The current impetus to develop bio-based polymers for greater sustainability and lower carbon footprint is necessitated due to the alarming depletion of fossil resources, concurrent global warming, and related environmental issues. This article reviews the development of polymeric blends based on bio-based polymers. The focus on bio-based polymers is due to their greater \'Sustainability factor\' as they are derived from renewable resources. The article delves into the synthesis of both conventional and highly biodegradable bio-based polymers, each crafted from feedstocks derived from nature\'s bounty. What sets this work apart is the exploration of blending existing bio-based polymers, culminating in the birth of entirely new materials. This review provides a comprehensive overview of the recent advancements in the development of bio-based polymeric blends, covering their synthesis, properties, applications, and potential contributions to a more sustainable future. Despite their potential benefits, bio-based materials face obstacles such as miscibility, processability issues and disparities in physical properties compared to conventional counterparts. The paper also discusses significance of compatibilizers, additives and future directions for the further advancement of these bio-based blends. While bio-based polymer blends hold promise for environmentally benign applications, many are still in the research phase. Ongoing research and technological innovations are driving the evolution of these blends as viable alternatives, but continued efforts are needed to ensure their successful integration into mainstream industrial practices. Concerted efforts from both researchers and industry stakeholders are essential to realize the full potential of bio-based polymers and accelerate their adoption on a global scale.
Sustainable versatility: Reduce fossil fuel dependency and decompose naturally.Challenges: Poor mechanical properties and scalability.Modification strategies: Blending improves properties for specific uses.Market potential: Good market potential, despite a commercialized gap.Research need: To address challenges and advance bio-based polymer technology.

In this study, the synthesis of poly(AVGVP) [where A-Alanine, V-Valine, G-Glycine, and P-Proline] is executed by the stepwise solution phase method. The interaction between Chitosan and synthetic polypentapeptide in blends was examined in the liquid and solid phases. Viscosity criteria that establish the total miscibility with Chitosan are the Δ[η]m, the intrinsic viscosity [η], Huggins coefficient [KH], by Garcia ΔB, α by Sun, and μ suggested by Chee, ΔK, and β buttressed by Jiang and Han. Besides, the results are corroborated in the solid phase by differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and X-ray diffraction (XRD). Miscibility in the blends led to higher thermal stability than that of pure polymers, according to thermogravimetric analysis (TGA). In vitro, studies offered the absence of cytotoxicity, and in vivo histopathological results advocated that the blend shows less inflammation and is more compact as against cotton gauge, evincing an enhanced healing environment and promising the possibility of use in wound therapeutic applications.

The quantum mechanics-aided COSMO-SAC activity coefficient model is applied and systematically examined for predicting the thermodynamic compatibility of drugs and polymers. The drug-polymer compatibility is a key aspect in the rational selection of optimal polymeric carriers for pharmaceutical amorphous solid dispersions (ASD) that enhance drug bioavailability. The drug-polymer compatibility is evaluated in terms of both solubility and miscibility, calculated using standard thermodynamic equilibrium relations based on the activity coefficients predicted by COSMO-SAC. As inherent to COSMO-SAC, our approach relies only on quantum-mechanically derived σ-profiles of the considered molecular species and involves no parameter fitting to experimental data. All σ-profiles used were determined in this work, with those of the polymers being derived from their shorter oligomers by replicating the properties of their central monomer unit(s). Quantitatively, COSMO-SAC achieved an overall average absolute deviation of 13% in weight fraction drug solubility predictions compared to experimental data. Qualitatively, COSMO-SAC correctly categorized different polymer types in terms of their compatibility with drugs and provided meaningful estimations of the amorphous-amorphous phase separation. Furthermore, we analyzed the sensitivity of the COSMO-SAC results for ASD to different model configurations and σ-profiles of polymers. In general, while the free volume and dispersion terms exerted a limited effect on predictions, the structures of oligomers used to produce σ-profiles of polymers appeared to be more important, especially in the case of strongly interacting polymers. Explanations for these observations are provided. COSMO-SAC proved to be an efficient method for compatibility prediction and polymer screening in ASD, particularly in terms of its performance-cost ratio, as it relies only on first-principles calculations for the considered molecular species. The open-source nature of both COSMO-SAC and the Python-based tool COSMOPharm, developed in this work for predicting the API-polymer thermodynamic compatibility, invites interested readers to explore and utilize this method for further research or assistance in the design of pharmaceutical formulations.

Salts of weakly basic drugs can partially dissociate in formulations, to give basic drugs and counter acids. The aim of the present study was to clarify the effect of physicochemical properties on the basic drug-acid-polymer interactions and salt-polymer miscibility, and to explain the influence mechanism at the molecular level. Six maleate salts with different physicochemical properties were selected and PVA was used as the film forming material. The relationship between the physicochemical properties and the miscibility was presented with multiple linear regression analysis. The existence state of salts in formulations were determined by XRD and Raman imaging. The stability of salts was characterized by NMR and XPS. The intermolecular interactions were investigated by FTIR and NMR. The results showed that the salt-PVA miscibility was related to polar surface area of salts and Tg of free bases, which represented hydrogen bond interaction and solubility potential. The basic drug-acid-PVA intermolecular interactions determined the existence state and bonding pattern of the three molecules. Meanwhile, the decrease of the stability after formulation increased the number of free bases in orodispersible films, which in turn affected the miscibility with PVA. The study provided references for the rational design of PVA based orodispersible films.

Polylactide/ethylene vinyl alcohol copolymer (PLA/EVOH) blends and fibers with different weight ratios were prepared by melt blending, and two-step melt spinning, respectively. PLA and EVOH in PLA/EVOH blends were immiscible. When EVOH content was ≤60 %, EVOH with the average diameter of about 3 μm was dispersed in PLA matrix uniformly. The dual continuous phases could be observed in PLA/EVOH blend with 70 wt% EVOH. When the EVOH content was ≥80 %, the spherical PLA phase with the diameter of 0.25 to 1 μm was dispersed in EVOH matrix. The introduction of EVOH as nucleating agent could promote the crystallization of PLA. Both PLA and EVOH components in PLA/EVOH blends formed individual crystal phases. The viscosity of PLA/EVOH blend with 5 % EVOH was lower than that of neat PLA. The viscosity of PLA/EVOH blends with the EVOH content of ≥10 % was much higher than that of neat PLA, which showed obvious shear thinning behavior. With the increase of EVOH content, the shear thinning behavior became obvious and the critical shear rate decreased gradually. The drawn PLA/EVOH fibers with the tensile strength of ≥16 cN/tex exhibited good mechanical properties. In addition, the introduction of EVOH could improve the hydrophilicity of PLA fibers.

All-polymer solar cells have experienced rapid development in recent years by the emergence of polymerized small molecular acceptors (PSMAs). However, the strong chain entanglements of polymer donors (PDs) and polymer acceptors (PAs) decrease the miscibility of the resulting polymer mixtures, making it challenging to optimize the blend morphology. Herein, we designed three PAs, namely PBTPICm-BDD, PBTPICγ-BDD and PBTPICF-BDD, by smartly using a BDD unit as the polymerized unit to copolymerize with different Y-typed non-fullerene small molecular acceptors (NF-SMAs), thus achieving a certain degree of distortion and giving the polymer system enough internal space to reduce the entanglements of the polymer chains. Such effects increase the chances of the PD being interspersed into the acceptor material, which improve the solubility between the PD and PA. The PBTPICγ-BDD and PBTPICF-BDD displayed better miscibility with PBQx-TCl, leading to a well optimized morphology. As a result, high power conversion efficiencies (PCEs) of 17.50 % and 17.17 % were achieved for PBQx-TCl : PBTPICγ-BDD and PBQx-TCl : PBTPICF-BDD devices, respectively. With the addition of PYFT-o as the third component into PBQx-TCl : PBTPICγ-BDD blend to further extend the absorption spectral coverage and finely tune microstructures of the blend morphology, a remarkable PCE of 18.64 % was realized finally.

The success of obtaining solid dispersions for solubility improvement invariably depends on the miscibility of the drug and polymeric carriers. This study aimed to categorize and select polymeric carriers via the classical group contribution method using the multivariate analysis of the calculated solubility parameter of RX-HCl. The total, partial, and derivate parameters for RX-HCl were calculated. The data were compared with the results of excipients (N = 36), and a hierarchical clustering analysis was further performed. Solid dispersions of selected polymers in different drug loads were produced using solvent casting and characterized via X-ray diffraction, infrared spectroscopy and scanning electron microscopy. RX-HCl presented a Hansen solubility parameter (HSP) of 23.52 MPa1/2. The exploratory analysis of HSP and relative energy difference (RED) elicited a classification for miscible (n = 11), partially miscible (n = 15), and immiscible (n = 10) combinations. The experimental validation followed by a principal component regression exhibited a significant correlation between the crystallinity reduction and calculated parameters, whereas the spectroscopic evaluation highlighted the hydrogen-bonding contribution towards amorphization. The systematic approach presented a high discrimination ability, contributing to optimal excipient selection for the obtention of solid solutions of RX-HCl.

Miscibility is critical in the prediction of stability against crystallization of amorphous solid dispersions (ASDs) in the solid state. However, currently available approaches for its determination are limited by both theoretical and practical considerations. Recently, a rheological approach guided by the polymer overlap concentration (c*) has been proposed for miscibility quantification of ASDs [J. Pharm. Sci., 112 (2023) 204-212] and shown to be useful in predicting both accelerated and long term physical stability in the absence of moisture. However, this approach can only be performed at high temperatures (slightly above the melting temperature, Tm, of drugs), and little is known about the difference in miscibility between high and low temperatures (e.g., below the glass transition temperature, Tg). Here we compare the miscibility of nifedipine (NIF)/polyvinylpyrrolidone (PVP) ASDs as determined by the rheological approach at 175°C (∼3°C above Tm of NIF) and solid state NMR (ssNMR) 1H T1 and T1ρ relaxation times at -20°C (∼66°C below Tg of NIF). Our results indicate agreement between the two methods. For low molecular weight (Mw) PVP, T1ρ measurements are more consistent with the rheological approach, while T1 measurements are closer for relatively high Mw PVP. Our findings support the use of the c* based rheological approach for inferring miscibility of deeply cooled ASDs.

Solid dispersions (SDs) have emerged as a promising strategy to enhance the solubility and bioavailability of poorly soluble active pharmaceutical ingredients. However, SDs tend to recrystallize unless suitable excipients are utilized. This study aimed to facilitate the rational selection of polymers and formulation design by evaluating the impact of various polymers on the miscibility, and phase behavior of SDs using baloxavir marboxil (BXM) with a high crystallization tendency as a model drug. Meanwhile, the effects of these polymers on the solubility enhancement and recrystallization inhibition were also assessed. The results indicated that the miscibility limit of BXM for HPMCAS was around 40 % drug loading (DL), whereas for PVP, PVPVA, and HPMC approximately 20 % DL. The BXM-HPC system exhibited limited miscibility with DL of 10 % or higher. BXM SDs based on various polymers exhibited varying degrees of spontaneous phase separation once DL exceeded the miscibility limit. Interestingly, a correlation was discovered between the phase separation behavior and the ability of the polymer to inhibit recrystallization. BXM-HPMCAS SDs exhibited optimal dissolution performance, compared with other systems. In conclusion, the physicochemical properties of polymers significantly influence BXM SDs performance and the BXM-HPMCAS SDs might promote an efficient and stable drug delivery system.

Although the active and intelligent properties of rich in anthocyanin extracts added to films have been extensively studied, there remains a sparsity of research pertaining to the miscibility of blended films. This work focused on the miscibility of the chitosan/polyvinyl alcohol (CP) film caused by the addition of Aronia melanocarpa extracts (AME), which are rich anthocyanins and phenolic acids, and its effect on physicochemical and functional properties. AME facilitated the amidation reaction and ionic interaction of chitosan in CP films, leading to loss of the crystallinity degree of chitosan. Furthermore, the crystal disruption promoted the formation of hydrogen bonds with polyvinyl alcohol (PVA) with the promoted miscibility. CP film incorporated with 8 % AME possessed the highest tensile strength (26.79 MPa), and elongation at break (66.38 %) as well as excellent ultraviolet-visible (UV-vis) light barrier property, water vapor barrier properties, due to its high miscibility degree. Moreover, this film also showed excellent antioxidant, antibacterial activity, and pH response function, which could be used to monitor the storage of highly perishable shrimp. Hence, the AME provided extra functionality and improved miscibility between chitosan and PVA, which showed great potential for the preparation of high-performance bioactive-fortified and intelligent food packaging films.