Decrease In Transition Temperature Research Articles

Effects of High Temperature and Different Salt Solutions on Basalt Fiber-Reinforced Composites’ Bonded Joint Durability Impact

Fiber-reinforced composites are widely used in industrial development due to their excellent performance, and the study of basalt fiber-reinforced resin (BFRP) as a new type of economical and environmentally friendly material is highly valued, since harsh environments can affect the durability of bonded joints. In this paper, the Araldite® 2015 adhesive for BFRP–BFRP single lap joints (SLJs) was selected as the subject of study and the joints were analyzed in aging experiments in three environments: deionized water (DW), 3.5% NaCl solution, and 5% NaCl solution at 80 °C for 0 days (no aging), 10 days, 20 days, and 30 days. Using Fick’s second law to describe water absorption in joints and materials, the comparison shows that the water absorption in the joints occurs primarily in the adhesive. Differential scanning calorimetry (DSC) was used to characterize the decrease in the glass transition temperature (Tg) of the adhesive at each failure point, and the thermogravimetric analysis (TGA) tests showed that moisture and heat led to the degradation of the polymer material in the joint. The failure strength of the joints in quasi-static tensile tests was positively correlated with the moisture content of the solution, and the changes in the absorption peaks of the functional groups of the adhesive after aging were observed. The comprehensive macro-micro failed section analysis showed that the water molecules damage the chemical properties of the adhesive, meaning that the adhesive and BFRP binding ability is decreased. The proportion of failure section tear decreased with the extension of the aging time, and a high temperature induced water evaporation and an adhesive post-curing reaction. The change in the failure mode is a result of the combined effect of the post-curing effect and hydrolysis reaction, which is validated by the results of the Fourier infrared spectroscopy (FTIR). This study contributes to an in-depth understanding of the effect of moisture and heat on the residual properties of bonded joints.

Comprehensive study of optical, thermal, and gamma-ray shielding properties of Bi2O3–ZnO–PbO–B2O3 glasses

Abstract The Bi2O3–ZnO–PbO–B2O3 (BiZPB) glasses are prepared using the melt-quenching technique. As the concentration of lead oxide increases, the band gap energy (E g) decreases from 2.864 to 2.671 eV. The BiZPB glasses exhibit remarkable stability under thermal stress, as indicated by the thermogravimetric analysis graph, with only a marginal 0.5% loss in their initial mass. The decrease in the glass transition temperature (T g) of BiZPB glasses, with an increase in the PbO concentration, can be attributed to the specific influence of PbO on the glass structure and properties. The radiation shielding performance for the prepared glasses is evaluated using Phy-X software. The transmission factor (TF) for the 10B2O3–10ZnO–40PbO–40B2O3 glass sample is almost zero at 0.122 MeV, which means that this glass sample can attenuate almost all the photons with an energy of 0.122 MeV, whereas the TF values for this sample with thicknesses of 0.5 and 1 cm are 88 and 77%, respectively., it can be observed from the TF values that the prepared glasses have good attenuation performance against low energy (0.122, 0.245, and 0.344 MeV), while they have weak shielding performance against high energy radiation. The addition of PbO causes a reduction in TF, which means that the addition of an extra amount of PbO into the glasses results in an enhancement in the radiation shielding competence of the samples. The average half-value layer ( HVL ̅ \bar{{\rm{HVL}}} ) is also calculated. The results demonstrated that HVL ̅ \bar{{\rm{HVL}}} is at its lowest between 0.248 and 0.411 MeV, ranging between 0.396 and 0.513 cm.

Preparation and Properties of Immiscible Poly(lactic acid)/Ethyl Cellulose Bioplastic Blends with Good Transparency and Optical Control by Drawing

In this study we prepared a poly(lactic acid)/ethyl cellulose (PLA/EC) bioplastic blend film by melt pressing after solvent casting and investigated the optical, thermal, and mechanical properties in relation to the structural changes revealed by various microscopies and scattering measurements. Despite the immiscibility of PLA and EC, the blend film exhibited good optical transparency due to the close match in their refractive indices. A second run of differential scanning calorimetry during heating revealed a decrease in the glass transition temperature () and melting point () of PLA with EC although EC had the higher values. Thermomechanical analysis suggested that these decreases were due to the negative pressure generated due to the suppression of PLA shrinkage below and above during cooling. Furthermore, ductile drawing of the blend film (70/30) at an optimal temperature of 70 °C above resulted in a uniform whitening near 100% strain. Delamination at the interface between the PLA matrix and EC domain led to the formation of micrometer-sized oriented voids, which enhanced the refractive index difference in the phase-separated structure, thereby scattering light and achieving the uniform and oriented white blend film.

Effect of oxygen vacancies and cationic valence state on multiferroicity and magnetodielectric coupling in (1-x)BaTiO3.(x)LaFeO3 solid solution

A solid solution of (1-x)BaTiO3–(x)LaFeO3 (x = 0, 0.007, 0.015, 0.031, 0.062) has been investigated for room temperature multiferroicity and magnetodielectric effect. The incorporation of La and Fe ions in ferroelectric BaTiO3 leads to increased lattice disorder and generation of oxygen vacancies that induces magnetism. A detailed correlated study using XRD, XPS and Raman spectroscopy is being reported. A typical ferromagnetic and ferroelectric nature of each sample are confirmed by M−H and P–E hysteresis loops, respectively at room temperature. Temperature dependent dielectric studies reveal the decrease of transition temperature from 137 0C for undoped to room temperature for increasing substitution. The changes in the dielectric property with applied magnetic field shows the indications of magnetodielectric effect. For x = 0.015, existence of both proper ferroelectric without lossy properties and ferromagnetic properties in a single tetragonal phase makes it a perfect room temperature multiferroic material. For this sample, the magnetodielectric coupling is the strongest with Magnetocapacitance of ∼2.7% and Magneto loss of ∼0.8% at 10 kHz and 1 T. The multiferroicity and the magnetodielectric effect exhibited by this material has been correlated to the structural properties, electric and magnetic properties, changes in valence states, and oxygen vacancy (Ov).

Effect of pressure on superconductivity of LaBi3

The electronic properties, phonon properties, and conventional superconducting properties of the newly synthesized AuCu3-type intermetallic compound LaBi3 using first-principle density functional methods have been reported in this research article.Variations in conventional superconducting properties like transition temperature, electron–phonon coupling constant, Eliashberg spectral function and average logarithmic phonon frequency with applied hydrostatic pressure have been reported in this research article. At ambient pressure, the transition temperature and coupling constant was computed to be 7.2 K and 2.78 respectively. The calculated decrease in transition temperature with applied pressure as reported in this article agrees with the previously reported experimental results. Ambient pressure fermi surface was employed to explain the high electron–phonon coupling constant.

Correlations between the dopant concentration and ion transport properties of plasticized NaCMC-Pectin polyblend electrolyte membranes for electrochemical device applications

This study explores the structural and electrical properties of sodium carboxymethyl cellulose (NaCMC)–pectin (PC)–glycerol–NH4Br electrolyte films and investigates their potential applications in proton batteries. Plasticized solid polymer electrolyte (SPEs) films were fabricated using the solution casting method. The interaction between the salt and polymer blends was verified using Fourier-transform infrared (FTIR) analysis. Incorporation of various salt concentrations (up to 25 wt%) was found to enhance the amorphous phase of the polymer blend, as evidenced by X-ray diffraction (XRD) results. Additionally, the decrease in the glass transition temperature, as confirmed by DSC analysis, indicates that the inclusion of both plasticizer and salt contributed to this effect. An electrolyte with 25% wt. of NH4Br has the highest room temperature conductivity of 4.68 ×10−4 S cm−1. This electrolyte was employed to fabricate the proton battery for energy storage application.

Structure-Property Relationships of Short Chain (Mixed) Cellulose Esters Synthesized in a DMSO/TMG/CO2 Switchable Solvent System.

Increasing environmental pollution and petroleum resource depletion are important indicators for the necessary and inevitable replacement of fossil-based polymeric materials with more sustainable counterparts. Hence, the development of bio-based materials from renewable resources, such as cellulose, is of great importance. Herein, we introduce a rapid and homogeneous microwave assisted synthesis of high molecular weight (59 kDa ≤ Mn ≤ 116 kDa) short chain (mixed) cellulose esters (CEs) with variable acyl side chain length (2 ≤ C ≤ 8) by using a DMSO/TMG/CO2 switchable solvent system. Accordingly, (mixed) CEs were synthesized by implementing tetramethylguanidine (TMG) into a switchable solvent system (DMSO/TMG/CO2), followed by in-depth structural characterization via IR, 1H NMR, 13C NMR, and SEC. Examination of the structure-property relationships revealed a decrease in the glass transition temperature (177 °C ≤ Tg ≤ 204 °C), an increase in surface hydrophobicity, i.e., water contact angle (WCA) (65° ≤ WCA ≤ 98°), and a decrease of Young's modulus (7.51 MPa ≤ E ≤ 13.6 MPa), with longer alkyl side chains.

Effect of iodine on physicochemical and optical properties of Ge20Te77-xSe3Ix (x = 0–10) glasses

Thermodynamic modeling of the Ge-Te-I system is carried out. The dependences of the equilibrium concentrations of components in the condensed and vapor phases on temperature and iodine content are established. The compositional effect on the properties of Ge20Te77-xSe3Ix (x = 0–10) and Ge20Te72-ySeyI8 (y = 1, 3, 5) glasses is studied. In the glasses, with an increase in the iodine content, the glass transition temperature decreases, the stability against crystallization increases, and the short-wavelength transparency edge shifts towards shorter wavelengths. Selenium increases the stability of glasses against crystallization and limits transparency in the long-wavelength spectral range. The Ge20Te69Se3I8, Ge20Te67Se5I8, and Ge20Te67Se3I10 compositions are potentially suitable for fabricating optical fibers. The Ge20Te69Se3I8 glass sample with an oxygen impurity content chemically bonded with germanium of less than 50 ppb(wt) and low absorption in the 3–18 μm spectral range is prepared.

Size-induced metal–insulator transition temperature decrease of VO2 nanoparticles obtained by laser irradiation in water

Vanadium dioxide (VO2) is a highly attractive and multifunctional material for technological applications due to its metal–insulator transition, which is accompanied by several orders of magnitude changes in electrical resistivity and optical transmissivity. In this work, we report on the metal–insulator transition of VO2 nanoparticles which are produced by a simple, efficient, and low-cost two-step preparation method based on infrared laser irradiation of V2O5 powder dispersed in water and subsequent stoichiometric stabilization by vacuum annealing at 773 K. VO2 nanoparticles have an average size of 36 nm with facet-like contours and undergo a structural phase transition from a monoclinic to a tetragonal phase, accompanied by a metal–insulator transition occurring around 323 K, which is about 17 K lower than bulk VO2. No evidence of the formation of intermediary metastable phases is observed. Our findings reveal that the size of VO2 nanoparticles is a key parameter to moving the transition closer to room temperature, which is important for many applications.

Stabilising transient ferromagnetic states in nanopatterned FeRh with shape-induced anisotropy

It is well-known that FeRh undergoes an antiferromagnetic to ferromagnetic (FM) phase transition where the high temperature phase is a low coercivity FM material. However, little is known about the effect of lateral confinement on the transition dynamics in FeRh thin films. Here, we pattern FeRh thin films into arrays of nanowires with a large aspect ratio (100:1) and, with ultrafast probing of the magnetic state in an applied magnetic field, we determine the influence of demagnetization fields on the stability of laser induced FM domains. In particular, with pump-probe Kerr measurements, we demonstrate that, when a magnetic field is applied along the nanowire length, the nanowire arrays exhibit an FM phase (>3.0ns) that is longer-lived than that observed for continuous thin films (≈2.0 ns). With electrical measurements, we also show that the transition temperature depends on the relative orientation of the magnetic field. Indeed, when the FeRh film is patterned with sub-μm features, the transition temperature decreases by up to 7 K depending on the field direction at applied magnetic fields of 1 T. The effects of sample heating are explored using finite-element simulations to determine the heat dissipation following laser excitation across a range of FeRh nanowire widths. These simulations confirm that the increased lifetimes of the magnetic-field-aligned FM domains in the nanowire arrays are not due to differences in heat dissipation. This suggests that FM domain growth and relaxation through the ultrafast phase transition in FeRh nanowires is strongly dependent on the shape anisotropy. This knowledge is important for the fine control of the phase transition in patterned FeRh thin films for nanoscale devices.

Dielectric Properties of a Nanocomposite from RbNO3 Incorporated into Pores of Al2O3 Matrix

The present work reports the experimental results of studying linear and nonlinear dielectric properties of a ferroelectric nanocomposite from RbNO3 embedded in pores of an Al2O3 matrix. The dielectric relaxation times were determined above and below the phase transition temperature of pure RbNO3 (436 K). It was shown that for RbNO3 incorporated into nanosized pores of the Al2O3 matrix, a decrease in the phase transition temperature and a change in relaxation times were observed.

Structure and properties of thermoplastic polyimide based on 4′, 4′—(Oxybis (methylene)) bis ([1.1′- bipheny]3-amine) diamine

In this work, a new diamine was designed by connecting flexible structures such as ether bond and aliphatic carbon chain between benzene rings, and was synthesized and purified through simple reactions such as Suzuki reaction. Finally, a series of polyimide (PI) films were synthesized by copolymerization with 4.4`-diaminodiphenyl ether (ODA)\pyromellitic dianhydride (PMDA) in different proportions. We prepared polyimide films with new monomer copolymerization ratios of 1% (PI-1), 5% (PI-2), 10% (PI-3), and 20% (PI-4). The polyimide films showed excellent glass transition temperatures, which were attributed to their unique bent architectures. The mechanical and thermal properties of the thermosets were studied using tensile testing, static thermomechanical analysis (TMA), and thermogravimetric analysis (TGA). As the results, the films exhibited the optimal glass transition temperatures (317.56°C–381.91°C), and the component with the highest copolymerization ratio has a 15% decrease in glass transition temperature compared to the component without copolymerization. Moreover, PI-1-PI-4 showed good heat resistance in the N2 atmosphere. The temperatures corresponding to a 5% heat loss in the films (T5%) were 458.12 °C–548.75°C, respectively.

Study of the Thermal and Mechanical Properties of the Hydrophilic Blend Material Polyhydroxyethyl Methacrylate/Polyethylene Glycol: Hydrogen Bonding Analysis

A hydrophilic blend material is a material that can take up an important quantity of water, which makes it useful in various applications such as tissue engineering, contact lenses, and drug delivery. In this study, the polymeric blend material polyhydroxyethyl methacrylate/polyethylene glycol (pHEMA/PEG) was prepared through a UV photo-polymerization reaction; hexanediol diacrylate (HDDA) and Darocur 1,173 were used, respectively, as a cross-linking agent and a photoinitiator. The main objective of this investigation was to evaluate the impact of the PEG content on the thermal and mechanical properties of the crosslinked pHEMA/HDDA. Many analytical techniques, including Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), and dynamic mechanical analysis (DMA), were used, to analyze the bonding vibrations, the glass transition temperature (Tg), and the elastic and loss moduli, respectively. The complex viscosity was analyzed by a rheometer. The swelling and deswelling behavior of the crosslinked pHEMA/PEG in distilled water were studied over time. It was found that the PEG increased the polymerization rate of the HEMA monomer, and a significant decrease in the glass transition temperature was observed with increasing PEG quantity in the blend material, confirming its plasticizing effect. The mechanical, swelling kinetics, and rheology results showed a threshold effect at 1 wt.% for PEG. The docking analysis showed that there was more hydrogen bonding between the pure pHEMA’s chains, but the integration of PEG decreased the number of hydrogen bonds, which gave flexibility to the blend material, hence; this theoretical conclusion well agreed with the experimental results.

A potential hybrid nanocomposite of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) and fullerene for bone tissue regeneration and sustained drug release against bone infections

Developing a multifunctional biomaterial for bone filling and local antibiotic therapy is a complex challenge for bone tissue engineering. Hybrid nanocomposites of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBHV) with nanohydroxyapatite (nHA), fullerene (C60), and vancomycin (VC) were produced by injection. Fullerene was successfully impregnated with VC, as seen in FTIR. The crystallinity degree of PHBHV was slightly reduced in the presence of C60 and VC (64.3 versus 60.8 %), due to the plasticizing effect of these particles. It also resulted in a decrease in the glass transition temperature (Tg), observed by differential scanning calorimetry (DSC). Dense PHBHV/nHA/C60/VC had a flexural elastic modulus 29 % higher than PHBHV, as a result of the good interface between PHBHV, C60, and nHA – particles of high elastic modulus. Dense disks released 25.03 ± 4.27 % of VC for 14 days, which demonstrated its potential to be an alternative treatment to bone infections. Porous scaffolds of PHBHV/nHA/C60/VC were 3D printed with a porosity of 50 % and porous size of 467 ± 70 μm, and had compression elastic modulus of 0.022 GPa, being a promising material to trabecular bone replacement. The plasticizing effect of C60 improved the printability of the material. The hybrid nanocomposite was non-cytotoxic and showed good ability in adhering macrophage cells.

Hygromechanical Behavior of Polyamide 6.6: Experiments and Modeling.

This paper investigates water absorption in polyamide 6.6 and the resulting hygroscopic swelling and changes in mechanical properties. First, sorption and swelling experiments on specimens from injection molded plates are presented. The observed swelling behavior is dependent on the melt flow direction of the injection molding process. Additionally, thermal analysis and mechanical tensile tests were performed for different conditioning states. The water sorption is accompanied by a decrease in the glass transition temperature and a significant reduction in stiffness and strength. Next, a sequentially coupled modeling approach is presented. A nonlinear diffusion model is followed by mechanical simulations accounting for swelling and concentration-dependent properties. For the mechanical properties, the notion of a "gap" temperature caused by the shift of the glass transition range due to water-induced plasticization is employed. This model enables the computation of local moisture concentration fields and the resultant swelling and changes in stress-strain behavior.

Development and Characterization of New Environmentally Friendly Polylactide Formulations with Terpenoid-Based Plasticizers with Improved Ductility

AbstractThis work addresses the potential of two biobased terpenoids, linalyl acetate and geranyl acetate, as environmentally friendly monomeric plasticizers for polylactide (PLA). Plasticized formulations of PLA containing 10 wt.% and 20 wt.% terpenoids were melt-compounded in a twin-screw co-rotating extruder and, subsequently, processed by injection moulding for further characterization. In addition, a reactive extrusion process (REX) was carried out on plasticized formulations containing 20 wt.% terpenoids with dicumyl peroxide to anchor the plasticizer molecules into the PLA backbone. Both terpenoids led to a remarkable plasticization effect on PLA, with a noticeable increase in ductile properties. In particular, the elongation at break of PLA, around 4.7%, was improved to values above 230% for all the plasticized formulations, even for low terpenoid concentration of 10 wt.%. Terpenoids also provide increased crystallinity because polymers chains have more mobility and are more readily arranged. This was observed by shifting the cold crystallization process to lower temperatures. As with other monomeric plasticizers, a clear decrease in the glass transition temperature from 61.5 °C (neat PLA), to values of around 40 °C for the plasticized formulations with 20 wt.% terpenoid was obtained. The obtained formulations show high potential since the plasticization efficiency of these terpenoids is very high, thus leading to new toughened-PLA formulations with improved ductility.

DODAB vesicles containing lysophosphatidylcholines: The relevance of acyl chain saturation on the membrane structure and thermal properties

The saturated LPC18:0 and unsaturated LPC18:1 lysophosphatidylcholines have important roles in inflammation and immunity and are interesting targets for immunotherapy. The synthetic cationic lipid DODAB has been successfully employed in delivery systems, and would be a suitable carrier for those lysophosphatidylcholines. Here, assemblies of DODAB and LPC18:0 or LPC18:1 were characterized by Differential Scanning Calorimetry (DSC) and Electron Paramagnetic Resonance (EPR) spectroscopy. LPC18:0 increased the DODAB gel-fluid transition enthalpy and rigidified both phases. In contrast, LPC18:1 caused a decrease in the DODAB gel-fluid transition temperature and cooperativity, associated with two populations with distinct rigidities in the gel phase. In the fluid phase, LPC18:1 increased the surface order but, differently from LPC18:0, did not affect viscosity at the membrane core. The impact of the different acyl chains of LPC18:0 and 18:1 on structure and thermotropic behavior should be considered when developing applications using mixed DODAB membranes.

The influence of cassava starch on the properties of PLA/PBS/SCG films for packaging applications

ABSTRACT Fresh fruits and vegetables are perishable products with active metabolism during the post-harvest period; the proper packaging can extend shelf life. The objective of this research has been interested to produce bio-composite film packaging for fresh fruits and vegetables based on poly (lactic acid); PLA, poly butylene succinate; PBS, and natural filler (modified spent coffee grounds; SCG, and cassava starch; ST) by using blow film extruder. The bio-composite film varied in the weight percentage of ST at 0, 5, and 10%wt. control content of PBS at 5%wt. and SCG at 5%wt. The mechanical properties of the PLA blending with PBS can improve % Elongation of the biocomposite film. The cassava starch acts as a nucleating agent present in the cold crystallization temperature was decreased and the degree of crystallinity increased, as well as induced chain mobility, presented in a slight decrease of the glass transition temperature. The SCG and ST particles have a good distribution in the biopolymer phase, the film color was present in light-brown color because of the brown color of SCG particle. The addition of natural filler can improve the UV-light barrier properties, reduce costs, and increase the degradability rate of the film. The WVTR of the biocomposite film was increased with the amount of natural filler added. However, all the biocomposite films presented a water contact angle around 72–75°, this result is essential for the film to apply in a higher humidity environment. The food simulants with aqueous at 40°C and 4°C, 10% ethanol and 3% acetic acid for 10 days were present, the overall migration was less than 10 mg/dm2. The final product from biocomposite film can evaluate the food safety, UV-protection and prolong the shelf-life of fresh vegetables.

High performance biopolymer blend nanocomposites derived from cashew gum/polyvinyl alcohol/boehmite for flexible electronic devices

AbstractThis work reports on a bio‐based polymer blend comprised of polyvinyl alcohol/cashew gum (PVA/CG) embedded with boehmite nanoparticles to tailor the structural, thermal, mechanical properties, and electrical response. The chemical bonding between boehmite and the PVA/CG blend was confirmed by FTIR. The XRD data showed that the nanocomposite films had distinct peaks of boehmite. The SEM images revealed uniformly dispersed morphology at 5 wt% boehmite. The elemental composition of blend nanocomposites was revealed by the EDX analysis. The thermal stability of the blend increases with increasing boehmite, whereas the glass transition temperature decreases. The highest AC conductivity was achieved for PVA/CG/7 wt% boehmite, which was 4.6 times greater than the pure blend. The frequency and temperature‐dependent dielectric constant, modulus and impedance of all films were examined in conjunction with different nanoparticle loadings. Tensile strength and hardness have improved with the addition of boehmite into the PVA/CG blend whereas the elongation at break slightly decreases. The PVA/CG blend had a tensile strength of 31.17 MPa, which increased to 44.66 MPa when 7 wt% boehmite was added. Therefore, eco‐friendly PVA/CG/boehmite films with good thermal stability, mechanical strength, dielectric constant, and conductivity could be a practical green substitute for flexible electronic, charge storage, and electrochemical devices.

Mechanically-reinforced biocompatible hydrogels based on poly(N-isopropylacrylamide) and star-shaped polycaprolactones

The aim of this work was to improve the properties of hydrogels based on poly(N-isopropyl acrylamide) (PNIPAAm) in terms of mechanical features and functionality by combining the polymer with a star-shaped tetrafunctional polycaprolactone (PCL), which was synthesized ad-hoc and introduced into the reaction mixture. The synthesized PCL (coded as PCL-COOH), selected to maintain the biocompatibility of the final material, was designed with a star structure characterized by four strong arms ending with maleic groups to increase the functionalization potential capable of participating in the radical polymerization and adding acid groups to the system. Specifically, various hydrogels were prepared by partially replacing pentaerytritol tetraacrylate (PE-TA), a commercial crosslinker, with increasing concentrations of PCL-COOH in the presence of trihexyl(tetradecyl)phosphonium persulfate (TETDPPS) as non-gas-releasing radical initiator. In addition, frontal polymerization (FP) was employed, a fast and energy efficient technique, potentially capable of promoting the dispersibility of PCL in the polymer matrix.The influence of the star-shaped PCL on the polymerization process as well as on the hydrogel properties in terms of chemical structure, swelling behaviour, thermal and mechanical features was investigated. Indeed, it was found that the presence of PCL allowed the formation of a stable polymerization front up to a concentration of 25 wt%. FT-IR measurements allowed to evaluate the fraction of PCL effectively bonded to the hydrogel structure, while the morphological analysis performed by FE-SEM characterization revealed that the hydrogel pore size tended to decrease as the amount of PCL in the system increased. In addition, the star-shaped PCL was found to affect the material swelling properties, by reducing the swelling ratio without affecting the thermoresponsive behavior. Mechanical tests performed on the neat PNIPAAm hydrogels and on PCL-containing hydrogels, showed a relevant increase in the material stiffness due to the PCL-COOH addition. The DSC characterization results showed a decrease in the glass transition temperature with increasing PCL-COOH content, indicating a partial miscibility of the two polymers likely due to a compatibilization effect of a copolymer formed during the polymerization process. To demonstrate the capability of the hydrogels to retain positively charged molecules, the prepared systems were contacted with solutions containing pararosaniline hydrochloride. The retention capacity as well as the kinetic release were investigated. The measurements evidenced a higher retaining capacity and a lower release rate in the PCL-containing hydrogels. Finally, the biocompatibility and the low citoxicity of the PNIPAAm/PCL hydrogels were confirmed by a cell viability assay using the SH-SY5Y cell line.