Polycaprolactone Content Research Articles

Cryogenic Coaxial Printing for 3D Shell/Core Tissue Engineering Scaffold with Polymeric Shell and Drug-Loaded Core.

For decades, coaxial printing has been widely applied in 3D tissue engineering scaffold fabrication. However, there are few reports regarding polymeric materials application in shell production due to fabrication constraints. In this study, a combination of cryogenic printing and coaxial printing aims to approach the challenge. Polycaprolactone (PCL) and sodium alginate (SA) were selected as the representative shell and core materials to test the feasibility of the coaxial cryogenic printing by optimizing key parameters, including working temperature, air pressure, PCL, and SA concentration. According to the optical and SEM images, the SA core contracts a string inside the PCL shell, illustrating the shell/core structure of the 3D coaxial PCL/SA scaffolds. Besides, the shell/core 3D scaffold possesses a 38.39 MPa Young’s modulus in mechanical tests; the PCL shell could retain at least 8 h in 5 mol/L HCl solution, leading to a fabricated drug-loaded PCL/SA shell/core “responsive” to acidic pH. In summary, coaxial cryogenic printing was developed to fabricate 3D scaffolds with a PCL/SA shell/core scaffold, broadening the material range of coaxial printing and providing promising applications in drug release.

Continuous Nanoprecipitation of Polycaprolactone in Additively Manufactured Micromixers.

The polymeric ouzo effect is an energy-efficient and robust method to create nanoparticles with biologically degradable polymers. Usually, a discontinuous or semi-continuous process is employed due to its low technical effort and the fact that the amount of dispersions needed in a laboratory is relatively small. However, the number of particles produced in this method is not enough to make this process economically feasible. Therefore, it is necessary to improve the productivity of the process and create a controllable and robust continuous process with the potential to control parameters, such as the particle size or surface properties. In this study, nanoparticles were formulated from polycaprolactone (PCL) in a continuous process using additively manufactured micromixers. The main goal was to be able to exert control on the particle parameters in terms of size and zeta potential. The results showed that particle size could be adjusted in the range of 130 to 465 nm by using different flow rates of the organic and aqueous phase and varying concentrations of PCL dissolved in the organic phase. Particle surface charge was successfully shifted from a slightly negative potential of −14.1 mV to a negative, positive, or neutral value applying the appropriate surfactant. In summary, a continuous process of nanoprecipitation not only improves the cost of the method, but furthermore increases the control over the particle’s parameters.

Influence of morphology on the dynamic and quasi‐static energy absorption of polylactic acid‐based lattice structures

AbstractThe aim of this work was to investigate the difference between energy absorption (EA) of a lattice structure under quasi‐static and dynamic loading, as influenced by morphology. Lattices were manufactured from blends of polylactic acid (PLA) and polycaprolactone (PCL), with and without a compatibilizer. Under quasi‐static compression, PLA and blends with low PCL content provided the greatest EA. Above 30% PCL, a drastic decrease in EA was observed as the ductility increased. The morphology of the blends under slower loading played little role in affecting EA, as the lattice's performance was mainly dictated by the ductility of the blend. However, under dynamic loading brittle lattices provided poor EA, however, at 30% PCL, EA was significantly higher, improved further with including a compatibilizer. At 10% PCL an erratic dispersion of PCL in the PLA matrix was observed, whilst at 50% the morphology was co‐continuous. A uniformly, finely dispersed droplet morphology was observed at 30% PCL. The ductility and morphology of the matrix paired with the complex loading scenario led to optimal EA under dynamic loading. The partial bonding between PCL and PLA provided clear improvement to EA, however, this effect was vastly different under quasi‐static loading.

Characteristics of ultrafine particles emitted from 3D-pens and effect of partition on children's exposure during 3D-pen operation.

A three-dimensional (3D) printing pen is a popular writing instrument that uses a heated nozzle, and is similar to a 3D-printer. Processing thermoplastic filaments with a 3D-pen can emit ultrafine particles (UFPs). 3D-pen education sessions were held with "∏"-shaped partitions for the prevention of coronavirus disease (COVID-19). This study aimed to characterize UFP emissions from two types of 3D-pens and evaluate the influence of "∏"-shaped partitions on UFP exposure. Measurements of UFP emission rates and the size distribution of particles emitted from 3D-pens were conducted in a chamber (2.5m3 ). The partition's influence on UFP exposure was evaluated with and without a "∏"-shaped partition on a desk. A scanning mobility particle sizer (SMPS) and an optical particle spectrometer (OPS) were used to measure the particle number concentration (PNC) and size distribution. For both 3D-pen A and B, the average emission rates were statistically significantly highest for acrylonitrile butadiene styrene (ABS) filament (8.4×106 [3.4] particles/min and 1.1×106 [1.8] particles/min), followed by polylactic acid (PLA) (2.8×105 [1.5] particles/min and 4.8×104 [1.8] particles/min) and polycaprolactone (PCL) filaments (1.4×104 [2.8] particles/min and 2.0×104 [2.8] particles/min). For all filaments, particles in the Aitken mode (30-100nm) accounted for the highest proportion. In 3D-pen A, PNCs were higher with the partition than without it for ABS (1.2×106 [1.15] particles/cm3 vs. 1.4×105 [1.29] particles/cm3 ) and PLA (6.2×105 [1.38] particles/cm3 vs. 8.9×104 [1.12] particles/cm3 ), whereas for 3D-pen B, they were higher with the partition for ABS (9.6×105 [1.13] particles/cm3 vs. 4.9×105 [1.22] particles/cm3 ) only. With the partition installed, PNCs decreased to the background level after the operation ended, whereas it took 2-6min without the partition. However, the mass concentrations of PLA and PCL with 3D-pen A were not statistically significantly different with respect to the partition status. The use of 3D-pens with a partition can lead to high UFP exposure. Therefore, guidelines are required for the safe use of 3D-pens and partitions.

Polycaprolactone and polycaprolactone triol blends to obtain a stable liquid nanotechnological formulation: synthesis, characterization and in vitro – in vivo taste masking evaluation

The use of polymeric blends is a potential strategy to obtain novel nanotechnological formulations aiming at drug delivery systems. Saquinavir, an antiretroviral drug, was chosen as a model drug for the development of new stable liquid formulations with unpleasant taste masking properties. Three formulations containing different polymeric ratios (1:3, 1:1 and 3:1) were prepared and properly characterized by particle size distribution, zeta potential, pH, drug content and encapsulation efficiency measurements. The stability was verified by monitoring the zeta potential, particle size distribution, polydispersity index and drug content by 90 days. The light backscattering analysis was used to early identify possible phenomena of instability in the formulations. The in vitro drug release and saquinavir cytotoxicity were evaluated. The in vitro and in vivo taste masking properties were studied using an electronic tongue and a human sensory panel. All formulations presented nanometric sizes around 200 nm and encapsulation efficiency above 99%. The parameters evaluated for stability remained constant throughout 90 days. The in vitro tests showed a controlled drug release and absence of toxic effects on human T lymphocytes. The electronic tongue experiment showed taste differences for all formulations in comparison to drug solutions, with a more pronounced difference for the formulation with higher polycaprolactone content (3:1). This formulation was chosen for in vivo sensory panel evaluation which results corroborated the electronic tongue experiments. In conclusion, the polymer blend nanoformulation developed herein showed the promising application to incorporate drugs aiming at pharmaceutical taste-masking properties.

Carbon Nanotube Reinforced Poly(ε-caprolactone)/Epoxy Blends for Superior Mechanical and Self-Sensing Performance in Multiscale Glass Fiber Composites.

In this paper, a novel carbon nanotube (CNT) polycaprolactone (PCL), epoxy, and glass fiber (GF) composite is reported. Here, the nanoreinforced composites show a flexural strength increase of around 30%, whereas the interlaminar shear strength increases by 10–15% in comparison to unenhanced samples. This occurs because the addition of the CNTs induces a better PCL/epoxy/GF interaction. Furthermore, the nanoparticles also give novel functionalities to the multiscale composite, such as strain and damage monitoring. Here, the electrical response of the tensile- and compressive-subjected faces was simultaneously measured during flexural tests as well as the transverse conductivity in interlaminar tests, showing an exceptional capability for damage detection. Moreover, it was observed that the electrical sensitivity increases with PCL content due to a higher efficiency of the dispersion process that promotes the creation of a more uniform electrical network.

Miscibility and enzymatic degradability of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate)-based polyester blends by PHB depolymerase and lipase

Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH) containing 5 and 17 mol% 3-hydroxyhexanoate has been blended with atactic poly(3-hydroxybutyrate) (PHB), polycaprolactone (PCL), and polybutylene succinate (PBS) at different ratios by the solvent-casting method. PHBH-5%/atactic PHB and PHBH-17%/atactic PHB showed a single glass-transition temperature (Tg), indicating miscibility in the amorphous state. Immiscibility was observed in the PHBH-5%/PCL and PHBH-17%/PCL blends based on the non-transitioning Tg of the PHBH component, presence of two distinct Tg values for some of the blend films, and individual crystallization manner. The thermal properties and spherulitic morphologies of the PHBH-5%/PBS blend films suggested partial miscibility. The enzymatic degradability of the three types of blends by Ralstonia pickettii T1 PHB depolymerase and Burkholderia cepacia lipase was investigated. Depending on the enzyme–substrate specificity, miscibility, and phase structure of the blend, the variation of the enzymatic degradation rate with the blend ratio was different among the three types of blends. The weight loss rate of PHBH-5%/atactic PHB was higher than that of PHBH-17%/atactic PHB when degraded by PHB depolymerase. The PCL component accelerated the weight loss rate of PHBH-17%/PCL but decreased that of PHBH-5%/PCL. Lipase barely eroded PHBH-5%/PBS, but the weight loss rate increased as the PCL content increased. From quantitative analysis of the water-soluble products liberated during degradation, the degradation manners of the blends by PHB depolymerase and lipase are discussed.

Influence of elastin on the properties of hybrid PCL/elastin scaffolds for tissue engineering

AbstractDeveloping scaffolds by combining different polymers in order to improve the properties of the bare polymers has become an extensively applied practice. Polycaprolactone (PCL) is a synthetic polyester with outstanding properties for tissue engineering (TE), although it does have certain drawbacks that can be counteracted by combining it with other biopolymers. The biopolymer elastin is an essential functional component of the dermal extracellular matrix. Therefore, the aim of this work was to produce binary systems comprising a combination of PCL (16 wt/vol%) and different concentrations of elastin (2 and 4 wt/vol%) to evaluate how the protein affects the matrix. To this end, the morphological, physicochemical, mechanical and biological properties of the aforementioned scaffolds were further characterized, observing that PCL/elastin is a suitable mixture as it improves the wettability of PCL when combined with elastin (the contact angles were reduced from 102 to ca. 70°). In addition, mixing PCL with a small quantity of elastin (2%) improved the mechanical properties of PCL‐based scaffolds (Young's modulus increased from 36 to 69 MPa and the maximum stress increased from 11 to 34 MPa).

Step-by-step design of poly (ε-caprolactone) /chitosan/Melilotus officinalis extract electrospun nanofibers for wound dressing applications

Composition of polymers and choosing the type of solvents in electrospinning systems is of great importance to achieve a mat with optimal properties. In this work, with emphasizing the influence of a novel solvent system, an electrospun wound dressing was designed in four steps. Firstly, to study the effect of polymer-solvent interactions and electrospinning distance, a constant amount of polycaprolactone (PCL) was dissolved at different compositions of formic acid (FA)/dichloromethane (DCM) and was electrospun at different distances. The composition of 80FA/20DCM and distance of 15 cm were selected as optimal conditions by lowest average diameter of fibers and simultaneously good surface uniformity. In the second step, the concentration of PCL was considered variable to achieve the lowest diameter of fibers. Finally, in the third and fourth steps, different concentrations of chitosan (CN) and constant dosage of Melilotus officinalis (MO) extract were added to the solution. The extract contained fibers had a mean diameter of 275 ± 41 nm which is in the required condition for wound caring. Eventually, the optimized PCL/CN and PCL/CN/MO specimens were evaluated by FTIR, DSC, Tensile, water contact angle, antibacterial assays, cell viability, and drug release analysis for determining their function and properties.

Thermal Analysis of Organic and Nanoencapsulated Electrospun Phase Change Materials

Latent heat stored in phase change materials (PCM) can greatly improve energy efficiency in indoor heating/cooling applications. This study presents the materials and methods for the formation and characterization of a PCM layer for a latent heat thermal energy storage (LHTES) application. Four commercially available PCMs comprising the classes of organic paraffins and organic non-paraffins were selected for thermal storage application. Pure organic PCM and PCM in water emulsions were experimentally investigated. PCM electrospun microfibers were produced by a co-axial electrospinning technique, where solutions of Polycaprolactone (PCL) 9% w/v and 12% w/v in dichloromethane (DCM) were used as the fiber shell materials. PCM emulsified with sodium dodecyl sulfate (SDS), and Polyvinylalcohol 10% w/v (PVA) constituted the core of the fibers. The thermal behavior of the PCM, PCM emulsions, and PCM electrospun fibers were analyzed with differential scanning calorimetry (DSC). A commercial organic paraffin with a phase change temperature of 18 °C (RT 18) in its pure and emulsified forms was found to be a suitable PCM candidate for LHTES. The PVA-PCM electrospun fiber matrix of the organic paraffin RT18 with a PCL concentration of 12% w/v showed the most promising results leading to an encapsulation efficiency of 67%.

In-vivo assessment of a tissue engineered vascular graft computationally optimized for target vessel compliance

Tissue engineered vascular grafts (TEVGs) have the ability to be tuned to match a target vessel’s compliance, diameter, wall thickness, and thereby prevent compliance mismatch. In this work, TEVG compliance was manipulated by computationally tuning its layered composition or by manipulating a crosslinking agent (genipin). In particular, these three acelluluar TEVGs were compared: a compliance matched graft (CMgel - high gelatin content); a hypocompliant PCL graft (HYPOpcl - high polycaprolactone content); and a hypocompliant genipin graft (HYPOgen - equivalent composition as CMgel but hypocompliant via increased genipin crosslinking). All constructs were implanted interpositionally into the abdominal aorta of 21 Sprague Dawley rats (n=7, males=11, females=10) for 28 days, imaged in-vivo using ultrasound, explanted, and assessed for remodeling using immunofluorescence and two photon excitation fluorescence imaging. Compliance matched grafts remained compliance-matched in-vivo compared to the hypocompliant grafts through 4 weeks (p<0.05). Construct degradation and cellular infiltration was increased in the CMgel and HYPOgen TEVGs. Contractile smooth muscle cell markers in the proximal anastomosis of the graft were increased in the CMgel group compared to the HYPOpcl (p=0.007) and HYPOgen grafts (p=0.04). Both hypocompliant grafts also had an increased pro-inflammatory response (increased ratio of CD163 to CD86 in the mid-axial location) compared to the CMgel group. Our results suggest that compliance matching using a computational optimization approach leads to the improved acute (28 day) remodeling of TEVGs. To the authors’ knowledge, this is the first in-vivo rat study investigating TEVGs that have been computationally optimized for target vessel compliance.

Preparation, characterization, and in vitro/vivo evaluation of dexamethasone/poly(ε-caprolactone)-based electrode coatings for cochlear implants

With dexamethasone as the model drug and polycaprolactone (PCL) as the carrier material, a drug delivery coating for cochlear electrodes was prepared, to control cochlear fibrosis caused by cochlear implantation. A dexamethasone/poly (ε-caprolactone)-based electrode coating was prepared using the impregnation coating method. Preparation parameters were optimized, yielding 1 impregnation instance, impregnation time of 10 s, and PCL concentration of 10%. The coating was characterized in vitro using scanning electron microscopy, a universal machine, high-performance liquid chromatography, and CCK-8. The surface was porous and uniformly thick (average thickness, 48.67 µm)—with good flexibility, long-term slow drug release, and optimal drug concentration—and was biologically safe. The experimental results show that PCL is an ideal controlled-release material for dexamethasone as a drug carrier coating for cochlear implants.

Vascular Grafts with Tailored Stiffness and a Ligand Environment via Multiarmed Polymer Sheath for Expeditious Regeneration.

The bypass graft is the mainstream of surgical intervention to treat vascular diseases. Ideal bypass materials, yet to be developed, require mechanical properties, availability, clinically feasible manufacturing logistics, and bioactivities with precise physicochemical cues defined to guide cell activities for arterial regeneration. Such needs instigated our fabrication of vascular grafts, which consist of coaxial, nanostructured fibers exhibiting a polycaprolactone (PCL) core and a photoclickable, 4-arm thiolated polyethylene glycol-norbornene (PEG-NB) sheath. The graft strength and bioactivity were modulated by the PCL concentration and the peptides (RGD, transforming growth factor β-1 or TGF-β1) conjugated to thiol-ene of PEG-NB, respectively. Structural, physical, and mechanical characterizations demonstrated that the fibrous grafts mimicked the key features of the native extracellular matrix, including a crosslinked fiber network for structural stability, viscoelasticity emulating arteries, hydration property, and high porosity for cell infiltration. Meanwhile, these grafts displayed strength and toughness exceeding or meeting surgical criteria. Furthermore, the grafts with higher PCL concentration (3 vs 1.8%) showed thicker fibers, lower porosity and pore size, and increased elastic and storage moduli. Graft bioactivity was determined by the mesenchymal stem cell (MSC) behaviors on the grafts and arterial regeneration in vivo using interposition grafting. Results showed that the cell adhesion and proliferation increased with the RGD density (25 vs 5 mM). After 1 week implantation, all peptide-functionalized PCL/PEG-NB grafts with or without MSC preseeding, as opposed to PCL grafts, showed expeditious endothelial lining, abundant vascular cell infiltration, and matrix production. Compared to RGD grafts, RGD/TGF-β1 grafts enhanced MSC differentiation into smooth muscle cells in vitro and developed thicker smooth muscle cell layers in vivo. Overall, the versatile porous vascular grafts offer superior properties and tunability for future translation.

Effect of the Incorporation of Polycaprolactone (PCL) on the Retrogradation of Binary Blends with Cassava Thermoplastic Starch (TPS).

The effects of incorporating polycaprolactone (PCL) in three binary blends with cassava thermoplastic starch (TPS) at TPS/PCL ratios of 60/40, 50/50, and 40/60 were studied. TPS previously obtained by single-screw extrusion was manually mixed with PCL and then transformed by extrusion. The results’ analysis focused mainly on monitoring the retrogradation phenomenon in TPS for different storage times at two relative humidities (29% and 54%) and constant temperature (25 °C). With the plasticization of the starch, a predominantly amorphous mass was generated, as evidenced by the scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier transform infrared (FTIR) results. The results suggested that two opposite processes coexisted simultaneously: retrogradation, which stiffened the material, and plasticization, which softened it, with the latter mechanism predominating at short times and reversing at longer times. With the incorporation of PCL, immiscible blends were obtained in which TPS was the dispersed phase; the mechanical properties improved with the amount of PCL added. The properties of the binary blends as a function of time showed a trend similar to that observed for TPS alone; this finding indicated that the TPS/PCL interactions were not strong enough to affect the structural changes in the TPS, which continued to occur regardless of the PCL content. Finally, it was found that for the binary blend, the relative humidity during storage was more significant to the retrogradation phenomenon than the amount of PCL.

Thermal and mechanical properties of UHMWPE/HDPE/PCL and bioglass filler: Effect of polycaprolactone

AbstractPolymeric composites based on polyethylene, high‐density polyethylene (HDPE) and ultra‐high‐molecular‐weight polyethylene (UHMWPE) with polycaprolactone (PCL) and a ceramic filler (bioglass type) were studied in terms of their thermal and mechanical behavior. Two polyethylene ratios (10/90 and 30/70% wt/wt of UHMWPE/HDPE) and two PCL content ratios (5% and 10% wt/wt) were used. The obtained composites were characterized by differential scanning calorimetry, melt flow index, Fourier transform infrared spectroscopy, scanning electron microscopy, and X‐ray diffraction. The results indicate a nonchemical interaction between polyethylene, especially the UHMWPE, and PCL and that the composites' thermal transitions vary from the parent polymers and depend on the PCL concentration. The PCL's melting temperature in the composite was reduced, showing a new one. Also, the melting enthalpy of polyethylene was reduced when the concentration of PCL increased. The mechanical behavior depends on both the polyethylene ratio and the PCL content. The composite with 30% wt/wt of UHMWPE and 10% wt/wt of PCL showed the highest toughness value due to the good interaction between polymers. These new composites may be attractive for biomedical applications and could be evaluated, for example, as materials for prostheses.

TUNING SURFACE ROUGHNESS OF ELECTROSPUN POLY CAPROLACTONE FIBRES BY SINGLE SOLVENT ELECTROSPINNING SYSTEM

Secondary surface texture or surface roughness is having a powerful impact on morphological variety and magnifies the application areas of electrospun fibres. This paper for the first time assesses the formation of varying degrees of surface pores on electrospun poly caprolactone (PCL) fibres by using a single solvent system. PCL solutions were prepared by dissolving PCL granules in dichloromethane (DCM) at the concentration of 5, 10, 15 and 20% (w/v), before being subjected to the electrospinning process at lower kV values of 5, 10 and 15, respectively. The morphology of electrospun fibres was characterised by field emission scanning electron microscope (FESEM). The resultant PCL fibres showed a highly porous surface was formed at lower PCL concentration. The surface roughness of PCL fibres was increased gradually with the increment of PCL concentration. The formation of porous surface was mainly due to the fast phase separation process while pore size and pore size distribution was found to depend on the blend composition.

Physicochemical and In Vitro Degradation Behaviors of Fibrous Membranes with Different Polycaprolactone and Gelatin Proportions.

Mechanical and degradation properties are crucial factors of guided tissue/bone regeneration (GTR/GBR) membranes. In this work, a series of fibrous membranes with different ratios of polycaprolactone (PCL) and gelatin (Gel) were prepared (PCL:Gel = 1:9 (P1G9), 3:7 (P3G7), 5:5 (P5G5), 7:3 (P7G3), and 9:1 (P9G1)) by electrospinning, and their physicochemical properties and In Vitro degradation behaviors were systematically investigated. Mechanical tests showed that tensile strength was enhanced with the presence of Gel, and the tensile strength of the P9G1 membrane reached nearly three times that of the pure PCL membrane. The degradation rate of the composite membranes could be adjusted by controlling the ratio of PCL and Gel; the higher the Gel content was, the faster the degradation of the PCL/Gel membrane. The higher PCL content favored maintaining the fibrous structure of the electrospun membranes. These findings will be beneficial for designing PCL/Gel composite materials for biomedical applications.

Composition-property relationship of polyurethane networks based on polycaprolactone diol

This work was focused on the synthesis of polyurethane networks (PUNs) based on polycaprolactone (PCL) as soft segment (SS) and Boltorn® aliphatic hyperbranched polyester of the second pseudo generation and 4,4′-diphenylmethane diisocyanate (MDI) as the parts of the hard segments (HS), by a two-step solution polymerization. In order to find the best ratio between HS and SS to achieve good thermal and mechanical properties, suitable hydrophobicity and morphology of the PUNs, various experimental analyses were conducted. The obtained results revealed that features of the PUNs highly depend on the PCL content. The increase in the PCL content leads to the increase in thermal stability, hydrophobicity and appearance of the microphase separation, but on the other side, it also leads to the decrease in storage modulus in the rubbery plateau, crosslinking density and glass transition temperatures of PUNs. This work shows that features of PUNs can be easily adjusted for a specific application by careful selection of the SS and HS ratio.

Proper Blends of Biodegradable Polycaprolactone and Natural Rubber for 3D Printing.

Flexible thermoplastic elastomers (TPE) were prepared for fused deposition modeling (FDM) or 3D printing. These materials can be used for medical purposes such as disposable soft splints and other flexible devices. Blends of 50% epoxidized natural rubber (ENR-50) and block rubber (Standard Thai Rubber 5L (STR5L)) with polycaprolactone (PCL) were produced and compared. The purpose of this study was to investigate the properties of natural rubber (NR) and PCL in simple blends with PCL contents of 40%, 50%, and 60% by weight (except at 75% for morphology study) in the base mixture (NR/PCL). The significant flow factors for FDM materials, such as melting temperature (Tm) and melt flow rate (MFR), were observed by differential scanning calorimetry (DSC) and via the melt flow index (MFI). In addition, the following mechanical properties were also determined: tensile strength, compression set, and hardness. The results from DSC showed that the melting temperature changed slightly (1–2 °C) with amount of PCL used, and there was a suspicious point in the 50/50 blends with both types of rubber. The lowest melting enthalpy of both blends was found at the 50/50 blended composition. The MFI results showed that PCL significantly affected the melt flow rate of both blends. The ENR-50/PCL blend flowed better than the STR5L/PCL blend. The conclusion was that this was due to the morphology of its phase structure having better uniformity than that of the STR5L/PCL blend. In compression set testing or measuring shape recovery, rubber directly influenced the recovery in all blends. The ENR-50/PCL blend had less recovery than the STR5L/PCL blend, probably due to the functional effects of epoxide groups and polarity mismatch. The hard phase PCL significantly affected the hardness of samples but improved shape recovery of the material. The ENR-50/PCL blend had better tensile properties than the STR5L/PCL blend. The elongation at break of both blends improved with a high rubber content. Hence, the ENR-50/PCL blend was superior to STR5L/PCL for printing purposes due to its better miscibility, uniformity, and flow, which are the keys to success for optimizing the fused deposition modeling conditions as well as the overall mechanical properties of products. Most blends in this study were only slightly different, but the 50/50 blend of ENR-50/PCL seemed to be near optimal for 3D printing.

Effect of cosolvent on properties of non-woven porous neomycin-loaded poly(lactic acid)/polycaprolactone fibers

In this research, the model drug neomycin was loaded into biodegradable fibers containing poly(lactic acid) (PLA) blended with polycaprolactone (PCL) as a matrix using the rotational jet spinning technique. The mixed polymer solution of PLA and PCL in dichloromethane and a cosolvent of dichloromethane and ethanol was prepared. The effect of the spinning condition such as a rotational speed (1000–5000 rpm), a ratio between PLA and PCL (80:20, 75:25 and 70:30) and a ratio between dichloromethane and ethanol (90:10 and 80:20) as a cosolvent on porosity percentage and morphology were investigated. The results demonstrated that when the PLA concentration increased, the fibers diameter increased but the porosity percentage decreased due to the low mobility of PLA. Upon increasing the rotational speed, the fibers diameter decreased because of highly developed jet, which overcomes the intermolecular forces between polymer chains and polymer-solvent interaction. When incorporating the higher concentration of PCL into PLA matrix, the specific area tended to decrease. The results also showed the different rough surface fibers prepared from cosolvent and dichloromethane, resulting from the different evaporation rate of the solvents compared with the fibers spun using only dichloromethane as a solvent. The porous structure of the fibers changed when using a cosolvent due to the phase inversion before the solvent evaporated and the different evaporation rates between dichloromethane and ethanol. The specific area increased upon adding ethanol into the polymer solution. In vitro drug release studies concluded that the higher specific area increases the efficiency of drug release and drug loading of fibers.