Hydroxypropylcellulose Solutions Research Articles

Enhanced forward osmosis desalination of brackish water using phase-separating ternary organic draw solutions of hydroxypropyl cellulose and propylene glycol propyl ether.

This study introduces draw solutions for application in forward osmosis (FO) processes, combining mono propylene glycol propyl ether (PGPE) with the cellulose derivative hydroxypropyl cellulose (HPC). A total of 16 unique single-solute and ternary organic draw solutions were prepared and evaluated, leading to the selection of three promising solutions for further investigation. Notably, eight of the initial organic draw solutions demonstrated osmotic pressures exceeding 2.4MPa. The dynamic viscosities of all draw solutions exhibited a significant reduction with increasing temperature. Among the investigated solutions, the 0.25HPC-3.75PGPE demonstrated the most favorable FO performance, achieving average experimental water fluxes of 11.062 and 9.852 Lm-2h-1 (LMH) against a 1g/L NaCl brackish feed solution across two FO runs. PRACTITIONER POINTS: Hydroxypropyl cellulose (HPC, MW ~100,000) was mixed with propylene glycol propyl ether (PGPE) as draw solutes for FO processes. Seven combinations of HPC and PGPE produced osmolalities greater than 1000 mOsm/kg. 0.5HPC-7.5PGPE ternary draw solution achieved experimental water fluxes of 11.062 and 9.852 LMH against 1g/L NaCl brackish feed solution. Leveraging the LCSTs of these ternary organic solutions holds promise for improved separation and regeneration processes.

Liquid crystallinity of aqueous TEMPO-oxidized hydroxypropyl cellulose solutions: effects of main-chain and side-chain substituents

Liquid crystallinity of aqueous TEMPO-oxidized hydroxypropyl cellulose solutions: effects of main-chain and side-chain substituents

3D printing of responsive chiral photonic nanostructures

Finely controlled flow forces in extrusion-based additive manufacturing can be exploited to program the self-assembly of malleable nanostructures in soft materials by integrating bottom-up design into a top-down processing approach. Here, we leverage the processing parameters offered by direct ink-writing (DIW) to reconfigure the photonic chiral nematic liquid crystalline phase in hydroxypropyl cellulose (HPC) solutions prior to deposition on the writing substrate to direct structural evolution from a particular initial condition. Moreover, we incorporate polyethylene glycol (PEG) into iridescent HPC inks to form a physically cross-linked network capable of inducing kinetic arrest of the cholesteric/chiral pitch at length scales that selectively reflect light throughout the visible spectrum. Based on thorough rheological measurements, we have found that printing the chiral inks at a shear rate where HPC molecules adopt pseudonematic state results in uniform chiral recovery following flow cessation and enhanced optical properties in the solid state. Printing chiral inks at high shear rates, on the other hand, shifts the monochromatic appearance of the extruded filaments to a highly angle-dependent state, suggesting a preferred orientation of the chiral domains. The optical response of these filaments when exposed to mechanical deformation can be used in the development of optical sensors.

Photothermal enhancement of reduced graphene oxide in hydroxypropyl cellulose for a smart-window application

The ability of hydroxypropyl cellulose (HPC)-based smart windows to dynamically regulate incident light and reduce energy consumption is of great interest. Although HPC is environmentally friendly due to its nontoxicity and biodegradability, commercial applications are limited due to its relatively high lower critical solution temperature (LCST). In this paper, reduced graphene oxide (rGO) was added to HPC solutions to enhance photothermal performance and access higher solution temperatures under sunlight illumination. For a 5-mL volume of HPC solution (0.5 wt%), each milliliter of rGO solution (0.1 mg/mL) increased the solution temperature by 3.13 °C. The tadpole-shaped fibers were hydrophilic below the LCST but became hydrophobic and tended to form net structures above the phase-change temperature. Water molecules were expelled from the web structure at the same time. Our work broadens the applications of HPC in smart windows.

Enhanced solar modulation ability of smart windows based on hydroxypropyl cellulose mixed with nonionic surfactants

Thermo-responsive smart windows have attracted considerable attention due to their solar modulation ability and energy-saving performances. Researchers focus on ionic surfactants to adjust the lower critical solution temperatures (LCSTs). However, few researchers explored the effect and mechanism of nonionic surfactants. Hydroxypropyl cellulose (HPC) is an excellent thermo-responsive candidate for smart windows due to its nontoxicity and zero energy input. Herein, the effect of nonionic surfactants on HPC optical properties was investigated. The solar spectrum transmittance was evaluated as a function of nonionic surfactant types and concentrations. The addition of polyvinylpyrrolidone (PVP) significantly improved solar modulation ability(ΔTsol). The enhancement was due to the formation of larger aggregates of HPC and PVP molecules. The optimal PVP loading was 1.5 wt%, which resulted in a 69.75% ΔTsol improvement and a 1.35 °C reduction in the LCST compared with pure HPC solution. PVP would serve as a cost-effective additive to improve HPC optical properties. Heating conditions also made contributions to HPC phase separation. The energy-saving experiment verified a 4.89 °C reduction in room temperature, which confirmed the energy-saving performance. This research explains the relationship between HPC and nonionic surfactants and extends the application of HPC to smart windows.

Thermodynamics of aggregation and modulation of Rheo-Thermal properties of hydroxypropyl cellulose by imidazolium ionic liquids

Mixtures based on cellulose derivatives/ionic liquids (ILs) are potential viscosity modifiers for enhanced oil recovery (EOR). This paper investigates the thermodynamic of monocationic imidazolium ionic liquids (1-alkyl-3-methylimidazolium bromide, CnMIMBr) aggregation with hydroxypropyl cellulose (HPC) in the dilute regime and the modulation of its rheological and thermal properties in the semi-dilute regime. The outcomes showed that binding occurs by hydrophobic interactions between the alkyl chain of ILs and hydroxypropyl group on HPC and by ion–dipole interactions, and it is driven by entropy. The addition of ILs produced a significant increase in the HPC solutions' viscosity, which depends on the concentration and alkyl chain length of the ILs (n = 10, 12, 14, 16). Moreover, the presence of ILs produces an effect salt-in delaying the HPC phase separation. These findings highlight the role of ILs on the rheological and thermal properties of HPC, opening new possibilities for the design of new complex mixtures.

Old materials, new ideas: the use of concentrated solutions of hydroxypropyl cellulose to remove an aged glossy varnish on a Seventeenth Century Dutch map

The Bonaparte Tasman Map is a hand drawn map on paper in the collection of the State Library of New South Wales (SLNSW). Before treatment, crack, creases, and folds on the map’s surface formed a unique combination of deterioration features. The complex 3D shape created by differential paper drying and a glossy varnish produced a chaotic pattern of bright highlights that obscured the cartographic and graphic ornamentation and conspired to discourage any observers interested in the map. A safe method was developed to reduce the glossy varnish. Published experimental data informed the final treatment method by providing reference flow curves and a set of viscosity control variables. The dissolution of the glossy varnish was achieved by impeding the flow of solvent from the viscous hydroxypropyl cellulose solution into the varnish with applications of 7wt% to 10wt% (1 000 000 molecular weight) through a barrier layer of porous abaca tissue. The main findings were the need for a greater hydroxypropyl cellulose concentration and molecular weight, than those generally recommended in conservation. And the relationship between polymer entangled and non-entangled state, the flow movement generated by a shear force and the subsequent controlled release of solvent molecules.

Tailoring the properties of PVA/HPC/BSA hydrogels for wound dressing applications

Physical hydrogels were obtained by successive freezing/thawing of poly(vinyl alcohol) (PVA) / hydroxypropylcellulose (HPC) solutions, adding different amounts of bovine serum albumin (BSA), in presence of reduced glutathione. The morphological and structural characteristics of networks as well as their viscoelastic properties were investigated by SEM, FTIR and rheology, respectively. Due to the interconnected porous structure (average pore size between 20.7 μm and 26.7 μm), PVA/HPC/BSA hydrogels showed excellent hydrophilicity and high swelling degree values in buffer solutions (between 1000% and 1250%). For BSA content lower than 50% in the polymer network, the hydrogels present good stability in buffer solution. In addition, the BSA based hydrogels exhibited the ability to load and release small drug molecules (neomycin trisulfate salt hydrate) at pH = 7.4. The PVA/HPC/BSA hydrogels are suitable materials for wound dressing applications.

Extensional flow of stiff‐chain polymer solutions in the semidilute regime

AbstractStiff‐chain polymers are preponderant in biology as structural components of tissue and living cells. Hence, understanding their solution behavior under different flow histories is fundamental. Here, the extensional flow under capillary breakup of isotropic semidilute solutions of stiff‐chain poly‐n‐butyl isocyanate (PBIC) and hydroxypropyl cellulose (HPC) has been studied. PBIC‐chloroform and HPC‐water were studied as the polymer‐solvent interaction tunes the molecular conformation (Romo‐Uribe, J. Appl. Polym. Sci. 2021, 138, e49712). PBIC in chloroform exhibits a rod‐like conformation, and capillary breakup at constant concentration and temperature initially showed an exponential decay of filament diameter D(t) followed by a sudden decrease of D, and finally slow filament thinning. Increasing the molecular weight by threefold increased the breakup time τb by twofold. HPC in water adopts a semiflexible conformation and the filament thinning also exhibited three stages, however the breakup time was shorter than PBIC. Hence, the extensional viscosity as a function of strain of PBIC and HPC solutions exhibited three regimes, where initial constant extensional viscosity ηE was followed by strain hardening and finally a sudden decrease of extensional viscosity as strain increased. It was found that the filament breakup time τb is a function of the radius of gyration Rg.

Mechanochromic, Structurally Colored, and Edible Hydrogels Prepared from Hydroxypropyl Cellulose and Gelatin.

Hydroxypropyl cellulose (HPC) is an edible, cost-effective and widely used derivative of cellulose. Under lyotropic conditions in water, HPC forms a photonic, liquid crystalline mesophase with an exceptional mechanochromic response. However, due to insufficient physical cross-linking photonic HPC can flow freely as a viscous liquid, preventing the exploitation of this mechanochromic material in the absence of any external encapsulation or structural confinement. Here this challenge is addressed by mixing HPC and gelatin in water to form a self-supporting, viscoelastic, and edible supramolecular photonic hydrogel. It is demonstrated that the structural coloration, mechanochromism and non-Newtonian shear-thinning behavior of the lyotropic HPC solutions can all be retained into the gel state. Moreover, the rigidity of the HPC-gel provides a 69% shorter mechanochromic relaxation time back to its initial color when compared to the liquid HPC-water only system, broadening the dynamic color range of HPC by approximately 2.5× in response to a compressive pressure. Finally, the ability to formulate the HPC-gels in a scalable fashion from only water and "food-grade" constituents unlocks a wide range of potential applications, from response-tunable mechanochromic materials and colorant-free food decoration, to short-term sensors in, for example, biodegradable "smart labels" for food packaging.

Aggregation of Water Molecules to Phospholipid Head Groups Accompanied with Separation into Water‐ and Polysaccharide‐Rich Phases in Water‐in‐Oil Emulsions

AbstractMost organelles, such as the endoplasmic reticulum, are enclosed by biological membranes, although there are some membrane‐less organelles, such as stress granules. The mechanisms by which membrane‐less organelles form and keep their shape are akin to phase separation. Such organelles are located inside cell membranes. However, interactions between cell membranes, phase separations in polymer solutions and lipid head groups, directed towards the inside of the cell have not been investigated. Here we directly observed aqueous hydroxypropyl cellulose (HPC) droplets coated with lipids in mineral oil during an increase in temperature from 10 °C to 65 °C to elucidate the effect of lipid head groups located at the interfaces on dynamic phase behaviours of HPC solutions encapsulated in the cell‐sized droplets. The water molecules inside the droplets are aggregated to the interfaces during an increase in temperature due to the effect of lipid head groups with the separation into water‐ and HPC‐rich phases.

Nanocellulose-containing cellulose ether composite films prepared from aqueous mixtures by casting and drying method

A TEMPO-oxidized cellulose nanofibril (TEMPO-CNF)/water dispersion was mixed with an aqueous solution of hydroxypropyl cellulose (HPC), hydroxyethyl cellulose (HEC), methyl cellulose (MC), or carboxymethyl cellulose sodium salt (CMC). The mixtures were converted into TEMPO-CNF/cellulose ether composite films containing 0–5% TEMPO-CNFs by casting and drying of the aqueous mixtures. All the composite films had high light transparency. However, the tensile properties of the composite films of a given TEMPO-CNF content differed for the HPC and HEC, MC, and CMC matrices. The nano-reinforcing effect owing to TEMPO-CNFs was evident in the TEMPO-CNF/HPC composite films, which became strong but brittle. In contrast, the TEMPO-CNF/HEC composite films did not exhibit this nano-reinforcing effect. Transmission electron microscopy observation of the film cross-sections revealed that the TEMPO-CNF elements were homogeneously distributed in the 5% TEMPO-CNF/HPC composite film. In contrast, the TEMPO-CNF elements were densely present on the top and bottom surfaces of the 5% TEMPO-CNF/HEC composite film; the TEMPO-CNFs were heterogeneously distributed in the HEC matrix. The low gelation or aggregation concentrations of TEMPO-CNFs in water may have resulted in the different distribution states of TEMPO-CNFs, depending on the cellulose ether matrix used, and hence the different tensile behaviors.

Phase separation dynamics in aqueous solutions of thermoresponsive polymers

Phase transition kinetics of aqueous hydroxypropyl cellulose solution was studied by using turbidimetric monitoring and mathematical modelling techniques. Based on the nonlinear Cahn-Hilliard equation with a mobility depending on the component concentration, the phase separation has been modeled on a simple one-dimensional Flory lattice. For value set of the interfacial energy parameter, data were obtained on the changing of the average values of the cluster sizes, their mass and concentration. The simulation results allow us to distinguish three stages of the spinodal decomposition: early, intermediate and final. It was found that for the intermediate stage, the kinetics of the cluster mass growth is described by a dependence that is characteristic of the usual diffusion mass transfer; the change in the average cluster size can be represented by a scaling function with an exponent close to 1/3, typical of the systems with a conserved scalar order parameter. It is shown that the concentration of clusters at the final stage is determined by the temperature dependence of the interfacial energy.

Drug release from hydroxypropylcellulose gels cannot be statistically predicted from their viscometric and initial viscoelastic properties

This study questioned whether rheological properties can predict drug (metronidazole) release from Hydroxypropylcellulose (HPC) platforms. Viscometric and viscoelastic properties of aqueous, alcohols/diols and mixed solvent HPC solutions and gels were determined using viscometry and oscillatory analysis. Drug release was conducted at pH 7.4 under sink conditions. Relationships between rheological parameters and drug release were modelled using multiple linear stepwise regression. Viscometry identified ethanol and water as good solvents for HPC. Diol solvents were predicted to exhibit greater interactions with HPC (COSMO modelling) but possessed lowest intrinsic viscosities. Pentanediol or ethylene glycol prepared gels exhibited greatest elasticity. No relationships were observed between dilute solution properties and initial gel viscoelasticity. Drug release from HPC gels occurred via gel erosion and diffusion. No relationships were observed between initial gel viscoelasticity and drug release and thus, for gel platforms that undergo erosion in aqueous media, drug release cannot be predicted from initial gel viscoelasticity.

Development of Electrospun Shellac and Hydroxypropyl Cellulose Blended Nanofibers for Drug Carrier Application

The aim of this study was to develop the electrospun shellac (SHL) and hydroxypropyl cellulose (HPC) blended nanofibers for drug carrier application. The effects of polymer solution and electrospinning parameters, including SHL-HPC ratio, HPC concentration, applied voltage and flow rate, on the appearance of fibers were investigated. Based on the results, electrospun fiber was not obtained when a solution of HPC alone was employed. However, the fibers would be obviously fabricated as SHL was added to the HPC solution. An increase in the SHL ratio in SHL-HPC blended solution could accordingly lead to a remarkable enhance in the fiber diameter. In addition, the continuous nanofibers with less beads were gradually formulated when the HPC concentration was increased. The electrospinning parameters seemed to be significant. The elevation of infusion rate from 0.5 to 1 mL/h would contribute to the preparation of thick fibers with the diameters enlarging from 666.9 to 843.5 nm. With the applied voltage increasing from 15 to 30 kV during the electrospinning process, the fabrication of small nanofibers with the diameters reducing from 843.5 to 741.6 nm would be conducted. In this study, monolaurin (ML), a broad antimicrobial agent, was encapsulated into the SHL-HPC carrier for the purpose of drug delivery application. Regarding the result, the loaded concentration of ML could not be enhanced by introducing HPC to the SHL fibers.

Lignin in Bio-Based Liquid Crystalline Network Material with Potential for Direct Ink Writing.

The flow-induced supramolecular arrangement, or band texture, present in water-soluble anisotropic films prepared from blend solutions of hydroxypropyl cellulose and organosolv lignin is locked via esterification with bio-based polycarboxylic acids. Subsequent to shear casting of the blend solutions, the chemical cross-linking with citric acid-based cross-linkers and a dimerized fatty acid yields water-insoluble, anisotropic films prone to swelling in water. The liquid crystalline networks are analyzed by means of polarized optical microscopy, tensile testing, Fourier transform infrared, and swelling experiments. Depending on the cross-linker, the dry "banded" films reach up to 3.5 GPa in tensile modulus, 80 MPa in tensile strength along the shear direction, and 5 MJ/m3 toughness across the shear direction. Films are softened upon water uptake causing a reversible extinguishment of the banded texture without interfering with the specimens' anisotropy. Rheological studies point to the applicability of highly concentrated blend solutions to direct ink writing. The implementation of the findings to the additive manufacturing of cross-linked 3D structures demonstrates the potential of a resource-friendly processing of fully bio-based materials.

Influence of Aqueous Solubility-Enhancing Excipients on the Microstructural Characteristics of Furosemide-Loaded Electrospun Nanofibers.

Electrospun nanofibers were prepared from furosemide-containing hydroxypropyl cellulose and poly(vinylpyrrolidone) aqueous solutions using different solubility enhancers. In one case, a solubilizer, triethanolamine, was applied, while in the other case a pH-modifier, sodium hydroxide, was applied. Scanning electron microscopy (SEM) was carried out for morphological characterization of the fibers. The SEM images indicated similar mean diameter size of the two fibrous formulations. However, in contrast to the NaOH-containing fibers of normal diameter distribution, the triethanolamine-containing fibers showed approximately normal diameter distribution, possibly due to their plasticizing effect and the consequent slightly ribbon-like morphology. Attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), powder X-ray diffraction (XRD) and positron annihilation lifetime spectroscopy (PALS) were applied for microstructural characterization. The FTIR measurements confirmed that furosemide salt was formed in both cases. There was no sign of any crystallinity based on the XRD measurements. However, the PALS highlighted the differences in the average o-Ps lifetime values and distributions of the furosemide-loaded fibrous formulations. The two types of electrospun nanofibrous formulations containing amorphous furosemide salt showed similar macrostructures but different microstructural characteristics depending on the type of solubility enhancers, which lead to altered storage stability.

The Formation and Elasticity of a Hydroxypropyl Cellulose Film at a Water–Air Interface

The kinetics of spreading of aqueous hydroxypropyl cellulose (HPC) solutions with different concentrations over a water surface and the rheological properties of films formed at the water–air interface have been studied. The performed experiments are distinguished by the fact that the solvent in the polymer solutions is identical to the liquid subphase, while, beginning from a certain concentration, the aqueous HPC solutions are capable of forming a liquid-crystalline phase. The chosen initial polymer solution concentrations correspond to different regions of the phase diagram for the HPC–water system. The contact of a solution droplet with water yields a time-stable spot of an HPC solution layer. In spite of the fact that some solution concentrations correspond to the existence range of a lyotropic liquid-crystalline phase, an isotropic layer is formed on the water surface irrespective of the concentration and phase state of the solution in the droplet. The dynamic dilatational storage modulus of such an interfacial layer at a frequency of 0.03 Hz is equal to 43 ± 2 mN/m; i.e., it almost coincides with the surface tension of the formed interfacial layer.

The Structure of Polymer Clusters in Aqueous Solutions of Hydroxypropyl Cellulose

The viscosity, turbidity, and heat capacity of dilute aqueous solutions of hydroxypropyl cellulose have been studied in a concentration interval of 0.047–1.5 g/l and a temperature interval of 20–80 ∘C. The data obtained testify that, if the temperature does not exceed 40 ∘C, hydroxypropyl cellulose molecules are prolate spheroidal globules with semiaxis lengths of 7 and 490 ˚ A. At temperatures above 70 ∘C, the hydroxypropyl cellulose solution consists of clusters; every cluster is composed of 11 globules and has a prolate spheroidal form with semiaxes of 41 and 490 ˚ A. In the temperature interval from 40 to 70 ∘C, the solution concerned contains both globules and clusters, with the concentration of the latter increasing, as the temperature grows.

Optimization of Nasal Drug Absorption from Powder Formulations: The Feasibility of Controlling Drug Absorption by the Use of Pharmaceutical Excipients

Nasal application of powder formulations has garnered attention because of its significant potential for systemic drug delivery. Because a powder drug must first diffuse from the formulation and dissolve in the nasal cavity fluid before transepithelial permeation, dissolution and diffusion are distinct but important factors for nasal drug absorption. Since the formulation is directly administered onto the nasal mucosal surface, the effect of excipients on drug absorption may be significant. Therefore, the influence of excipients on nasal drug absorption was evaluated. Three types of hydroxypropyl cellulose (HPC) [HPC (SL), HPC (M), and HPC (H)], lactose, and sodium chloride (NaCl) were used as excipients. Warfarin (WF), piroxicam (PXC), sumatriptan (STP), and norfloxacin (NFX) were selected as model drugs. HPC (M) enhanced the absorption of PXC, while both HPC (M) and HPC (H) enhanced the absorption of STP. All three HPCs failed to enhance the absorption of WF. An increase in the polymerization degree of HPCs decreased the diffusion of drugs in HPC solutions, but prolonged their nasal retention. Lactose and NaCl increased the fluid volume on the nasal mucosal surface by increasing the osmotic pressure, thereby enhancing the nasal absorption of PXC and NFX; however, lactose and NaCl accelerated the nasal clearance of these. These results indicate that nasal drug absorption from powder formulations can be controlled by excipients.