Miscible Polymer Research Articles

Screening of Polymers for Oral Ritonavir Amorphous Solid Dispersions by Film Casting

Background/Objectives: Drug–polymer interactions and miscibility promote the formation and performance of amorphous solid dispersions (ASDs) of poorly soluble drugs for improved oral bioavailability. The objective of this study was to employ drug–polymer interaction calculations and small-scale experimental characterization to screen polymers for potential ASDs of ritonavir. Methods: Seven polymers across four polymer types were screened as follows: an enteric one (EudragitS100), amphiphilic ones (HPMCAS-L, HPMCAS-H, and their 1:1 combination), hydrophilic ones (PEG-6000, PVP-VA), and a surfactant (Soluplus), including PVP-VA as a positive control, as the commercial ASD employs PVP-VA. Drug–polymer interaction calculations were performed for Hansen solubility parameter, Flory–Huggins parameter, and glass transition temperature. ASDs were prepared via film casting. Experimental characterizations included drug solubility in polymer solutions, polymer inhibition of drug precipitation, polarized light microscopy, differential scanning calorimetry, solubilization capacity, and dissolution studies. Results: HPMCAS-L, HPMCAS L:H, and Soluplus, along with the positive control PVP-VA, were identified as polymers for potential ASDs of ritonavir, with HPMCAS-L and PVP-VA being preferable. HPMCAS-L and the positive control PVP-VA were always viable for both 20% and 40% drug loads across all tests. Films with each of these four polymers showed improved dissolution compared to amorphous ritonavir without polymer. Drug–polymer interaction calculations anticipated the unfavorable small-scale experimental results for PEG-6000 and EudragitS100. Conclusion: Overall, the results contribute towards a resource-sparing approach to identify polymers for ASDs.

A Miscibility Study of p(MMA-co-HEMA)-Based Polymer Blends by Thermal Analysis and Solid-State NMR Relaxometry.

Ternary amorphous solid dispersions (ASDs) consist of a multicomponent carrier with the aim of improving physical stability or dissolution performance. A polymer blend as a carrier that combines a water-insoluble and a water-soluble polymer may delay the drug release rate, minimizing the risk of precipitation from the supersaturated state. Different microstructures of the ternary ASD may result in different drug release performances; hence, understanding the phase morphology of the polymer blend is crucial prior to drug incorporation. The objective of this study is to investigate the miscibility of the water-insoluble p(MMA-co-HEMA) and water-soluble polymers such as HPC, HPMC, HPMC-AS, and Soluplus. To prepare the polymer blends, p(MMA-co-HEMA) was spray dried in 80/20 and 90/10 (w/w) ratios with one of the water-soluble polymers. Thermal analysis (mDSC and DMA) and solid-state (ss)NMR relaxometry were applied to study the miscibility of these blends. No conclusions regarding miscibility could be drawn from the Tg measurements by thermal analysis. However, phase-separation could be demonstrated in all blends by ssNMR relaxometry. Moreover, by measuring both the T1ρH and T1H relaxation times, domain sizes between 5 and 50 nm could be estimated. This work shows the importance of using complementary analytical techniques to investigate polymer miscibility.

Application of the Thermal Analysis of Frozen Aqueous Solutions to Assess the Miscibility of Hyaluronic Acid and Polymers Used for Dissolving Microneedles.

Background: The combination of multiple polymers is anticipated to serve as a means to diversify the physical properties and functionalities of dissolving microneedles. The mixing state of components is considered as a crucial factor in determining their suitability. Objectives: The purpose of this study was to elucidate whether thermal analysis of frozen aqueous solutions can appropriately predict the miscibility of hyaluronic acid (HA) and other polymers used for dissolving microneedles prepared by a micromolding method. Methods: Aliquots of aqueous polymer solutions were applied for thermal analysis by heating the samples from -70 °C at 5 °C/min to obtain the transition temperature of amorphous polymers and/or the crystallization/melting peaks of polymers (e.g., polyethylene glycol (PEG)). Films and dissolving microneedles were prepared by air-drying of the aqueous polymer solutions to assess the polymer miscibility in the solids. Results: The frozen aqueous single-solute HA solutions exhibited a clear Tg' (the glass transition temperature of maximally freeze-concentrated solutes) at approximately -20 °C. The combination of HA with several polymers (e.g., dextran FP40, DEAE-dextran, dextran sulfate, and gelatin) showed a single Tg' transition at temperatures that shifted according to their mass ratio, which strongly suggested the mixing of the freeze-concentrated solutes. By contrast, the observation of two Tg' transitions in a scan strongly suggested the separation of HA and polyvinylpyrrolidone (PVP) or HA and polyacrylic acid (PAA) into different freeze-concentrated phases, each of which was rich in an amorphous polymer. The combination of HA and PEG exhibited the individual physical changes of the polymers. The polymer combinations that showed phase separation in the frozen solution formed opaque films and microneedles upon their preparation by air-drying. Coacervation occurring in certain polymer combinations was also suggested as a factor contributing to the formation of cloudy films. Conclusions: Freezing aqueous polymer solutions creates a highly concentrated polymer environment that mimics the matrix of dissolving microneedles prepared through air drying. This study demonstrated that thermal analysis of the frozen solution offers insights into the mixing state of condensed polymers, which can be useful for predicting the physical properties of microneedles.

Highly miscible bio-based poly(lactic acid)/acetylated cellulose ether ultrafiltration membranes with improved water permeances

Biopolymer-based membranes are eco-friendly alternatives to petroleum-based membranes. However, biopolymers often require harsh membrane fabrication conditions due to their low solubilities, which are incompatible with general non-solvent-induced phase separation (NIPS). Thus, establishing mild blending conditions for NIPS membrane production is needed. This study developed ultrafiltration membranes by blending poly (lactic acid) (PLA) and acetylated cellulose ether (ACE), both of which are derived from renewable resources, using NIPS under mild conditions. We investigated the effects of PLA proportion on the structural, chemical, and thermal properties of the blend membranes and assessed polymer miscibility using theoretical models. Results indicated excellent miscibility with a single glass transition temperature. The 1:1 PL A/ACE membrane demonstrated the lowest water contact angle of 45°, 35 % lower than that of the pure PLA membrane. Additionally, its pure water permeance was 179.4 LMH/bar, significantly higher than 103.4 LMH/bar of the pure PLA membrane. Flux recovery ratio at pH = 4 was 69.5 for the blend membrane as compared to 70.6 for the PLA membrane. At pH = 7, all membranes could be fully recovered via physical washing, even those fouled with bovine serum albumin. This study successfully fabricates PLA/ACE-based membranes with outstanding properties under mild conditions.

Estimation of the Shear Viscosity of Mixed-Polymer Materials for Screw Extrusion-Based Recycling Process Modeling.

The scope of this work is the development of a method to estimate the temperature and shear rate-dependent viscosity of mixtures composed of two polymers. The viscosity curve of polymer mixtures is crucial for the modeling and optimization of extrusion-based recycling, which is the most efficient way to recycle polymeric materials. The modeling and simulation of screw extruders requires detailed knowledge of the properties of the processed material, such as the thermodynamic properties, the density, and the rheological behavior. These properties are widely known for pure materials; however, the incorporation of impurities, like other polymers in recycled materials, alters the properties. In this work, miscible, immiscible, and compatibilized immiscible polymer mixtures are considered. A new method based on shear stress is proposed and compared to the shear rate-based method. Several mixing rules are evaluated for their accuracy in predicting mixture viscosity. The developed methods allow the prediction of the viscosity of a compatibilized immiscible mixture with deviations below 5% and that of miscible polymer mixtures with deviations below 3.5%.

Additive manufacturing and microstructure effects on thermal and mechanical properties of ply-hybrid carbon and glass fiber composites

The fiber hybridization in high-strength composites is one of the most researched strategies to enhance their limited toughness. In this work, hybrid composites at laminate level by stacking together plies of carbon and glass fiber were prepared using fused filament fabrication (FFF) technique. The large void content and the poor adhesion between layers attributed to this technology are overcome by the addition of an optimized thermo-pressurized treatment. The analysis of post-processing temperature effects on the microstructural, thermal and interlaminar properties of additive manufactured hybrid composites, revealed a progressive porosity reduction preserving the dimensional accuracy. The enhancement of mechanical properties is due to different contributions that occurred during post-processing: (i) drying effect, which reduces the plasticization of the composites; (ii) improvement of interface adhesion due to the miscibility of polymers; and (iii) significant porosity reduction (below 1 %). This work opens a wider space of possibilities, since FFF allows more complex designs than traditional composite manufacturing, and additionally provides an approach to promote molecular diffusion at the interface, which is the most critical region of FFF parts.

Assessment of World’s First Two Polymer Injectivity Tests Performed in Two Giant High-Temperature/High-Salinity Carbonate Reservoirs Using Single-Well Simulation Models and Pressure Falloff Tests Analysis

Summary Polymer flooding is a mature enhanced oil recovery (EOR) technology that has been widely implemented around the world for more than 60 years. Polymer flooding mostly targets medium- to high-permeability sandstone reservoirs with moderate salinity, hardness, and temperatures. However, in the last few years, the envelope of polymer flooding has been expanded to harsher reservoir conditions of high-temperature and high-salinity mixed-wet to oil-wet heterogeneous carbonate reservoirs. Development of novel polymers and innovative field application concepts has allowed for the reconsideration of polymer-based EOR as a promising technology to improve sweep efficiency for these challenging reservoirs. Polymer injectivity is one of the key challenges for polymer flooding projects and requires a rigorous derisking program that includes laboratory and field testing. A comprehensive laboratory program was designed to assess and investigate polymer thermal stability, polymer rheology in porous media, adsorption, and injectivity using reservoir core samples. In addition, two polymer injectivity tests (PITs) were performed in two giant light oil (0.3 cp) carbonate reservoirs in onshore Abu Dhabi under harsh conditions of high salinity (>200 g/L), high divalent ions (>20 g/L), high temperature (>250°F), and H2S concentration of up to 40 ppm. The polymer used during the two PITs (PIT 1 2019 and PIT 2 2021) is a new generation of EOR polymer (SAV 10) with high 2-acrylamido-tertiary-butyl sulfonic acid content that was specifically developed to tolerate such harsh conditions. This paper is focused on the interpretation of the PITs and lessons learned for future polymer-based EOR projects. The detailed data acquired in both tests were used to evaluate the polymer injectivity at representative field conditions and in-depth mobility reduction. The PITs together with the extensive laboratory studies are part of a thorough derisking program for the upcoming world’s first innovative hybrid EOR multiwell pilots—simultaneous injection of miscible gas and polymer (SIMGAP) and simultaneous injection of water and polymer (SIWAP). Both PITs are composed of three stages that include a multirate waterflood baseline, polymer injection using different rates, and polymer concentrations followed by extended chase waterflooding. In addition, a sequence of multiple pressure falloff (PFO) tests was acquired during the PIT executions and analyzed to obtain the required uncertainty parameters for the history-matching exercise. Polymer preshearing was considered as part of both PIT programs with the aim to homogenize the polymer molecular weight distribution and reduce possible shear-thickening effects near the wellbore as per laboratory measurements. Two single-well 3D simulation models were built to incorporate the information from polymer laboratory studies and to interpret the large field data sets acquired during the PITs. Lessons learned from PIT 1 allowed us to optimize the PIT 2 design program and achieve better understanding of polymer characteristics. The interpretation of the pressure transient analysis (PTA) of the PFO tests and the 3D simulation models of the two PITs confirmed the generation of polymer banks and demonstrated effective propagation of the polymer into the reservoirs at target concentrations and representative rates of the future SIWAP and SIMGAP interwell pilots.

Hydrogen bonding-regulated miscibility of graphene oxide and nonionic water-soluble polymers.

The integration of graphene and nonionic water-soluble polymers has generated useful composites with high performances and rich functionalities. These attractive graphene composites are usually synthesized from the aqueous mixture of graphene oxide (GO) precursor and polymers such as synthetic polyvinyl alcohol and natural cellulose. In this widely known preparation method, the miscibility of GO and nonionic water-soluble polymers seems to be intuitive but has been disputed by some observations of gelation and aggregation. Herein, we have re-examined the miscibility of GO and nonionic water-soluble polymers and confirm their general coaggregation caused by hydrogen bonding interaction. Due to the increasing GO concentration, the property of stable miscibility is converted to aggregation by surface adsorption with transient hydrogen bond crosslinking. We have proposed a preheat mixing strategy to prepare a homogenous solution of GO and nonionic water-soluble polymers in any arbitrary ratio. The re-exploited miscibility allows the fabrication of homogeneous composite papers with renewed high performance trend. The hydrogen bonding-regulated miscibility refreshes the understanding on graphene/water-soluble polymeric composites and provides an ecofriendly interaction control method to modulate the assembly of structures and materials.

Controlling conjugated polymer morphology by precise oxygen position in single-ether side chains.

Recently, polar side chains have emerged as a functional tool to enhance conjugated polymer doping properties by improving the polymer miscibility with polar chemical dopants and facilitate solvated ion uptake. In this work, we design and investigate a novel family of side chains containing a single ether function, enabling the modulation of the oxygen atom position along the side chain. A meticulous investigation of this new polymer series by differential scanning calorimetry, fast scanning chip calorimetry and X-ray scattering shows that polymers bearing single-ether side chains can show high degree of crystallinity under proper conditions. Importantly, due to a gauche effect allowing the side chain to bend at the oxygen atom, the degree of crystallinity of polymers can be controlled by the position of the oxygen atom along the side chain. The further the oxygen atom is from the conjugated backbone, the more crystalline the polymer becomes. In addition, for all new polymers, high thermomechanical properties are demonstrated, leading to remarkable electrical conductivities and thermoelectric power factors in rub-aligned and sequentially doped thin films. This work confirms the potential of single-ether side chains to be used as polar solubilizing side chains for the design of a next generation of p- and n-type semiconducting polymers with increased affinity to polar dopants while maintaining high molecular order.

Comparison of the Interaction and Structure of Lignin in Pure Systems and in Asphalt Media by Molecular Dynamics Simulations.

Lignin is a class of organic aromatic polymers contributing to the rigidity and strength of plants and has been proposed as a modifier to improve asphalt performance on road pavement. However, contradicting experimental results on the lignin miscibility in asphalt were found from different studies, and lignin has been found to self-assemble in different solutions. Thus, investigating the interaction and microstructure of lignin in asphalt media in molecular detail is necessary. Molecular dynamics (MD) simulations using both the LAMMPS program with the OPLS-aa force field and the NAMD program with the CHARMM force field have been conducted on pure lignin (including lignin monomer, dimer, and polymer with 17 and 31 units) and their mixtures with model asphalt molecules at different temperatures. Consistent results were observed from both programs and force fields in terms of density, hydrogen bonds, diffusion coefficient, radius of gyration, and radial distribution function. Glass transition was observed in the pure lignin systems based on density and diffusion coefficient calculations at different temperatures. Lignin can form intramolecular hydrogen bonds and intermolecular hydrogen bonds with other lignin and 1,7-dimethylnapthalene in the asphalt mixture, which has dependence on temperature and lignin chain length. Correlating the lignin size and chain length using the power-law relationship showed that lignin polymers in pure systems are in quasi-relaxed structures at different temperatures; lignin molecules stay in quasi-relaxed structures in asphalt mixtures at high temperatures but in collapsed structures at low temperatures. Implementing lignin monomer, dimer, and polymer into the model asphalt mixture can improve its density. Although lignin in different chain lengths aggregates in asphalt, lignin can modify the packing between different components in asphalt media at different temperatures. The work suggests that temperature can significantly influence the miscibility of lignin polymer in asphalt and that lignin can function as both a modifier and a resin in asphalt.

Interphase of polyoctenamer‐single‐wall carbon nanotubes by thermogravimetric analysis in air

AbstractNon‐isothermal thermogravimetric analysis in air, of polyoctenamer‐single wall carbon nanotubes (PO‐SWNTs), loaded by various amounts of SWNTs up to 10% wt., at different heating rates (ranging from 5 to 40°C/min) is reported. The thermal degradation in the air of PO_SWNTs is dominated by a main single sigmoidal dependence, assigned to the polymer and eventually polymer‐nanofiller interphase, over which a weaker sigmoid assigned to the thermo‐oxidative degradation of the nanofiller is superimposed at higher temperatures. The temperature at which the nanocomposite's residual mass fraction reaches x% wt. of the initial mass, Tx%, is reported (for x = 5, 50, and 85). The dependence of Tx% on the heating rate and the loading by nanotubes is analyzed. The temperature derivative of the thermograms defines new parameters (inflection residual mass fraction and inflection temperature) and (degradation) width. Their dependence on the loading by SWNTs was reported. Estimation of the interphase in polymer‐based nanocomposites is based on the postulate that the dependence of the inflection temperature on the composition of the nanocomposite obeys a Fox‐like dependence, where the bulk polymer and the polymer trapped within the interphase are considered as a blend of two miscible polymers. Complementary Raman, x‐ray diffraction, and differential scanning calorimetry support these results.

Phase separation phenomena in gelatin-glucose syrup mixtures: Microstructures and gel characterization

This study delves into phase separation phenomena occurring within gelatin-glucose syrup (GS) mixtures, focusing on compositions ranging from 6 to 10% gelatin and 40–60% GS. The investigation employed 250 Bloom gelatins with distinct properties and GS with varying dextrose equivalence (DE). Microstructural analyses of mixtures were conducted using inverted fluorescent microscopy both immediately after blending at 80 °C and following a 24-h incubation at different temperatures. Visual observation as well as rheological, thermal and textural analyses were employed to monitor bulk phase separation occurring at 45 and 60 °C and gel properties upon cooling. Upon mixing, a diverse range of morphologies emerged, ranging from single-phase configurations to bicontinuous, protein-in-polysaccharide, and polysaccharide-in-protein arrangements, which was attributed to the immiscibility between gelatin and the DP10+ polysaccharides in the GS beyond a concentration threshold and potentially driven by the molecular ordering of gelatin and the shear forces during mixing. The miscibility of polymers and the nature of continuous phase were markedly influenced by the dosage and properties of gelatin (MW and pI) and GS (DE). During incubation at 60 or 45 °C, structural rearrangement occurred, with certain compositions undergoing substantial bulk separation. Rapid cooling effectively arrested the initial microstructures, giving rise to the formation of turbid gel networks. Comparative analysis of the gel properties indicated that GS generally promoted the formation of gelatin gels, but excessive addition of low DE GS proved counterproductive to proper gel development, resulting in the formation of soft, weakly structured gels prone to syneresis or even outright nongelation.

Eco-Friendly Cellulose-Based Nonionic Antimicrobial Polymers with Excellent Biocompatibility, Nonleachability, and Polymer Miscibility.

This study aims to prepare natural biomass-based nonionic antimicrobial polymers with excellent biocompatibility, nonleachability, antimicrobial activity, and polymer miscibility. Two new cellulose-based nonionic antimicrobial polymers (MIPA and MICA) containing many terminal indole groups were synthesized using a sustainable one-pot method. The structures and properties of the nonionic antimicrobial polymers were characterized using nuclear magnetic resonance hydrogen spectroscopy (1H NMR), infrared spectroscopy (FTIR), wide-angle X-ray diffractometry (XRD), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), gel chromatography (GPC), and other analytical techniques. The results showed that microcrystalline cellulose (MCC) molecules combined with indole derivatives through an esterification reaction to produce MICA and MIPA. The crystallinity of the prepared MICA and MIPA molecules decreased after MCC modification; their morphological structure changed from short fibrous to granular and showed better thermal stability and solubility. The paper diffusion method showed that both nonionic polymers had good bactericidal effects against the two common pathogenic bacteria Escherichia coli (E. coli, inhibition zone diameters >22 mm) and Staphylococcus aureus (S. aureus, inhibition zone diameters >38 mm). Moreover, MICA and MIPA showed good miscibility with biodegradable poly(vinyl alcohol) (PVA), and the miscible cellulose-based composite films (PVA-MICA and PVA-MIPA) showed good phase compatibility, light transmission, thermal stability (maximum thermal decomposition temperature >300 °C), biocompatibility, biological cell activity (no cytotoxicity), nonleachability, antimicrobial activity, and mechanical properties (maximum fracture elongation at >390%).

Evaluation of the effects of zein incorporation on physical, mechanical, and biological properties of polyhydroxybutyrate electrospun scaffold for bone tissue engineering applications

Materials and fabrication methods significantly influence the scaffold's final features in tissue engineering. This study aimed to blend zein with polyhydroxybutyrate (PHB) at 5, 10, and 15 wt%, fabricate scaffolds using electrospinning, and then characterize them. SEM and mechanical analyses identified the scaffold with 10 wt% zein (PHB-10Z) as the optimal sample. Incorporating 10 wt% zein reduced fiber diameter from 894 ± 122 to 531 ± 42 nm while increasing ultimate tensile strength and elongation at break by approximately 53 % and 70 %, respectively. FTIR proved zein's presence in the scaffolds and possible hydrogen bonding with PHB. TGA confirmed the miscibility of polymers. DSC and XRD analyses indicated lower crystallinity for the PHB-10Z than for PHB. AFM evaluation indicated a rougher surface for the PHB-10Z in comparison to PHB. The PHB-10Z demonstrated a more hydrophobic surface and less weight loss after 100 days of degradation in PBS than PHB. The free radical scavenging assay exhibited antioxidant activity for the zein-containing scaffold. Eventually, enhanced cell attachment, viability, and differentiation in the PHB-10Z scaffold drawn from SEM, MTT, ALP activity, and Alizarin red staining of MG-63 cells confirmed that PHB-zein electrospun scaffold is a potent candidate for bone tissue engineering applications.

In vitro release study of electrospun poly(ε-caprolactone)/gelatin nanofiber mats loaded with 5-fluorouracil

The electrospinning process was used to successfully encapsulate an anticancer drug, 5-fluorouracil (5-FU), into poly(ε-caprolactone)/gelatin (Gel) nanofiber mats (5-FU-PCL/Gel NFs). Nanofibers are recognized to be potential carriers for the delivery of anticancer drugs. One of the safest solvent systems for making PCL/Gel NF mats is the formic acid/acetic acid (FA/AA) solvent system. A compound solution jet was drawn from a customized coaxial spinneret using a high potential electric field of 20 kV. The loading of 5-FU with three different concentrations (5, 10, and 15 wt.%) improved PCL stabilization in the FA/AA system. The miscibility of the blended polymers in the electrospun nanofibers mats and 5-FU being well distributed in the nanofiber matrix was investigated using X-ray diffraction (XRD). In vitro 5-FU release from electrospun PCL/Gel NF mats revealed sustained release from the nanofiber mats, whereas slower release was found when higher concentrations of 5-FU were used. The produced electrospun PCL/Gel NF mats were studied by SEM, FTIR, TGA, and DSC. According to a study on drug release kinetics, 5-FU was released from PCl/Gel NFs in a diffusion-controlled pattern.

Polymeric amorphous dispersion as a carrier to enhance the in vitro dissolution in vivo pharmacokinetics and cytotoxicity of niclosamide

AbstractAmorphous solid dispersion is one of the recent technologies that attracted the pharmaceutical industry to deliver poorly soluble drugs. However, the selection of polymeric carriers and characterization of drug‐polymer interactions need to be performed systemically to develop a stable amorphous delivery system. Solubility parameter analysis was used to screen the polymers. Hot melt extrusion (HME) was used to prepare the polymeric amorphous dispersion. Drug polymer interactions were identified by attenuated total reflection spectroscopy. Solid‐state transformations were characterized by differential scanning calorimetry and powder X‐ray diffraction. In vitro drug release was performed under non‐sink conditions. In vivo pharmacokinetic studies were performed on rats, and MCF‐7 and A‐549 cell lines were used to study the cytotoxicity. Polymer miscibility studies indicated polyvinylpyrrolidone (PVPK17) as a suitable polymer, and 180°C at 50 rpm was the ideal condition in the HME. The analytical tools confirmed the conversion of niclosamide (NCL) to an amorphous state and the existence of hydrogen bond interactions between the drug and the polymer. Prepared solid dispersions were stable for 3 months and showed about 214‐fold improvement in solubility and around 10‐fold improvement in dissolution over pure crystalline NCL. Pharmacokinetic studies showed a 4.04‐fold enhancement in Cmax and a 2.05‐fold enhancement in the area under the plasma concentration‐time curve (AUC0‐24h) compared to crystalline NCL. Cytotoxicity studies also showed a better toxicity profile with a reduction in the IC50 values of NCL in the amorphous solid dispersions. These encouraging findings indicate that polymeric amorphous solid dispersions could be a commercially feasible option to deliver poorly soluble drugs like NCL using HME.

Automatically Predicting Material Properties with Microscopic Images: Polymer Miscibility as an Example.

Many material properties are manifested in the morphological appearance and characterized using microscopic images, such as scanning electron microscopy (SEM). Polymer miscibility is a key physical quantity of polymer materials and is commonly and intuitively judged using SEM images. However, human observation and judgment of the images is time-consuming, labor-intensive, and hard to be quantified. Computer image recognition with machine learning methods can make up for the defects of artificial judging, giving accurate and quantitative judgment. We achieve automatic miscibility recognition utilizing a convolutional neural network and transfer learning methods, and the model obtains up to 94% accuracy. We also put forward a quantitative criterion for polymer miscibility with this model. The proposed method can be widely applied to the quantitative characterization of the microstructure and properties of various materials.

Superior ductile poly(glycolic acid)/poly(butylene adipate-co-terephthalate) blends compatibilized by triphenyl phosphite

Present study was aimed at exploring the compatibilization of poly(glycolic acid)/ poly(butylene adipate-co-terephthalate) (PGA/PBAT) blend in the presence of triphenyl phosphite (TPP) to prepare the ductile blend. The chain extension was monitored by the change torque value, which consisted with rheological behavior, that is, the increased TPP content led to an enhancement of melt strength for PGA/PBAT. TPP acted as a bridge to generate PGA-g-PBAT copolymer, promoting the interfacial interaction and miscibility of polymers. After being reactively compatibilized by 3 wt% TPP, the elongation at break, notched impact strength, and fracture toughness of the modified blend were increased by 627%, 60%, and 583% respectively. The morphology of impact-fractured surface revealed that the size of PBAT particles decreased from 2.05 µm to 1.35 µm with 3 wt% of TPP. The compatibilized blend with ductile feature was attributed to the interfacial debonding appending the fibrillation. Furthermore, when the content of TPP reached 5 wt%, the promoted chain entanglement led to a reduction of ductility. This work provided a facile strategy for the preparation of ductile PGA/PBAT blend.

Designing Sustainable Polymer Blends: Tailoring Mechanical Properties and Degradation Behaviour in PHB/PLA/PCL Blends in a Seawater Environment

Biodegradable polyesters are a popular choice for both packaging and medical device manufacture owing to their ability to break down into harmless components once they have completed their function. However, commonly used polyesters such as poly(hydroxybutyrate) (PHB), poly(lactic acid) (PLA), and polycaprolactone (PCL), while readily available and have a relatively low price compared to other biodegradable polyesters, do not meet the degradation profiles required for many applications. As such, this study aimed to determine if the mechanical and degradation properties of biodegradable polymers could be tailored by blending different polymers. The seawater degradation mechanisms were evaluated, revealing surface erosion and bulk degradation in the blends. The extent of degradation was found to be dependent on the specific chemical composition of the polymer and the blend ratio, with degradation occurring via hydrolytic, enzymatic, oxidative, or physical pathways. PLA presents the highest tensile strength (67 MPa); the addition of PHB and PCL increased the flexibility of the samples; however, the tensile strength reduced to 25.5 and 18 MPa for the blends 30/50/20 and 50/25/25, respectively. Additionally, PCL presented weight loss of up to 10 wt.% and PHB of up to 6 wt.%; the seawater degradation in the blends occurs by bulk and surface erosion. The blending process facilitated the flexibility of the blends, enabling their use in diverse industrial applications such as medical devices and packaging. The proposed methodology produced biodegradable blends with tailored properties within a seawater environment. Additionally, further tests that fully track the biodegradation process should be put in place; incorporating compatibilizers might promote the miscibility of different polymers, improving their mechanical properties and biodegradability.

Biodegradable Cellulose/Polycaprolactone/Keratin/Calcium Carbonate Mulch Films Prepared in Imidazolium-Based Ionic Liquid.

Ionic liquid 1-butyl-3-methylimidazolium chloride [BMIM][Cl] was used to prepare cellulose (CELL), cellulose/polycaprolactone (CELL/PCL), cellulose/polycaprolactone/keratin (CELL/PCL/KER), and cellulose/polycaprolactone/keratin/ground calcium carbonate (CELL/PCL/KER/GCC) biodegradable mulch films. Attenuated Total Reflectance Fourier-Transform Infrared (ATR-FTIR) spectroscopy, optical microscopy, and Field-Emission Scanning Electron Microscopy (FE-SEM) were used to verify the films' surface chemistry and morphology. Mulch film made of only cellulose regenerated from ionic liquid solution exhibited the highest tensile strength (75.3 ± 2.1 MPa) and modulus of elasticity of 944.4 ± 2.0 MPa. Among samples containing PCL, CELL/PCL/KER/GCC is characterized by the highest tensile strength (15.8 ± 0.4 MPa) and modulus of elasticity (687.5 ± 16.6 MPa). The film's breaking strain decreased for all samples containing PCL upon the addition of KER and KER/GCC. The melting temperature of pure PCL is 62.3 °C, whereas that of CELL/PCL film has a slight tendency for melting point depression (61.0 °C), which is a characteristic of partially miscible polymer blends. Furthermore, Differential Scanning Calorimetry (DSC) analysis revealed that the addition of KER or KER/GCC to CELL/PCL films resulted in an increment in melting temperature from 61.0 to 62.6 and 68.9 °C and an improvement in sample crystallinity by 2.2 and 3.0 times, respectively. The light transmittance of all studied samples was greater than 60%. The reported method for mulch film preparation is green and recyclable ([BMIM][Cl] can be recovered), and the inclusion of KER derived by extraction from waste chicken feathers enables conversion to organic biofertilizer. The findings of this study contribute to sustainable agriculture by providing nutrients that enhance the growth rate of plants, and hence food production, while reducing environmental pressure. The addition of GCC furthermore provides a source of Ca2+ for plant micronutrition and a supplementary control of soil pH.