PEO Block Research Articles

Quest for Thermoresponsive Block Copolymer Nanoparticles with Liquid-Crystalline Surfactant Cores.

This work reports on the preparation and characterization of anisotropic composition nanoparticles based on the electrostatic binding of dodecyltrimethylammonium surfactant to poly(acrylic acid) blocks of diblock copolymers with poly(ethylene oxide) (PEO) and poly(N-isopropyl acrylamide) (PNIPAm). These nanoparticles form kinetically stable dispersions and display liquid–crystalline cores with a micellar cubic structure, as determined by small-angle X-ray scattering. Mixtures with different proportions of the two block copolymers and stoichiometric amounts of C12TA+ were prepared and their behavior was compared with that of the parent nanoparticles. Upon heating, dilute dispersions (0.01 and 0.1 wt %) analyzed by dynamic light scattering display a slight decrease in the hydrodynamic radius, consistent with the dehydration of PNIPAm and mixed PNIPAm–PEO blocks at the shell. At higher concentrations, 2 wt %, the nanoparticles with pure PNIPAm shell undergo macroscopic phase separation above 32 °C. Nanoparticles with a pure PEO shell do not display temperature sensitivity. For the mixtures, no visual change is observed, but the dynamic light scattering results evidence the formation of clusters, whose size and reversibility depend on the PEO/PNIPAm proportion. This indicates the formation of mixed nanoparticles containing both PEO and PNIPAm blocks. Nuclear Overhauser enhancement spectroscopy NMR analyses of the mixtures do not show the correlation peak expected for PEO and PNIPAm blocks in close proximity, suggesting their segregation at the nanoparticle shell. On the basis of these results, we discuss the possibilities of the neutral blocks distribution on the shell of mixed nanoparticles. Overall, we have confirmed that these nanoparticles may display a temperature-controlled reversible aggregation while preserving their internal liquid–crystalline structures.

Antifouling ultrafiltration membranes by selective swelling of polystyrene/poly(ethylene oxide) block copolymers

Ultrafiltration (UF) membranes with high permeability and good fouling resistance hold great promise in water treatment and many industry sectors. Herein, antifouling UF composite membranes with mesoporous films of polystyrene (PS)/poly(ethylene oxide) (PEO) block copolymer as the selective layers were produced by the process of selective-swelling-induced pore generation. We spin-coated thin layers of block copolymer onto macroporous supports, and activated the copolymer layers by soaking them in hot ethanol to induce the selective swelling of the PEO microdomains. The porous structures of the block copolymer selective layers can be continuously modulated simply by varying the swelling durations, resulting in UF membranes with water permeabilities adjustable in the range of ~ 100 to 600Lm-2h-1bar-1. Interestingly, the hydrophilic PEO blocks were enriched on the pore walls after swelling, rendering an inherent fouling resistance to the membranes. Protein fouling tests demonstrated that the membrane exhibited exceptional fouling resistance with a recover ratio in water flux of nearly 100%. This fouling resistance is expected to be long-standing as the PEO chains are covalently bonded to the membrane matrix.

Enhanced conductivity of polyaniline in the presence of nonionic amphiphilic polymers and their diverse morphologies

ABSTRACTPoly(ethylene oxide) (PEO) and its copolymers have excellent affinity for protons and contribute to proton transfer. In the present study, PEO and its copolymers, poly[(ethylene oxide)20‐(propylene oxide)70‐(ethylene oxide)20] (EO20PO70EO20, P123) and poly[(ethylene oxide)106‐(propylene oxide)70‐(ethylene oxide)106] (EO106PO70EO106, F127), have been found to significantly enhance the conductivity of polyaniline (PANI). After introducing these polymers, the conductivity of PANI is markedly promoted more than two orders of magnitude compared to that of PANI without additives, from 5.2 to 667 S/m. The molecular weight of PEO affects the conductivity of PANI/PEO. The mechanism by which these amphiphilic polymers are beneficial to the conductivity of PANI is studied experimentally and theoretically. The PANI/P123 prepared in the presence of PEO block copolymer shows gradually varying morphologies containing leaflike sheets, rodlike particles, and uniform chestnutlike sphere particles. This is similar to the morphology change of micelles with surfactant concentration. PEO, P123, and F127 are further found to have a positive effect on PANI as a material for sensors or supercapacitors, since high specific capacity and fast response rate are desired qualities in sensors and supercapacitors. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45547.

Development of propolis-loaded block copolymer micelles of superior structural stability and high loading capacity

We report on the efficient loading of poplar propolis into core-shell micelles based on amphiphilic poly(ethylene oxide)-block-poly(n-butyl acrylate) (PEO-b-PnBA) diblock copolymers. The copolymers comprising a hydrophilic PEO block of constant length (113 monomer units) and a soft hydrophobic PnBA block of three different lengths (53, 99 and157 monomer units) were synthesized by atom transfer radical polymerization (ATRP) of n-butyl acrylate initiated by PEO bromoisobutyrate. The study focused on fabrication of stable aqueous colloid systems characterized by complete encapsulation of all bioactive lipophilic propolis constituents with in the micellar carrier. The effects of copolymer/propolis mass ratio, copolymer composition and concentration on system characteristics were examined by dynamic light scattering (DLS), atomic force microscopy (AFM) and turbidity measurements. The results revealed that stable aqueous colloids and complete encapsulation of the lipophilic bioactive compounds into the micelles can be achieved at twofold excess of copolymer to propolis amount.

Increase in the length of poly(ethylene oxide) blocks in amphiphilic copolymers facilitates their cellular uptake

ABSTRACTAmphiphilic nonionic block copolymers induce different biological effects on living cells. In particular, the hydrophobic members of the Pluronics family suppress drug efflux systems in multidrug‐resistant cells, whereas hydrophilic Pluronics support cell viability. However, the relationship between the copolymer structure and its binding to cells is still unclear. Using a tritium‐labeling approach, we analyzed interactions of nine Pluronics and three diblock copolymers with human and murine cells in vitro and revealed that the binding efficiency of the copolymers increased in line with the length of their poly(ethylene oxide) (PEO) blocks. In contrast, partitioning of the same polymers into artificial lipid bilayers determined by Isothermal Titration Calorimetry (ITC) decreased with increasing length of the PEO block. The opposite influence of hydrophilic blocks on the copolymer affinity to living cells and artificial lipid bilayers implied the binding of long PEO blocks to the hydrophilic moieties of cellular membranes. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45492.

Composition and properties of complexes between anionic liposomes and diblock copolymers with cationic and poly(ethylene oxide) blocks

A series of cationic diblock copolymers were synthesized via sequential anionic polymerization of 2-vinylpyridine and ethylene oxide and further quaternization of the resulting diblock copolymers with dimethyl sulfate. Diblock copolymers with a degree of polymerization (DP) of the cationic block equal to 40 and DP of the poly(ethylene oxide) (PEO) block equal to 45, 210 and 450, as well as a cationic homopolymer with DP = 40 (control), were adsorbed on the surface of anionic liposomes of 40–60 nm in diameter. The liposomes were constructed with egg lecithin admixed with 0.1 mole fraction of a doubly anionic lipid, cardiolipin. The liposome–polymer complexes were characterized using electrophoretic mobility measurements, dynamic light scattering, conductivity, fluorescence and UV spectroscopy, and differential scanning calorimetry. Adsorption of the polymers causes the liposomes to aggregate; the only exception is the diblock copolymer with DP of the PEO block of 450, which shows an aggregation-preventing effect. In all cases, the integrity of liposomes is retained upon their complexation with polymers. The diblock copolymer with a short PEO block induces clustering of anionic lipid in the outer leaflet of the membrane; this effect becomes less pronounced with increasing DP of the PEO block. The differences in behaviour of the diblock copolymers are explained in terms of copolymer cluster formation via hydrogen bonding between neighbouring PEO blocks. These observations are important for interpretation of biological effects produced by cationic polymers and selection of cationic polymers for biomedical applications. © 2017 Society of Chemical Industry

Thermoresponsive behavior of block copolymers of PEO and PNIPAm with different architecture in aqueous solutions: A study by NMR, FTIR, DSC and quantum-chemical calculations

Temperature behavior of D2O solutions of thermoresponsive diblock poly(ethylene oxide) (PEO)-b-poly(N-isopropylacrylamide) (PNIPAm) copolymers and Y-shape triblock PEO-b-(PNIPAm)2 copolymers was investigated and compared with the phase transition of the PNIPAm homopolymer by combination of NMR and ATR FTIR spectroscopy, DSC and model quantum-chemical calculations. It is shown that the phase transition and structures of PNIPAm component (forming micellar cores) are significantly affected not only by the presence of the PEO block but also by copolymer architecture. Both these factors affect energetics of the phase transition, influence of the polymer concentration and behavior of bound water at elevated temperatures. They also affect the degree of dehydration of PNIPAm segments (CO groups) at temperatures above the phase transition which is higher for block copolymers (especially for the diblock) in comparison with PNIPAm homopolymer. NOESY NMR spectra likewise revealed influence of the architecture of the block copolymer on its conformational behavior in the pretransition region.

Spherical Compound Micelles with Lamellar Stripes Self‐Assembled from Star Liquid Crystalline Diblock Copolymers in Solution

Detailed investigations on the self‐assembly of amphiphilic star block copolymers composed of three‐arm poly(ethylene oxide) (PEO) and poly(methacrylate) (PMAAz) with an azobenzene side chain (denoted as 3PEO‐b‐PMAAz) into stable spherical aggregates with clear lamellar stripes in solution are demonstrated. Four block copolymers, 3PEO12‐b‐PMA(Az)33, 3PEO22‐b‐PMA(Az)31, 3PEO22‐b‐PMA(Az)62, and linear PEO68‐b‐PMA(Az)31, are synthesized. The liquid crystalline properties of the block copolymers are studied by differential scanning calorimetry, polarized optical microscopy techniques, and wide‐angle X‐ray diffraction. The morphologies of the compound micelles self‐assembled in tetrahydrofuran (THF)/water mixtures are observed by means of transmission electron microscopy and scanning electron microscopy. The size of the spherical micelles is influenced by the self‐assembly conditions and the lengths of two blocks. The well‐defined three‐arm architecture of the hydrophilic blocks is a key structural element to the formation of stable spherical compound micelles. The micelle surface integrity is affected by the lengths of PEO blocks. The lamellar stripes are clearly observed on these micelles. This work provides a promising strategy to prepare functional stable spherical compound micelles self‐assembled by amphiphilic block copolymers in solution.

PE-b-PEO block copolymer nanostructured thermosetting systems as template for TiO2 nanoparticles

Two different, molecular weight and blocks ratio, poly(ethylene-b-ethylene oxide) block copolymers (PE-b-PEO) were used as nanostructuration agent for epoxy based thermosets and as surfactant for sol-gel synthesized titanium dioxide (TiO2) nanoparticles. Obtained DSC results confirmed the miscibility of PEO block of PE-b-PEO block copolymer with epoxy monomer in PE-b-PEO/DGEBA unreactive mixtures and with DGEBA/MCDEA matrix in cured systems modified with PE-b-PEO block copolymer without or with TiO2 nanoparticles. The dilution effect caused by the addition of PE-b-PEO block copolymer on the epoxy/amine reaction mixture was verified.AFM phase images proved that nanostructured thermosetting systems can be reached in function of PE-b-PEO block copolymer content. Good dispersion and, in the case of the cured systems modified with higher molecular weight and higher PEO content PE-b-PEO block copolymer, selective localization of TiO2 nanoparticles can be achieved. The morphology of investigated thermosetting systems and the good dispersion of TiO2 nanoparticles depend on the PEO block content in PE-b-PEO block copolymer and its molecular weight.Transparent PE-b-PEO block copolymer nanostructured thermosetting systems with hydrophilic character and well dispersed or positioned TiO2 nanoparticles can be obtained.

Complexing P2VP and P2VP-b-PEO with Wedge-Shaped Amphiphiles

We report on the structure of a system of wedge-shaped molecules with a sulfonic end group incorporated into the both the homopolymer P2VP and the block copolymer P2VP-b-PEO, at degrees of complexing of 25%, 50%, and 100%. From X-ray scattering in the bulk all three homopolymer complexes reveal a lamellar phase, which is, however, for 100% mixed with a hexagonal phase. In agreement with earlier work on thin films, the corresponding block copolymers show all a structure of PEO cylinders perpendicular to lamellae of the ligands. Between 25% and 50% neutralization the packing changes from relatively loose layers consisting of several backbone chains with ligands for 25% to a situation of single backbones with highly stretched ligands for higher degrees of neutralization. In the latter cases crystallization of the confined PEO blocks is strongly reduced.

Multiscale Simulations of Lamellar PS–PEO Block Copolymers Doped with LiPF6 Ions

We report the results of atomistic simulations of the structural equilibrium properties of PS–PEO block copolymer (BCP) melt in the ordered lamellar phase doped with LiPF6 salt. A hybrid simulation strategy, consisting of steps of coarse-graining and inverse coarse-graining, was employed to equilibrate the melt at an atomistic resolution in the ordered phase. We characterize the structural distributions between different atoms/ions and compare the features arising in BCPs against the corresponding behavior in PEO homopolymers for different salt concentrations. In addition, the local structural distributions are characterized in the lamellar phase as a function of distance from the interface. The cation–anion radial distribution functions (RDF) display stronger coordination in the block copolymer melts at high salt concentrations, whereas the trends are reversed for low salt concentrations. Radial distribution functions isolated in the PEO and PS domains demonstrate that the stronger coordination seen in B...

Adjusting the size of multicompartmental containers made of anionic liposomes and polycations by introducing branching and PEO moieties

We propose a strategy to adjust the size of multiliposomal complexes made of small unilamellar anionic liposomes (lipid bilayer vesicles prepared from zwitterionic lipid 1,2-dioleoyl-sn-glycero-3-phosphocholine DOPC and ionic lipid 1-palmitoyl-2-oleoyl-sn-glycero-3-phospho-l-serine POPS with a typical diameter of 50 nm) with cationic polymers due to electrostatic attraction. Hereby, the use of quaternized poly(dimethylaminoethyl methacrylate), qPDMAEMA, allows the construction of multicompartmental carriers. Variation of the architecture and composition of various qPDMAEMA samples demonstrates the effect of introducing poly(ethylene oxide) PEO moieties and/or branching on the size of the hierarchical assemblies: both the PEO block (as seen for block copolymers and miktoarm stars) and the branching (as seen for star-shaped homopolymers and miktoarm stars) lead to smaller complexes compared to complexes with a linear qPDMAEMA homopolymer. Besides the use of cryogenic transmission electron microscopy (cryo-TEM), the formation of multicompartmental carriers composed of differently loaded liposomes is verified by two-color fluorescence cross-correlation spectroscopy (FCCS).

Adsorption of non-ionic ABC triblock copolymers: Surface modification of TiO2 suspensions in aqueous and non-aqueous medium

A series of non-ionic ABC triblock copolymers, such as poly(butadiene)-b-poly(2-vinylpyrridine)-b-poly(ethylene oxide) (PB-P2VP-PEO) were synthesized by sequential anionic polymerizations. For these copolymers comprising an organo-soluble PB and a water-soluble PEO block, their P2VP middle block has been selected for its anchoring capacity on solid surfaces. The adsorption isotherms on TiO2 were obtained in heptane and in aqueous medium, as selective solvents. In both of these cases, the P2VP middle block provides the surface anchoring, whereas PB and PEO sequences are acting as stabilizing moieties in heptane and water respectively. By extension to ABC triblock copolymers of the scaling theory developed for diblock copolymers, the density of adsorbed chains could be correlated with the molecular characteristics of the PB-P2VP-PEO triblock copolymers. From a practical point a view, it could be demonstrated that these copolymers are efficient dispersing agents for the TiO2 pigments in both aqueous and non-aqueous medium.

A novel type of responsive double hydrophilic block copolymer-based multifunctional fluorescence chemosensor and its application in biological samples

In this paper, a novel type of responsive double hydrophilic block copolymer (DHBC)-based multifunctional chemosensors to Al3+, Zn2+ and temperature was designed and prepared. The well-defined DHBCs with Al3+ and Zn2+-reactive thermosensitive block (copolymer fluorescence chemosensor), poly(ethylene oxide)-b-poly(N-isopropylacrylamide-co-SHMA)65(PEO113-b-P(NIPAM-co-SHMA)65, Mn=13.2kDa,Mw/Mn=1.09), were synthetized by reversible addition-fragmentation chain transfer (RAFT) polymerization. The novel well water-soluble copolymer fluorescence chemosensor could selectively recognize Al3+ (blue fluorescence) and Zn2+ (green fluorescence) by the difference of the fluorescence color. Moreover, this copolymer fluorescence chemosensor has the ability to selective recognition Al3+ or Zn2+ in their mixed solution by controlling the fluorescence response time. The detection limit of 0.1g/L copolymer fluorescence chemosensor for the analysis of Al3+ and Zn2+ ions at 25°C were calculated to be ∼5.23 and ∼11.99ppb, respectively. PEO113-b-P(NIPAM-co-SHMA) can self-assemble into micelles with P(NIPAM-co-SHMA) block as core and well-solvated PEO block as coronas when heating to the lower critical solution temperature (LCST), and the detection limit of Al3+ and Zn2+ ions at 40°C can be decreased to ∼2.14 and ∼8.71ppb, respectively. Furthermore, the copolymer fluorescence chemosensor has been successfully applied to detect Al3+ and Zn2+ in biological samples.

Synthesis and Self-Assembly of a Series of nPOSS-b-PEO Block Copolymers with Varying Shape Anisotropy

Manipulation of shape anisotropy of building blocks is creating diverse and complex assemblies, in particular in the field of colloid science. Self-assembly of block copolymers has created a great number of nano-objects and/or nanostructures. Herein we report the design and synthesis of a series of block copolymers with varying shape anisotropy using polyhedral oligomeric silsesquioxane (POSS) cluster and linear poly(ethylene oxide)s (PEO) with different molecular weights. The POSS-b-PEO block copolymers were prepared by means of first gathering one to four POSS clusters using short linear or dendritic linkers and then covalently linking them with linear PEO blocks. In this way, the shape anisotropy of the POSS-b-PEO block copolymers is varied widely. We found that the PEO block crystallization in a selected solvent drives the block copolymers to self-assemble into large nanothick sheets. We characterized the sheets using TEM and XRD and found a structure of one PEO crystalline layer sandwiched by two POS...

High concentration exfoliation of graphene in ethyl alcohol using block copolymer surfactant and its influence on properties of epoxy nanocomposites

ABSTRACTIn this work, high concentration exfoliation (∼0.2 mg/ml) of graphene in ethyl alcohol is achieved in presence of block copolymer of polyethylene oxide–polypropylene oxide–polyethylene oxide (PEO–PPO–PEO) using sonication followed by centrifugation. The obtained graphene solution is used to prepare epoxy nanocomposites. Flexural tests were conducted over epoxy nanocomposites. The 0.018 wt% of PEO–PPO–PEO block copolymer exfoliated graphene in epoxy matrix shows 21.7% and 15.8% enhancement in flexural modulus and flexural strength respectively as compared to pure epoxy. Transmission electron microscopy reveals well dispersion of graphene in epoxy matrix; and fractography of flexural fractured sample shows graphene dispersion restricts the crack propagation. The well-dispersed graphene in epoxy matrix increase the dielectric constant and thermal stability of epoxy nanocomposites. Further, the enhanced graphene dispersion in epoxy nanocomposites reduces the glass transition temperature (Tg). Thus, enhanced mechanical properties achieved by dispersion of block copolymer exfoliated graphene in epoxy nanocomposites make it suitable for several applications.

Polyurethanes containing Poly(arylene ether sulfone) and Poly(ethylene oxide) segments for gas separation membranes

Poly(arylene ether sulfone) and poly(ethylene oxide) (PEO)-based segmented polyurethanes were synthesized as potential gas separation membrane materials. Poly(arylene ether sulfone) oligomers with controlled molecular weights (15,000 and 20,000 g/mol Mn) were prepared with phenol endgroups by nucleophilic aromatic substitution step growth polymerization of 4,4'-dichlorodiphenylsulfone with a calculated excess of 4,4'-(propane-2,2-diyl)diphenol (bisphenol A). The oligomers with phenolic endgroups were subsequently reacted with ethylene carbonate to obtain aliphatic hydroxyethyl terminal functionality. The hydroxyethyl terminated polysulfone oligomers and hydroxy-terminated PEO were reacted with 4,4'-methylene diphenyl diisocyanate (MDI) to obtain segmented polyurethanes. Compositions with high poly(arylene ether sulfone) content relative to the hydrophilic PEO blocks were of particular interest due to their mechanical integrity. Size exclusion chromatograms confirmed that the polyurethanes had high molecular weights with unimodal molecular weight distributions. DMA and DSC thermograms revealed polyurethanes containing 30 wt % PEO have two distinct Tg's. Pure gas permeabilities of membranes were measured using a series of gases having different kinetic diameters including H2, He, CO2, O2, N2, and CH4. Gas transport measurements showed changes in permeabilities as the PEO content in the polyurethane increased. The CO2/N2 and CO2/CH4 gas selectivity of membranes increased systematically as PEO content increased in the polyurethanes.

PEE–PEO Block Copolymer Exchange Rate between Mixed Micelles Is Detergent and Temperature Activated

We examine the kinetics of polymer chain exchange between mixed block copolymer–detergent micelles, a system relevant to the synthesis of protein-containing biomimetic membranes. While chain exchange between block copolymer (BCP) aggregates in water is too slow to observe, and detergent molecules exchange between micelles on a time scale of nanoseconds to microseconds, BCP chains exchange between mixed detergent–polymer micelles on intermediate time scales of many minutes to a few days. We examine a membrane-protein-relevant, vesicle-forming, ultrashort polymer, poly(ethyl ethylene)20-poly(ethylene oxide)18 (PEE20–PEO18). PEE20–PEO18 was solubilized in mixed micelles with the membrane protein compatible nonionic detergent octyl-β-d-glucoside (OG). Using cryo-TEM and small-angle neutron scattering (SANS), we demonstrate complete solubilization of the polymer into micelles. Using time-resolved SANS (TR-SANS), we provide the first direct evidence that detergents activate BCP chain exchange and determine kine...

Organocatalyzed ring‐opening polymerization of cyclic butylene terephthalate oligomers

ABSTRACTIn this study, various organic compounds, with different activation modes, have been tested as catalysts for the ring‐opening polymerization (ROP) of cyclic butylene terephthalate oligomers (CBT) in bulk at 210 °C, using tert‐butylbenzyl alcohol (tBnOH) as initiator. Among them, 1,3,5‐triazabicyclo[4.4.0]dec‐5‐ene (TBD) appeared to be the most efficient, achieving high monomer conversions in short reaction times (within minutes). Analysis by size‐exclusion chromatography (SEC) of the poly(butylene terephthalate) (PBT) synthesized using this catalyst also showed that the polymerization follows the expected theoretical Mn trend for molecular weights up to 50 kg·mol−1. Chain‐end fidelity relatively to the alcohol initiator has been confirmed by MALDI‐TOF mass spectroscopy, which showed that all polymer chains possess the tert‐butylbenzyl moiety as chain‐end. Finally, to demonstrate the potential of this system for the synthesis of PBT‐based block copolymers, a monomethyl ether poly(ethylene glycol) (PEG) of 5000 g·mol−1 has been employed as initiator for the ROP of CBT. A PEO‐b‐PBT block copolymer of 15,000 g·mol−1 could thus been obtained, as confirmed by the shift of the SEC traces towards higher molecular weights and the same diffusion coefficient determined for 1H NMR signals of the PEO block and the PBT block. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017, 55, 1611–1619

Transparent nanostructured cellulose acetate films based on the self assembly of PEO-b-PPO-b-PEO block copolymer

In this study fabrication and characterization of transparent nanostructured composite films based on cellulose triacetate (CTA) and poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide) (EPE) triblock copolymer were presented. The effect of the addition of EPE triblock copolymer on the thermal stability, morphology, and mechanical properties of cellulose triacetate films was investigated. The triblock EPE was chosen since PEO blocks interact favorably with CTA, whereas, PPO blocks remain immiscible which provokes a microphase separation. This allows to obtain EPE/CTA composite films with ordered microphase-separated structures where PPO spherical microdomains are well-dispersed in PEO/CTA matrix by simple solvent-evaporation process. During this process, PEO block chains selectively interact with CTA by strong interpolymer hydrogen-bonding while PPO block microseparated. The addition even 40wt% of EPE leads to nanostructured EPE/CTA composite. The cytotoxicity assay of CTA and EPE/CTA composite films confirm non-toxic character of designed transparent nanostructured composites based on sustainable matrices.