Weight Of Polyethylene Glycol Research Articles

Heterometallic [2]Catenane-Crosslinked Supramolecular Networks with Improved Antibacterial Activity.

The construction of supramolecular networks with novel crosslinks is of great significance in expanding their chemical structures and exploring their advanced functions. Herein, we prepare a type of [2]catenane-cored supramolecular networks based on the crosslinking of polyethylene glycol (PEG) using a heterometallic [2]catenane unit. By adjusting the molecular weight of PEG, the solubility of the networks can be tuned and gels are formed using low molecular weight PEG. The introduction of heterometallic [2]catenane offers the networks good antibacterial properties owing to the synergistic antimicrobial activity of Pt(II) and Cu(I) ions in the [2]catenane. This study provides a simple and efficient strategy for constructing supramolecular networks with topological crosslinks as antibacterial materials, which will promote the structural design and biological applications of supramolecular networks.

Fabrication and characterization of PEGylated magnetite nanoparticles for sustained curcumin release: in-vitro study

Abstract A novel approach was adopted to synthesize size-controlled magnetite nanoparticles (MNPs) coated with different molecular weights of polyethylene glycol (PEG), like PEG 750, PEG 2000, and PEG 5000. The drug release kinetics of curcumin (CPMNPs) loaded PEGylated samples were studied. Different techniques used to characterize nanoparticles, like transmission electron microscopy (TEM), x-ray diffraction (XRD) analysis, Fourier transform infrared (FTIR) spectroscopy, and thermogravimetric analysis (TGA). The in-vitro studies of curcumin from CPMNPs samples observed a sustained release through kinetics studies from the PMNPs that followed a pseudo-second order reaction. MNPs functionalized with different molecular weights of PEG to make the MNPS biocompatible; moreover, the role of PEG on sustained release of curcumin was also investigated. It was concluded that the particles synthesized at pH-10 coated with PEG of molecular weight 750 exhibited the highest sustained release efficiency of curcumin, i.e., about 98.8%.

Evaluation of the Chemical Structure and Thermal Properties of Polyethylene Glycol (PEG)-Doped Polylactic Acid (PLA)/Multiwalled Carbon Nanotube (MWCNT) Composites

This study aimed to investigate the chemical structure, thermal properties, and stability of polylactic acid (PLA) composites blended with multi-walled carbon nanotubes (MWCNTs) and polyethylene glycol (PEG). The composites were fabricated using a masterbatch blending method with two different molecular weights (Mw) of PEG. The masterbatch was initially prepared using solvent casting with chloroform as the solvent, followed by melt blending using an extruder. ATR-FTIR spectroscopy identified strong hydrogen bonds between the C=O groups of PLA and the –OH groups of PEG, as evidenced by the peak at 1748 cm¹. Differential Scanning Calorimetry (DSC) revealed that incorporating 14 wt% of PEG 10,000 into PLA/MWCNT composite significantly enhances the melting enthalpy (∆Hm) from 18.3 J/g to 24.6 J/g and the degree of crystallinity from 2% to 17.3%. The glass transition temperature (Tg) decreased with the addition of PEG, indicating increased chain mobility, while the melting temperature (Tm) remained relatively constant around 158 oC regardless of the PEG Mw. Despite the plasticizing effect of PEG, the thermal stability of the composites was maintained across different PEG Mw. Scanning Electron Microscope (SEM) images showed that MWCNTs were well dispersed within the blend, facilitated by ultrasonic stirring during preparation.

Design of flexible polyethylene glycol-based phase change materials by crystal structure regulation

The design of flexible phase change materials (FPCMs) with polyethylene glycol (PEG) as phase change components remains a great challenge due to high crystalline structure makes for high thermal energy storage ability yet deteriorates mechanical toughness. Herein, the preparation strategy of FPCMs was developed by introducing crystal structure regulators (CSRs) in PEG-based FPCM networks in a form of covalent linkages. The hydroquinone CSR had the strongest ability of crystal structure regulation over FPCMs compared to the three other used CSRs. The FPCMs had tuneable phase change temperatures (−2.0 °C–49.7 °C) and enthalpies (40.7 J g−1 to 109.3 J g−1) depending on the number-average molecular weight (Mn = 4000 Da, 6000 Da) of PEGs used as well as the content and type of CSRs, further enabling tuneable mechanical stress (0.59–15.61 MPa) and strain (5.74%–505.86 %). Compared with the pristine PEGs, the FPCMs yielded excellent shape stability, thermal stability and thermal reliability. The flexibility and phase change properties endowed the FPCMs with excellent self-adaptability and shape memory function. The innovative strategy towards FPCMs highlights the application potential on individual wearable temperature-controlled devices.

The Effect of a Hydrophilic Polymer on the Morphology of Polymeric Membranes and the Retention of Metals

Polyethylene glycol (PEG) is a preferred hydrophilic polymer as an additive for casting solutions. In this study, polymeric membranes containing 1,10-phenanthroline and different molecular weights of polyethylene glycol (PEG) are tested for the morphological change and metal retention on the membrane surface. Additives in the form of PEGs with molecular weights of 400 Da, 600 Da, and 6000 Da were used. The morphology of each membrane was examined using scanning electron microscopy (SEM). It appears that copper has more retention than cadmium in all membrane components in SEM–EDS analysis. FTIR spectra findings provided evidence that PEG binds to the PVC backbone through hydrogen bonds involving chlorine atoms in the PVC and hydrogen atoms in the hydroxyl groups of PEG. The porosity of the membrane was determined by gravimetric method. The molecular weight of PEG in the membrane seems to be increasing, the porosity of the membrane improved. The porosity of the membrane obtained with PVC/ PEG/ 1,10-phenanthroline is 62.85 for PEG 400, 80.00 for PEG 600 and 83.50 for PEG 6000. The order of metal retention on the surface of the membranes consisting of PVC-1,10 phenanthroline and PEGs are Cu > Cd, indicating that with its large diameter (140 pm), cadmium cannot settle into the pores as much as copper. Except for PEG 600, the retention of both metals decreased with the addition of phenanthroline to the membrane containing PEG. The amorphous structure was detected from the XRD of the membranes. Thermal analysis of the membrane was determined by TG-DSC.Graphical

Fluorescence visualization of CO2-responsive phase transfer materials targeting at the heterogeneous interfacial reactions in advanced oxidation of naphthenic acid in wastewater

Treatment of naphthenic acids (NAs) in wastewater is necessary due to its high toxicity and difficult degradation. In the heterogeneous Fenton-like advanced oxidation of organic pollutant system, the insufficient accessibility of oxidizing agent and NAs greatly hamper the reaction efficiency. CO2-responsive phase transfer materials derived from polyethylene glycol (PEG)-based deep eutectic solvents were specific targeted at the immiscible-binary phase system. The NAs oxidative degradation process was optimized including the kinds of catalyst (Molecular weight of PEG, constitute of DESs, and dosage.), temperature, flow rate of CO2, et al. With the help of fluorescence properties of catalyst, the hydrophilic-hydrophobic interaction was visual-monitored and further studied. The amphipathic property of PEG-200/Sodium persulfate/Polyether amine 230 (PEA230) greatly reduced the aqueous/organic phase transfer barrier between sodium persulfate and NAs (up to 84 %), thus accreting oxidation rate. The surface tension decreased from 35.364 mN/m to 28.595 mN/m. To control the reaction rate, the CO2 respond structure of amido played an important role. In addition, the interfacial transfer intermediates and oxidation pathways were also explored by nuclear magnetic resonance, flourier transform infrared spectroscopy, surface tension, and radical inhibition experiments. The mechanism of advanced oxidation of NAs catalyzed by CO2-responsive phase transfer catalyst was proposed, which would made up for the deficiency of the system theory of heterogeneous chemical oxidation of organic pollutants.

Diffusion mediated thermally induced phase separation for preparing poly(vinylidene fluoride) membranes with enhanced separation performances

Thermally induced phase separation (TIPS) process is an appealing method for preparing poly(vinylidene fluoride) (PVDF) membranes for separation. In this work, we developed a diffusion mediated thermally induced phase separation (d-TIPS) to prepare PVDF membranes with great molecules separation performances. We investigated the thermodynamics of ternary polymer solutions including PVDF, caprolactam (CPL), and Polyethylene glycol (PEG). We controlled liquid–liquid phase separation and the CPL diffusion by adjusting the addition of PEG and molecular weight to modulate the evolution of morphology from spherulitic to bicontinuous structure. The resulting membrane was characterized by morphology, surface chemistry, tensile strength, water contact angle, and perm-selectivity. The membrane was further stretched for enhanced strength, permeance, and rejection. This work provides a fundamental understanding of the diffusion mediated thermally induced phase separation and shows the great potential of PVDF membranes in macromolecules separation.

Preparation and performance analysis of polyethylene glycol/epoxy resin composite phase change material

It is crucial for their widespread application to develop phase change materials (PCMs) that can be mass-produced and possess high thermal storage capacity and stability. This study uses polyethylene glycol (PEG) as the phase change material and epoxy resin as the matrix to prepare polyethylene glycol/epoxy resin composite phase change materials (EPPCM) by blending and analyzing the effects of PEG's molecular weight and content on EPPCM's performance. The results indicate that PEG and epoxy resin are physically blended without chemical reaction. When the molecular weight of PEG is fixed, the larger the content of PEG, the higher the crystallinity, phase change enthalpy value, and phase change temperature of EPPCM, and the weaker the thermal cyclic stability and mechanical properties. When the content of PEG is fixed, the larger the molecular weight of PEG, the higher the crystallinity, phase change enthalpy value, and phase change temperature of EPPCM, the stronger the thermal cyclic stability, and the weaker the mechanical properties. Using PEG-10000 as the PCM with a PEG to epoxy resin ratio of 1:2.5, the EPPCM shows a phase change exothermic temperature range of 33.4 °C to 45.7 °C, an endothermic temperature range of 54.3 °C to 65.4 °C, a phase change enthalpy of 130.0 J/g, and only 1.56 % mass loss after 30 phase change cycles.

A study on influence of wettability on antiviral coating using polyethylene glycol (PEG) and acrylic binder

Abstract One of the biggest problems facing medical science today is preventing viral outbreaks, which highlights the significance of research initiatives aimed at creating antimicrobial coatings for a range of products, including textiles, medical devices, and public spaces. In this study, we aimed to determine the possible antiviral effects of polyethylene glycol (PEG) coating on feline coronavirus (FCoV). The PEG coatings were synthesized by a simple mixing method with a water-based acrylic binder in different weight percentages (3, 5, 10, 15, 20, and 25 wt%). The Spearman–Karber technique was used to calculate the viral titers, which were then expressed as the tissue culture infectious dose at 50 % CPE (TCID50/ml). 20 wt% PEG could result in a 3 log10 reduction in virus titer with an inhibition rate of approximately 99.9 % against FCoV. The increment of PEG weight percent from 0 to 25 wt% decreases the hardness and glass transition temperature of the coatings from 38.1 to 5.5 HV and 15.45 to −15.48 °C. Apart from that, the wettability analysis has revealed that PEG coating is hydrophilic with water contact angle (WCA) of around 75 ± 0.5°–85 ± 0.5°. Adding 25 wt% of PEG makes the coating to be superhydrophilic with WCA of 39.85 ± 0.5°.

Green, recyclable and high latent heat form-stable phase change composites supported by cellulose nanofibers for thermal energy management

Efficiently addressing the challenge of leakage is crucial in the advancement of solid-liquid phase change thermal storage composite materials; however, numerous existing preparation methods often entail complexity and high energy consumption. Herein, a straightforward blending approach was adopted to fabricate stable phase change nanocomposites capitalizing on the interaction between TEMPO-oxidized cellulose nanofibers (TOCNF) and polyethylene glycol (PEG) molecules. By adjusting the ratio of TOCNF to PEG and the molecular weights of PEG, TOCNF/PEG phase change composites (TPCC) with customizable phase transition temperature (40.3–59.1 °C) and high phase transition latent heat (126.3–172.1 J/g) were obtained. The TPCC of high-loaded PEG (80–95 wt%) ensured a leakage rate of less than 1.7 wt% after 100 heating-cooling cycles. Moreover, TPCC exhibits excellent optical properties with a transmittance of over 90 % at room temperature and up to 96 % after heating. The thermal response analysis of TPCC demonstrates exceptional thermal-induced flexibility and good thermal stability, as well as recyclability and reshaping ability. This study may inspire others to design bio-based phase change composites with potential applications in thermal energy storage and management of smart-energy buildings, photothermal response devices, and waste heat-generating electronics.

Polyethylene glycol regulates the pitch and liquid crystal behavior of cellulose nanocrystal-based photonic crystals

Inspired by iridescent color in natural creations, cellulose nanocrystal (CNC) photonic crystals artificially created by nanotechnology have great application prospects due to their potential to control light propagation in the linear and nonlinear regimes. One of the most important development directions of photonic crystals is the diversification of colors, usually by adjusting the pitch. However, few researchers notice the effect of polymer molecular weight and content on pitch regulation and the interaction between polymer and CNC liquid crystals. Polyethylene glycol (PEG) were used as polymers to regulate the pitch of CNC photonic crystals and investigate the changes in microstructure, crystal structure, thermal properties, and liquid crystal texture of the composites by changing the PEG content and molecular weight. Different photonic crystal construction systems show that when the molecular weight of PEG is 0.4 k, it can be filled between CNCs to regulate the pitch of photonic crystals, while when the molecular weight of PEG is 20 k, it cannot always be filled between CNCs in evaporation-induced self-assembly (EISA) process due to the depletion interaction, which cannot effectively regulate the pitch. This study reveals the relationship between PEG and CNC liquid crystals, which supports the development of photonic crystals and the pitch regulation.

To Assess Drug Delivery System Nanocarrier at Industrial Production: Establishment of Liposomal Surface Using Physicochemical Properties

Liposomes have been reported to be useful nanocarrier, however, there are number of challenges to resolve before they can be optimized for drug delivery. Liposomes are taken up by cell in the reticuloendothelial system (RES). Polyethyleneglycol (PEG) modification on the liposomal membrane forms a fixed aqueous layer and thus prevents uptake by the RES. The physicochemical properties of liposomes that are most commonly evaluated particle size and zeta potential are not sufficient indicator of the passive targeting effect by PEG modification. In contrast, the fixed aqueous layer thickness (FALT) around liposomal surface was clear to be regulated to be the utilized action in the body. It was showed that the FALT value of PEG-modified liposomes containing doxorubicin increased with the increase in the molecular weight of PEG. Furthermore, PEG modification with a combination of high- and low- molecular weight PEGs on liposomal membranes showed in optimal results with respect to FALT and a higher antitumor effect. In addition, we designed and synthesized a novel PEG-lipid, different double arms PEG (DDA-PEG), which consisted of two PEG chains of 500 and 2000 in one molecule to develop more useful PEG-modified liposomes. DDA-PEG was found to have superior antitumor activity and was associated with the prevention of tumor metastasis. Furthermore, we sought to (-)-epigallocatechin-3-O-gallate (EGCG) functions as a target ligand of the 67-kDa laminin receptor (67LR), which is expressed on high-grade tumor cells. EGCG-PEG-modified liposome appear to have superior antitumor activity against high 67LR-expressing tumor cells, as the liposomes had dual effects.

Polycaprolactone/Starch/Agar Coatings for Food-Packaging Paper: Statistical Correlation of the Formulations' Effect on Diffusion, Grease Resistance, and Mechanical Properties.

Paper is one of the most promising materials for food packaging and wrapping due to its low environmental impact, but surface treatments are often needed to improve its performance, e.g., the resistance to fats and oils. In this context, this research is focused on the formulation of a new paper bio-coating. Paper was coated with liquids containing poly(hexano-6-lactone) (PCL), glycerol and variable percentages of starch (5-10% w/w PCL dry weight), agar-agar (0-1.5% w/w PCL dry weight), and polyethylene glycol (PEG) (5% or 15% w/w PCL dry weight) to improve coating uniformity and diffusion. A design of experiments approach was implemented to find statistically reliable results in terms of the best coating formulation. Coated paper was characterized through mechanical and physical properties. Results showed that agar content (1.5% w/w PCL dry weight) has a beneficial effect on increasing the resistance to oil. Furthermore, the best coating composition has been calculated, and it is 10% w/w PCL dry weight of starch, 1.5% w/w PCL dry weight of agar, and 15% w/w PCL dry weight of PEG.

Characterization of a chlorine resistant and hydrophilic TiO2/calcium alginate hydrogel filtration membrane used for protein purification maintaining protein structure

The development of membranes for protein purification has stringent requirement of disinfection resistance, low protein adsorption and anti-fouling, without changing protein structure. In this study, hydrophilic titanium dioxide (TiO2)/calcium alginate (TiO2/CaAlg) hydrogel membranes were prepared by a simple ionic cross-linking method. The effects of the porogenic agent polyethylene glycol (PEG) concentration, the molecular weight of PEG, and the concentration of TiO2 on the filtration properties were systematically investigated. The TiO2/CaAlg membrane exhibited excellent bovine serum albumin (BSA) rejection and anti-fouling properties. The mechanical properties and surface energy of the TiO2/CaAlg membrane were significantly improved. The chemical bonding mechanism of TiO2 and NaAlg was investigated by molecular dynamic simulation. The TiO2/CaAlg membrane had good chlorine resistance and could be disinfected or cleaned with sodium hypochlorite. The TiO2/CaAlg hydrogel membrane loaded with polyhydroxybutyrate (PHB) nanofibers maintained high flux (136.7 L/m2h) and high BSA rejection (98.0 %) at 0.1 MPa. The results of circular dichroism and synchronous fluorescence indicated that the secondary structure of BSA was maintained after membrane separation. This study provides one method for the preparation of green and environmentally friendly membrane for protein purification.

Quantification of macromolecule crowding at single-molecule level.

Macromolecule crowding has a prominent impact on a series of biochemical processes in the cell. It is also expected to promote macromolecular complexation induced by excluded volume effects, which conflicts with recent advances in the thermodynamic interaction between inert, synthetic polymers, and nucleic acids. Along this line, a method combining high-resolution magnetic tweezers and extended crowder-oxDNA model was applied to resolve these discrepancies by systematically studying the kinetics and thermodynamics of the folding-unfolding transition for an individual DNA hairpin in a crowded environment. More specifically, from the magnetic tweezers-based experiments, the linear dependence of the critical force of the DNA hairpin on the polyethylene glycol (PEG) concentration was demonstrated, which is consistent with the results based on the crowder-oxDNA model in which the Lennard-Jones potential was adopted to express the interaction between the crowders and the DNA hairpin. These consistencies highlight that the excluded volume effects are mainly responsible for the interaction between PEG and the DNA hairpin, which is different from the interaction between dextran and the DNA hairpin. In the meantime, the dependence of the folding rate on the molecule weight of PEG, which was different from fluorescence resonance energy transfer-based results, was identified. The proposed method opens a path to detect the interaction between an inert, synthetic molecule, and the DNA hairpin, which is important to accurately mimic the cytosolic environments using mixtures of different inert molecules.

Fluctuations of Dry and Total Mass of Cells Exposed to Different Molecular Weights of Polyethylene Glycol

Polyethylene glycol (PEG) is used in many applications, and in the clinical field, it is one of the main components of the latest Covid vaccines. Its wide use is justified by a relatively safe profile and few known side effects. However, little is known about the biophysical effects of PEG on cells such as, cell stiffness, dry mass, and total mass. Herein, exploiting a digital holographic microscope, an inertial picobalance, and a nanoindenter, these properties are characterized in rat embryonic fibroblast exposed to different molecular weights of PEG. Immediately after the first minutes of PEG exposure to the cells, a reduction in cell dry mass can be observed as well as a rapid fluctuation in total cell weight. Cell stiffness decreases significantly after 48 h, while no important morphological changes are observed. Here, it is revealed how dry mass and total mass are rapidly and finely regulated, highlighting how the maintenance of cell density is of primary importance in cellular activities.

Polymeric phase change material networks based on multi-telechelic polyethylene glycol-derived multimer structures for thermal energy storage

Multi-telechelic polyethylene glycol (PEG)-based multimers with multiple reactive groups at both ends of the molecular chains can be used to prepare solid–solid phase change materials (PCMs) networks with enhanced mechanical strength, shape stability, PEG weight and adjustability in crosslink density, denoted as multi-telechelic effect in this report. Herein, multi-telechelic PEG-based PCMs networks were synthesized via the crosslinking reactions between designed hydroxyl-terminated multi-telechelic PEG-based multimers and curing agents, whose parameters can be readily tuned by the structure of multi-telechelic PEG-based multimers, for example, the number of PEG-derived structural units and the functionality of curing agents. Compared to conventional di-telechelic diethanolamine (DEA)-cured PCMs (DPCMs), the multi-telechelic tri-hexamethylene diisocyanate-cured PCMs (TPCMs) increase to 8–50 times in the storage modulus while decreasing only by 9.4 % in melting latent heat (ΔHm). The ΔHm of TPCMs increases by 58.2 % from 77.0 J/g to 121.8 J/g with increasing the number of PEG-derived structural units (y) from 1 to 4 when PEG with a number-average molecular weight of 4 kDa was used. TPCMs possess fine shape and thermal stability as well as thermal reliability while the reprocessability of PCMs is endowed by introducing a transcarbamoylation catalyst. The multi-telechelic PEG-based multimers can provide an alternative approach towards high-performance PCMs networks.

Experimental investigation of heat transfer characteristics of polyethylene glycol (PEG) based quench media for industrial heat treatment

Aqueous polymer quenchants are now increasingly used in the quench hardening of steels. The inverse solubility property of polymer media leads to polymer film encapsulation of the quenched component, followed by an instantaneous rupture of the polymer film. The film boiling stage is absent, thus improving heat transfer uniformity. In the present investigation, the effect of molecular weight of Polyethylene glycol (PEG) on heat transfer characteristics of PEG/water quenchants with concentrations of 5, 10, and 20 vol% was studied. The cooling curve analysis is performed to assess the cooling characteristics. Spatially dependent surface heat flux transients are estimated using the inverse heat conduction method. The rewetting kinematics is analyzed by videography and acoustic analysis of polymer film rupture during quenching. The results indicated that an increase in the molecular weight of PEG from 200 to 6000 changed the rewetting kinematics from a local wetting front movement to an instantaneous rupture of the polymer film. The change in the rewetting kinematics is reflected in the surface heat flux, indicating an increased uniformity of heat transfer. The film rupture acoustics showed that the polymer film's instantaneous breakup had a higher sound intensity than the one showing wetting front motion.

Preparation and drug release performance of amphiphilic medical hot‐melt pressure sensitive adhesives based on polystyrene‐isoprene‐styrene

AbstractHot‐melt pressure‐sensitive adhesives (HMPSAs) with polystyrene‐isoprene‐styrene (SIS) as the backbone material are widely used in transdermal drug delivery systems (TDDS) because of their high cohesive strength and drug‐carrying capacity. However, it is restricted by its high hydrophobicity when loaded with hydrophilic drugs. In this study, HMPSAs with amphiphilic properties were created by mixing SIS with fatty alcohol polyoxyethylene ether (AEO‐9) and polyethylene glycol (PEG) of different molecular weights to improve the ability of HMPSAs to deliver hydrophilic drugs. The effects of different molecular weights of PEG on the hydrophilicity of HMPSAs were also investigated. Additionally, gardenia glycosides and oleanolic acid were selected for drug release experiments. Compared to untreated HMPSAs, HMPSAs modified with AEO‐9 and PEG2000 could convert from hydrophobic to hydrophilic. The contact angle could be reduced from 91.8 to 25.6°, and the 24‐hour water absorption could be raised by 170%. The drug release experiments demonstrate that SIS/AEO‐9/PEG2000 enhances the release efficiency of the hydrophilic drug gardenia jasminoides by 69%. In summary, as a novel amphiphilic medicinal HMPSAs, SIS/AEO‐9/PEG offered a broad application promise in hydrophilic drug release.

Influence of Molecular Weight and Grafting Density of PEG on the Surface Properties of Polyurethanes and Their Effect on the Viability and Morphology of Fibroblasts and Osteoblasts.

Grafting polyethylene glycol (PEG) onto a polymer's surface is widely used to improve biocompatibility by reducing protein and cell adhesion. Although PEG is considered to be bioinert, its incorporation onto biomaterials has shown to improve cell viability depending on the amount and molecular weight (MW) used. This phenomenon was studied here by grafting PEG of three MW onto polyurethane (PU) substrata at three molar concentrations to assess their effect on PU surface properties and on the viability of osteoblasts and fibroblasts. PEG formed a covering on the substrata which increased the hydrophilicity and surface energy of PUs. Among the results, it was observed that osteoblast viability increased for all MW and grafting densities of PEG employed compared with unmodified PU. However, fibroblast viability only increased at certain combinations of MW and grafting densities of PEG, suggesting an optimal level of these parameters. PEG grafting also promoted a more spread cell morphology than that exhibited by unmodified PU; nevertheless, cells became apoptotic-like as PEG MW and grafting density were increased. These effects on cells could be due to PEG affecting culture medium pH, which became more alkaline at higher MW and concentrations of PEG. Results support the hypothesis that surface energy of PU substrates can be tuned by controlling the MW and grafting density of PEG, but these parameters should be optimized to promote cell viability without inducing apoptotic-like behavior.