ moiety by RGO, the hydrogels have a high conductivity of 18.2 S m^?1 with 0.67 wt% RGO content. The dispersed RGO in the hydrogels combined with the network structure by means of hydrogen bonding, π–π stacking and electrostatic interaction and was demonstrated to enhance the mechanical properties of the hydrogels. The elastic modulus achieves 65.2 kPa (1020% of the tensile strength) and 236.4 kPa (with 70% compression), respectively. In addition, the prepared hydrogels exhibit a self‐oscillating behavior in a Belousov–Zhabotinsky solution free of catalyst. These results can be broadly applied in the future in the development of an autonomous on–off switching, flexible/stretchable, graphene‐based soft electronic device. © 2019 Society of Chemical Industry     

Preparation and characterization of polyacrylic acid‐poly(vinyl alcohol)‐based interpenetrating hydrogels

Some structural features of hydrogels from poly(acrylic acid) (PAAc) of various crosslinking degrees have been investigated through mechanical and swelling measurements. Interpenetrating polymer hydrogels (IPHs) of poly(vinyl alcohol) (PVA) and PAAc have been prepared by a sequential method: crosslinked PAAc chains were formed in aqueous solution by crosslinking copolymerization of acrylic acid and N,N‐methylenebisacrylamide in the presence of PVA. The application of freeze–thaw (F–T) cycles leads to the formation of a PVA hydrogel within the synthesized PAAc hydrogel. The swelling and viscoelastic properties of the IPHs were evaluated as a function of the content of crosslinker and the application of one F–T cycle. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 5789–5794, 2006     

Preparation and characterization of PAM/SA tough hydrogels reinforced by IPN technique based on covalent/ionic crosslinking

In order to fabricate tough hydrogels with superior formability, polyacrylamide/sodium alginate (PAM/SA) interpenetrating polymer network (IPN) hydrogels were produced with ionically crosslinked SA interpenetrated in covalently crosslinked PAM. TGA results show that the heat resistance of PAM/SA IPN hydrogel is improved as compared to that of the individual component. Swelling studies indicate that increasing either chemical crosslinker content or ionic crosslinking via adding more N,N′‐methylenebisacrylamide (MBA) or SA results in lower ESR. It is concluded by tensile test that loosely crosslinked PAM coupled with tightly crosslinked SA improve mechanical strength for hydrogels based on covalent/ionic crosslinking. PAM/SA hydrogels via “one‐pot” method can form different complex shapes with mechanical properties comparable to conventional double network (DN) gels. The fracture strength of PAM_0.05/SA₂₀ reaches level of MPa, approaching 2.0 MPa. The work strives to provide method to tune mechanical and physical properties for hydrogels, which is hopefully to guide the design of hydrogel material with desirable properties. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41342.     

Characterization of strong polyelectrolyte hydrogels based on poly(vinyl alcohol)

Maleic anhydride (MA) was grafted onto both partially and fully hydrolyzed poly(vinyl alcohol) (PVA) in the presence of an initiator. Strong polyelectrolyte polymers were prepared by sulfonation of PVA–MA grafts. The sulfonation was completed by reaction of hydroxyl groups of PVA–MA grafts with two different sulfonating reagents (chlorosulfonic acid and pyridine sulfonic acid). The sulfonation degree was evaluated by acid–base titration and ¹H NMR analysis. The solution behaviour of the prepared grafts was evaluated from viscosity measurements. Four kinds of water‐insoluble PVA–MA and PVA–MA‐SO₃H hydrogels were prepared by heat treatment, physical gelation and chemical crosslinking with different weight ratios of N,N‐methylene bisacrylamide (MBA) crosslinker. The swelling parameters were measured for all prepared gels in deionized water and aqueous solutions at different pH values from 2 to 12 having constant ionic strength (I = 0.1). All gels exhibit a different swelling behaviour upon environmental pH changes. Copyright © 2004 Society of Chemical Industry     

Properties of hydrogels of atactic poly(vinyl alcohol)/NaCl/H2O system and their application to drug release

In order to prepare cost‐effective physically cross‐linked hydrogels including food salt sodium chloride, samples, were prepared with various concentrations of NaCl and respective atactic poly(vinyl alcohol) (a‐PVA), and were evaluated. It had been observed that hydrogels containing NaCl concentration (9–11 wt%) along with a‐PVA concentration 9–5% respectively exhibited higher melting points (91.5–95.1 °C). A higher melting point characterizes the hydrogel composition of a system like a‐PVA(7%)/NaCl(11%)/H₂O. The swelling degree of this hydrogel was found to be comparatively better at 37 °C than at any other temperature studied here. However, irregular Fickian swelling was found at this temperature. The UV light absorption maximum at 362–364 nm and minimum at 351 nm for this hydrogel had been found as evidence of physical cross‐linking. A drug, theophylline was loaded by solvent‐sorption and feed‐mixture dissolving methods. The feed‐mixture dissolving method is better than solvent sorption because of high drug loading, comparatively low fraction release rate and more sustained‐release of drug than that of solvent‐sorption. Theophylline was released twice as fast from the hydrogel after solvent‐sorption drug loading (3 h) than from that which used the feed‐mixture dissolving method (6.5 h). Theophylline‐loaded hydrogels of this system (feed‐mixture dissolving) were then prepared at high temperature (60 °C) thawing for 6 h followed by chilling at 0.4 °C for 3 h as one cycle. And the drug release behaviour and mass transfer were found almost the same as for chilling (24 h at 0.4 °C)–thawing (48 h at room temperature). Drug release behaviour was studied as apparently irregular Fickian diffusion (Higuchi Matrix Dissolution Model). © 2002 Society of Chemical Industry     

Effect of stereoregularity and molecular weight on the mechanical properties of poly(vinyl alcohol) hydrogel

The effect of the stereoregularity and molecular weight of poly(vinyl alcohol) (PVA) on the mechanical properties of hydrogel was investigated. Compressive strength, creep behavior, and dynamic viscoelasticity were measured on hydrogels of syndiotacticity‐rich PVA derived from poly(vinyl pivalate) (D_p = 1690 diad‐syndiotacticity = 61%, D_p = 8020 diad‐syndiotacticity = 62%) and atactic PVA (D_p = 1750 diad‐syndiotacticity = 54%, D_p = 7780 diad‐syndiotacticity = 54%). Increasing the molecular weight of molecular chains constituting the gel improved the compressive strength of atactic PVA hydrogel. The stereoregularity of PVA had a greater effect than molecular weight on the strength of the hydrogel. Gel prepared from 8.8 g/dL syndiotacticity‐rich PVA had a high compressive modulus of 10 kPa, and the compressive modulus of the gel prepared from 3.3 g/dL was comparable with that of atactic PVA hydrogel prepared with more than 6 g/dL. The dynamic storage modulus of the gel derived from syndiotacticity‐rich PVA was remarkably higher than that of the atactic PVA gel and remained constant up to 60°C. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Facile synthesis of biocompatible polyglycerol hydrogel based on epichlorohydrin

A series of hydrophilic polyglycerol (PG) hydrogel was designed and synthesized via one pot with epichlorohydrin (ECH), H₂O, and NaOH as the starting materials. The equilibrium swelling ratios of PG hydrogels could be tuned by simply changing the feed amount of NaOH. The gels were characterized by carbon nuclear magnetic resonance (¹³C NMR) spectroscopy, X‐ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy. The As‐synthesized PG hydrogels showed temperature‐sensitive swelling behaviors. The results of MTT assay suggested that the PG hydrogels prepared by this novel synthesis method showed comparable cytocompatibility with the recognized poly(ethylene glycol) hydrogel. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43451.     

Silicon dioxide/poly(vinyl alcohol) composite hydrogels with high mechanical properties and low swellability

Poly(vinyl alcohol) (PVA) hydrogels with tissue-like viscoelasticity, excellent biocompatibility, and hydrophilicity have been considered as promising cartilage replacement materials. However, the low mechanical properties of pure PVA hydrogels limit their applications for bearing complicated loads. Herein, we report silicon dioxide (SiO₂)/PVA composite hydrogels fabricated by fabricated cyclically freezing/thawing the aqueous mixture of PVA and methyltrimethoxysilane (MTMS). MTMS hydrolyzes and forms SiO₂ particles in situ to reinforce PVA hydrogel. Meanwhile, silanol group condenses with hydroxyl groups of PVA and chemically bonds with PVA. The resulting SiO₂/PVA hydrogels exhibit much better mechanical properties than bare PVA hydrogel. In addition, the composite hydrogels keep very low swellable property. This prepared composite hydrogels are promising in a variety of biomedical applications such as artificial articular cartilage, drug delivery, and biosensors. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 46895.     

Controlled mechanical and swelling properties of poly(vinyl alcohol)/sodium alginate blend hydrogels prepared by freeze–thaw followed by Ca2+ crosslinking

Poly(vinyl alcohol) (PVA)/sodium alginate (SA) blend hydrogels have immense potential for use as functional biomaterials. Understanding of influences of processing parameters and compositions on mechanical and swelling properties of PVA/SA blend hydrogels is very important. In this work, PVA/SA blend hydrogels with different SA contents were prepared by applying freeze–thaw method first to induce physical crosslinking of PVA chains and then followed by Ca²⁺ crosslinking SA chains to form interpenetrating networks of PVA and SA. The effects of number of freeze–thaw cycles, SA content and Ca²⁺ concentration on mechanical properties, swelling kinetics, and pH‐sensitivity of the blend hydrogels were investigated. The results showed that the blend hydrogels have porous sponge structure. Gel fraction, which is related to crosslink density of the blend hydrogels, increased with the increase of freeze–thaw cycles and strongly depended on SA content. The SA content exerts a significant effect on mechanical properties, swelling kinetics, and pH‐sensitivity of the blend hydrogels. The number of freeze–thaw cycles has marked impact on mechanical properties, but no obvious effect on the pH‐sensitivity of the PVA/SA blend hydrogels. Concentration of CaCl₂ aqueous solution also influences mechanical properties and pH‐sensitivity of the blend hydrogel. By altering composition and processing parameters such as freeze–thaw cycles and concentration of CaCl₂ aqueous solution, the mechanical properties and pH‐sensitivity of PVA/SA blend hydrogels can be tightly controlled. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Miscibility and pressure‐sensitive adhesive performances of acrylic copolymer and hydrogenated rosin systems

Relationship between the miscibility of pressure‐sensitive adhesives (PSAs) acrylic copolymer/hydrogenated rosin systems and their performance (180° peel strength, probe tack, and holding power), which was measured over a wide range of time and temperature, were investigated. The miscible range of the blend system tended to become smaller as the molecular weight of the tackifier increased. In the case of miscible blend systems, the viscoelastic properties (such as the storage modulus and the loss modulus) shifted toward higher temperature or toward lower frequency and, at the same time, the pressure‐sensitive adhesive performance shifted toward the lower rate side as the T_g of the blend increased. In the case of acrylic copolymer/hydrogenated rosin acid systems, a somewhat unusual trend was observed in the relationship among the phase diagram, T_g, and the pressure‐sensitive adhesive performance. T_g of the blend was higher than that expected from T_gs of the pure components. This trend can be due to the presence of free carboxyl group in the tackifier resin. However, the phase diagram depended on the molecular weight of the tackifier. The pressure‐sensitive adhesive performance depended on the viscoelastic properties of the bulk phase. A few systems where a single T_g could be measured, despite the fact that two phases were observed microscopically, were found. The curve of the probe tack of this system shifted toward a lower rate side as the T_g increases. However, both the curve of the peel strength and the holding power of such system did not shift along the rate axis. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 651–663, 1999