Exploring the Future of Polyhydroxyalkanoate Composites with Organic Fillers: A Review of Challenges and Opportunities.

Biopolymers from renewable materials are promising alternatives to the traditional petroleum-based plastics used today, although they face limitations in terms of performance and processability. Natural fillers have been identified as a strategic route to create sustainable composites, and natural fillers in the form of waste by-products have received particular attention. Consequently, the primary focus of this article is to offer a broad overview of recent breakthroughs in environmentally friendly Polhydroxyalkanoate (PHA) polymers and their composites. PHAs are aliphatic polyesters obtained by bacterial fermentation of sugars and fatty acids and are considered to play a key role in addressing sustainability challenges to replace traditional plastics in various industrial sectors. Moreover, the article examines the potential of biodegradable polymers and polymer composites, with a specific emphasis on natural composite materials, current trends, and future market prospects. Increased environmental concerns are driving discussions on the importance of integrating biodegradable materials with natural fillers in our daily use, emphasizing the need for clear frameworks and economic incentives to support the use of these materials. Finally, it highlights the indispensable need for ongoing research and development efforts to address environmental challenges in the polymer sector, reflecting a growing interest in sustainable materials across all industries.

Specific Condis Crystal-like Mesophase of Poly(butylene succinate-co-butylene adipate).

Understanding the properties of polymers, such as their crystallinity, is crucial for their material performance and predicting their behavior during and after use, especially in the case of environmentally friendly (bio)degradable polymers, enabling optimized design. In this work, for the first time, a pressure-induced condis crystal-like mesophase of poly(butylene succinate-co-butylene adipate) (PBSA) is presented. The phase behavior of pressed films obtained from commercial PBSA with 25% butylene adipate units is investigated at various processing temperatures from room temperature to 100 °C, pressed at a pressure of the press jaws and at 2-5 t for 1-5 min. The characterization and quantification evaluation of the condis crystal-like mesophase of pressed PBSA formed at temperatures above the glass transition is investigated by X-ray diffraction, polarized optical microscopy (POM), and differential scanning calorimetry (DSC) methods. Our results demonstrate that pressed PBSA films at 60 °C show a condis crystal-like mesophase, characterized by the presence of reflections at wide angles, birefringence by POM, as well as a higher melting point (endotherm) by DSC. The resulting oriented mesomorphic green polymer can, in a sustainable manner, expand further technological applications of (bio)degradable polymers, especially in the medical field, and open up opportunities for further research that could provide such polymers with tailored persistence and degradation, thus changing the shelf life.

Towards scalable and degradable bioplastic films from Moringa oleifera gum/poly(vinyl alcohol) as packaging material.

The use of plant gum-based biodegradable bioplastic films as a packaging material is limited due to their poor physicochemical properties. However, combining plant gum with synthetic degradable polymer and some additives can improve these properties. Keeping in view, the present study aimed to synthesize a series of bioplastic films using Moringa oleifera gum, polyvinyl alcohol, glycerol, and citric acid via thermal treatment followed by a solution casting method. The films were characterized using analytical techniques such as FTIR, XRD, SEM, AFM, TGA, and DSC. The study examined properties such as water sensitivity, gas barrier attributes, tensile strength, the shelf life of food, and biodegradability. The films containing higher citric acid amounts showed appreciable %elongation without compromising tensile strength, good oxygen barrier properties, and biodegradation rates (>95%). Varying the amounts of glycerol and citric acid in the films broadened their physicochemical properties ranging from hydrophilicity to hydrophobicity and rigidity to flexibility. As all the films were synthesized using economical and environmentally safe materials, and showed better physicochemical and barrier properties, this study suggests that these bioplastic films can prove to be a potential alternative for various packaging applications.

Oligopeptide-based molecular labelling of (bio)degradable polyester biomaterials.

Nowadays, a very important motivation for the development of new functional materials for medical purposes is not only their performance but also whether they are environmentally friendly. In recent years, there has been a growing interest in the possibility of labelling (bio)degradable polymers, in particular those intended for specific applications, especially in the medical sector, and the potential of information storage in such polymers, making it possible, for example, to track the ultimate environmental fate of plastics. This article presents a straightforward green approach that combines both aspects using an oligopeptide, which is an integral part of polymer material, to store binary information in a physical mixture of polymer and oligopeptide. In the proposed procedure the year of production of polymer films made of poly(l-lactide) (PLLA) and a blend of poly(1,4-butylene adipate-co-1,4-butylene terephthalate) and polylactide (PBAT/PLA) were encoded as the sequence of the appropriate amino acids in the oligopeptide (PEP) added to these polymers. The decoding of the recorded information was carried out using mass spectrometry technique as a new method of decoding, which enabled the successful retrieval and reading of the stored information. Furthermore, the properties of labelled (bio)degradable polymer films and stability during biodegradation of PLLA/PEP film under industrial composting conditions have been investigated. The labelled films exhibited good oligopeptide stability, allowing the recorded information to be retrieved from a green polymer/oligopeptide system before and after biodegradation. The MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide assay) study of the PLLA and PLLA/PBAT using the MRC-5 mammalian fibroblasts was presented for the first time.

Bioconversion Process of Polyethylene from Waste Tetra Pak® Packaging to Polyhydroxyalkanoates.

Presented herein are the results of a novel recycling method for waste Tetra Pak® packaging materials. The polyethylene (PE-T) component of this packaging material, obtained via a separation process using a "solvents method", was used as a carbon source for the biosynthesis of polyhydroxyalkanoates (PHAs) by the bacterial strain Cupriavidus necator H16. Bacteria were grown for 48-72 h, at 30 °C, in TSB (nitrogen-rich) or BSM (nitrogen-limited) media supplemented with PE-T. Growth was monitored by viable counting. It was demonstrated that C. necator utilised PE-T in both growth media, but was only able to accumulate 40% w/w PHA in TSB supplemented with PE-T. Only 1.5% w/w PHA was accumulated in the TSB control, and no PHA was detected in the BSM control. Extracted biopolymers were characterised by nuclear magnetic resonance (NMR), Fourier-transform infrared (FTIR) spectroscopy, electrospray tandem mass spectrometry (ESI-MS/MS), gel permeation chromatography (GPC), and accelerator mass spectrometry (AMS). The characterisation of PHA by ESI-MS/MS revealed that PHA produced by C. necator in TSB supplemented with PE-T contained 3-hydroxybutyrate, 3-hydroxyvalerate, and 3-hydroxyhexanoate co-monomeric units. AMS analysis also confirmed the presence of 96.73% modern carbon and 3.27% old carbon in PHA derived from Tetra Pak®. Thus, this study demonstrates the feasibility of our proposed recycling method for waste Tetra Pak® packaging materials, alongside its potential for producing value-added PHA, and the ability of 14C analysis in validating this bioconversion process.

Nematic-to-Isotropic Phase Transition in Poly(L-Lactide) with Addition of Cyclodextrin during Abiotic Degradation Study.

Poly(L-lactide) is capable of self-assembly into a nematic mesophase under the influence of temperature and mechanical stresses. Therefore, subsequent poly(L-lactide) films were obtained and characterized, showing nematic liquid crystal properties both before and after degradation. Herein, we present that, by introducing ß-cyclodextrin into the polymer matrix, it is possible to obtain a chiral nematic mesophase during pressing, regardless of temperature and time. The obtained poly(L-lactide) films exhibiting liquid crystal properties were subjected to degradation tests and the influence of degradation on these properties was determined. Thermotropic phase behavior was investigated using polarized optical microscopy, X-ray diffraction, and differential scanning calorimetry. The degradation process demonstrated an influence on the liquid crystal properties of pressed polymer films. The colored planar texture of the chiral nematic mesophase, which was not observed prior to degradation in films without the addition of ß-cyclodextrin, appeared after incubation in water as a result of the entrapment of degradation products in the polymer matrix. These unusual tailor-made properties, obtained in liquid crystals in (bio)degradable polymers using a simple method, demonstrate the potential for advanced photonic applications.

Poly(l-Lactide) Liquid Crystals with Tailor-Made Properties Toward a Specific Nematic Mesophase Texture.

This paper presents the liquid crystal (LC) properties of poly(l-lactide) (PLLA). Mesophase behavior is investigated using polarized optical microscopy, X-ray diffraction, and differential scanning calorimetry. The performed analyses confirm that pressed PLLA films exhibit the unique capability of self-assembling into a nematic mesophase under the influence of mechanical pressure, temperature, and time. It was originally demonstrated that the chiral nematic mesophase can be obtained by introducing fine powders into the polymer. Based on the research conducted, it was proved that the pressed PLLA films have a chiral nematic mesophase with a nematic-to-isotropic phase transition and a large mesophase stability range overlapping the temperature of the human body, which can persist for years at ambient temperature. The obtained films show tailor-made properties toward a nematic mesophase with a specific texture, including colored planar texture of the chiral nematic mesophase and blue-phase (BP) LC texture. The BP, described for the first time in plain PLLA, occurred over a wider than usual temperature range of stability between isotropic and chiral nematic thermotropic phases (ΔT ≈ 9 °C), which is an advantage of the obtained polymer material, in addition to ease of preparation. This opens up new prospects for advanced photonic green applications.

Towards Advances in Molecular Understanding of Boric Acid Biocatalyzed Ring-Opening (Co)Polymerization of δ-Valerolactone in the Presence of Ethylene Glycol as an Initiator.

Following our previous studies on the molecular level structure of (co)oligoesters obtained via anionic homo- and co-polymerization of novel ß-substituted ß-lactones, prepared by the atmospheric pressure carbonylation reaction of respective epoxides, the boric acid biocatalyzed ring-opening (co)polymerization of δ-valerolactone has been studied. As a co-monomer the 6-methy-ε-caprolactone, prepared by the one-pot oxidation of respective alcohol, and ethylene glycol as polymerization initiator were used. The obtained copolymers were characterized by 1H-NMR, GPC and ESI-MS, respectively in order to confirm their chemical structures and identity. Subsequently, tandem mass spectrometry (MS-MS studies) via collision-induced dissociation were utilized to characterize the fragmentation pattern. ESI-MS and NMR analyses confirmed the formation of random linear copolymer chains composed of different polyester repeat units. MS-MS experiments showed that fragmentation proceeds via ester bound cleavage along the (co)polyester chains. The innovative aspect of this contribution is related to the elaboration of the telechelic (co)polymers end-capped with hydroxyl end groups and well-defined molecular architectures, which could facilitate the development of new flexible macromolecular systems for potential biomedical applications.

Stimuli-Responsive Aliphatic Polycarbonate Nanocarriers for Tumor-Targeted Drug Delivery.

Nanoparticles based on amphiphilic copolymers with tunable physicochemical properties can be used to encapsulate delicate pharmaceutics while at the same time improving their solubility, stability, pharmacokinetic properties, reducing immune surveillance, or achieving tumor-targeting ability. Those nanocarriers based on biodegradable aliphatic polycarbonates are a particularly promising platform for drug delivery due to flexibility in the design and synthesis of appropriate monomers and copolymers. Current studies in this field focus on the design and the synthesis of new effective carriers of hydrophobic drugs and their release in a controlled manner by exogenous or endogenous factors in tumor-specific regions. Reactive groups present in aliphatic carbonate copolymers, undergo a reaction under the action of a stimulus: e.g., acidic hydrolysis, oxidation, reduction, etc. leading to changes in the morphology of nanoparticles. This allows the release of the drug in a highly controlled manner and induces a desired therapeutic outcome without damaging healthy tissues. The presented review summarizes the current advances in chemistry and methods for designing stimuli-responsive nanocarriers based on aliphatic polycarbonates for controlled drug delivery.

Effective Control against Broadleaf Weed Species Provided by Biodegradable PBAT/PLA Mulch Film Embedded with the Herbicide 2-Methyl-4-Chlorophenoxyacetic Acid (MCPA).

Biodegradable mulches are considered a promising alternative to polyethylene-based, nonbiodegradable mulch for sustainable agriculture. In the present study, a bioactive 2-methyl-4- cholorophenoxyacetic acid/poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (MCPA-PHBV) conjugate blended with biodegradable poly(butylene adipate-co-terephthalate/polylactide (PBAT/PLA) was developed and used as mulch under controlled condition greenhouse pot experiment with fava bean (Vicia faba) as the nontarget crop species. The objectives were to examine the effectiveness of sustained-release of MCPA herbicide from biodegradable mulch for broadleaf weed suppression and to assess any adverse effects of the herbicide on the nontarget species (fava bean). The energy-dispersive X-ray spectroscopy analysis (EDS) suggests that a substantial quantity of the herbicide was released from the biodegradable mulch which effectively killed the broadleaf weed species even at 1% MCPA concentration. However, the higher concentrations of the herbicide adversely affected several physiological parameters of fava bean growth and development. Stomatal conductance decreased, while leaf temperature subsequently rose (at MCPA concentrations 5, 7.5, and 10%). The quantum yield of the Photosystem II (PSII) indicates that the photosynthetic efficiency was also restricted at concentrations 7.5% and 10%. Evidently, this slow-release herbicide system worked efficiently for broadleaf weed control but at higher concentrations, resulted in adverse physiological effects on the nontarget crop species. This study has demonstrated that biodegradable mulches containing MCPA herbicide are able to effectively inhibit the growth of broad leaf weed species and may be of potential importance in a wide variety of horticultural and agricultural applications.

Polymeric Carriers for Delivery Systems in the Treatment of Chronic Periodontal Disease.

Periodontitis (PD) is a chronic inflammatory disease of periodontal tissues caused by pathogenic microorganisms and characterized by disruption of the tooth-supporting structures. Conventional drug administration pathways in periodontal disease treatment have many drawbacks such as poor biodistribution, low selectivity of the therapeutic effect, burst release of the drug, and damage to healthy cells. To overcome this limitation, controlled drug delivery systems have been developed as a potential method to address oral infectious disease ailments. The use of drug delivery devices proves to be an excellent auxiliary method in improving the quality and effectiveness in periodontitis treatment, which includes inaccessible periodontal pockets. This review explores the current state of knowledge regarding the applications of various polymer-based delivery systems such as hydrogels, liposomes, micro-, and nanoparticles in the treatment of chronic periodontal disease. Furthermore, to present a more comprehensive understanding of the difficulties concerning the treatment of PD, a brief description of the mechanism and development of the disease is outlined.

Three-Dimensional Printed PLA and PLA/PHA Dumbbell-Shaped Specimens: Material Defects and Their Impact on Degradation Behavior.

The use of (bio)degradable polymers, especially in medical applications, requires a proper understanding of their properties and behavior in various environments. Structural elements made of such polymers may be exposed to changing environmental conditions, which may cause defects. That is why it is so important to determine the effect of processing conditions on polymer properties and also their subsequent behavior during degradation. This paper presents original research on a specimen's damage during 70 days of hydrolytic degradation. During a standard hydrolytic degradation study of polylactide and polylactide/polyhydroxyalkanoate dumbbell-shaped specimens obtained by 3D printing with two different processing build directions, exhibited unexpected shrinkage phenomena in the last degradation series, representing approximately 50% of the length of the specimens irrespective of the printing direction. Therefore, the continuation of previous ex-ante research of advanced polymer materials is presented to identify any possible defects before they arise and to minimize the potential failures of novel polymer products during their use and also during degradation. Studies on the impact of a specific processing method, i.e., processing parameters and conditions, on the properties expressed in molar mass and thermal properties changes of specimens obtained by three-dimensional printing from polyester-based filaments, and in particular on the occurrence of unexpected shrinkage phenomena after post-processing heat treatment, are presented.

The Solvation of Ca2+ with Gas Phase Clusters of Alcohol Molecules.

A comprehensive examination of how the identity of an alcohol molecule can change the behavior of a solvated, alkaline earth dication has been undertaken. The metal dication of Ca2+ has been clustered with a range of different alcohols to form [Ca(ROH)n]2+ complexes, where n lies in the range 2-20. Following collisional activation via electron capture from nitrogen gas, complexes for n in the range 2-6 exhibit a switch in reaction product as a function of n. For low values, solvated CaOH+ is the dominant fragment, but as n increases beyond 4, this is displaced by the appearance of solvated CaOR+. A separate study of unimolecular metastable decay by [Ca(ROH)n]2+ complexes found evidence of charge separation to form CaOH+(ROH)n-1 + R+. For two isomers of butanol, the n = 3 complexes were found to follow parallel, but different metastable pathways: one leading to the appearance of CaOH+ and another that resulted in proton abstraction to form ROH2+. These differences have been attributed to the precursor complexes adopting geometries where one ROH molecule occupies a secondary solvation shell. Comparisons were made with a previous study of magnesium complexes; [Mg(ROH)n]2+ show that the difference in second ionization energy Mg+ (15.09 eV) as opposed to Ca+ (11.88 eV) influences behavior. A complex between Ca2+ and 1-chloroethanol is shown to favor the formation of CaCl+ as opposed to CaOH+ as a unimolecular charge separation product, which is attributed to differences in bond energy in the precursor molecule.

Molecular Level Structure of Biodegradable Poly(Delta-Valerolactone) Obtained in the Presence of Boric Acid.

In this study, low molecular weight poly(δ-valerolactone) (PVL) was synthesized through bulk-ring openings polymerization of δ-valerolactone with boric acid (B(OH)3) as a catalyst and benzyl alcohol (BnOH) as an initiator. The resulting homopolymer was characterized with the aid of nuclear magnetic resonance (NMR) and mass spectrometry (MS) techniques to gain further understanding of its molecular structure. The electrospray ionization mass spectrometry (ESI-MS) spectra of poly(δ-valerolactone) showed the presence of two types of homopolyester chains-one terminated by benzyl ester and hydroxyl end groups and one with carboxyl and hydroxyl end groups. Additionally, a small amount of cyclic PVL oligomers was identified. To confirm the structure of PVL oligomers obtained, fragmentation of sodium adducts of individual polyester molecules terminated by various end groups was explored in ESI-MSn by using collision induced dissociation (CID) techniques. The ESI-MSn analyses were conducted both in positive- and negative ion mode. The comparison of the fragmentation spectra obtained with proposed respective theoretical fragmentation pathways allowed the structure of the obtained oligomers to be established at the molecular level. Additionally, using matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS), it was proven that regardless of the degree of oligomerization, the resulting PVL samples were a mixture of two types of linear PVL oligomers differing in end groups and containing just a small amount of cyclic oligomers that tended to be not visible at higher molar masses.

Forensic Engineering of Advanced Polymeric Materials-Part V: Prediction Studies of Aliphatic⁻Aromatic Copolyester and Polylactide Commercial Blends in View of Potential Applications as Compostable Cosmetic Packages.

The main aim of the present study was to determine the behavior of the specimens from Ecovio, in the form of dumbbell-shaped samples and films, during degradation in selected cosmetic ingredients such as water and paraffin. The (bio)degradation test of the prototype cosmetic package (sachet) made from a PBAT (poly[(1,4-butylene adipate)-co-(1,4-butylene terephthalate)]) and PLA (polylactide) blend was investigated under industrial composting conditions, and compared with the sample behavior during incubation in cosmetic media at 70 °C. During the degradation tests, the changes of the samples were evaluated using optical microscopy, ¹H NMR (proton nuclear magnetic resonance) and GPC (gel permeation chromatography) techniques. The structures of the degradation products were investigated using ESI-MSn (mass spectrometry with electrospray ionization on positive and negative ions) analysis. The thermal properties of selected materials were determined by DSC (differential scanning calorimetry) and TGA (thermogravimetric analysis) analysis. It was concluded that the PBAT and PLA blend studied had a good stability during aging in cosmetic media, and could be recommended for long-shelf-life compostable packaging of cosmetics, especially with oily ingredients.

The solvation of Cu2+ with gas-phase clusters of water and ammonia.

A detailed study has been undertaken of the gas-phase chemistry of [Cu(H2O)N]2+ and [Cu(NH3)N]2+ complexes. Ion intensity distributions and fragmentation pathways (unimolecular and collision-induced) have been recorded for both complexes out as far as N=20. Unimolecular fragmentation is dominated by Coulomb explosion (separation into two single charged units) on the part of the smaller ions, but switches to neutral molecule loss for N>7. In contrast, collisional activation promotes extensive electron capture from the collision gas, with the appearance of particular singly charged fragment ions being sensitive to the size and composition of the precursor. The results show clear evidence of the unit [Cu(X)8]2+ being of special significance, and it is proposed that the hydrogen-bonded structure associated with this ion is responsible for stabilizing the dipositive charge on Cu2+ in aqueous solution.