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We report the synthesis and structural studies of oligo(3-hydroxybutyrate) conjugates with sorbic acid and benzoic acid, designed for food active packaging systems. The preservative–oligomer conjugates were obtained via the anionic ring-opening oligomerization of racemicβ-butyrolactone initiated by sodium sorbate and sodium benzoate, respectively. The structures of the resulting conjugates have been established at the molecular level by electrospray ionization multistage mass spectrometry in positive-ion mode supported by proton nuclear magnetic resonance. The fragmentation of the selected ions of the resulting conjugates confirmed that preservatives molecules, with unchanged structure, are covalently bonded to oligo(3-hydroxybutyrate). [ABSTRACT FROM PUBLISHER]

Autoimmune diseases result from the activation of self-reactive T cells recognizing autoantigens or foreign antigens cross-reactive with an autoantigen. T cells are thought to play a major role in autoimmune diseases in different organs, including the eye. This review focuses on the role of T cells in autoimmune uveitis in humans and in animal models of experimental autoimmune uveitis. Since rheumatoid arthritis is an autoimmune disease that has been studied far more extensively than uveitis, we have also included a review of clinical and experimental observations relevant to that disease. [ABSTRACT FROM AUTHOR]

The environmental impact of plastic usage is of critical concern and too great to repair. A shift toward biodegradable food packaging is one option. The aim of this review paper is the study of the potential of biodegradable materials for food packaging. The main characteristics in relation to food usage can be narrowed down to mass transfer (gas and water vapor), thermal and mechanical properties. Among several kinds of biodegradable polymers, poly(hydroxyalkanoate) is one of the favorable candidates for food packaging due to its physical and mechanical properties, biodegradability, with low permeability for O2, H2O and CO2 without residues of catalysts and water solubility. The main focus of this article is to address poly(hydroxyalkanoate) as a potential candidate for food packaging. The need of applying biobased polymers in food packaging is presented in the introduction of this study. We also describe the most common biopolymers providing a brief overview of classification and application. This is followed by an outline of biopolymer production and a main section in which the properties of poly(hydroxybutyrate)- based nanocomposites of greatest relevance to food packaging are discussed. Furthermore, several approaches for improvement of poly(hydroxybutyrate) properties are described and the role of nanotechnology to improve its mechanical properties is presented. Finally, the article concludes with a summary as well as some possible future trends. [ABSTRACT FROM AUTHOR]

The degradation of the advanced polymeric materials: blends of polylactide with poly[(R,S)-3-hydroxybutyrate] was studied in paraffin (an ingredient used in cosmetics) and compared with the degradation of pure poly[(R,S)-3-hydroxybutyrate]. The interaction between the polymeric materials studied and the paraffin was monitored during the degradation experiments, and the effects of this interaction were reported. Gel permeation chromatography, atomic force microscopy, electrospray mass spectrometry, nuclear magnetic resonance, differential scanning calorimetry and thermal gravimetric analysis revealed that degradation of the investigated materials occurs in the presence of paraffin. In the blends, poly[(R,S)-3-hydroxybutyrate] content was found to extend the disintegration time, and for the blends with good miscibility, reduced the degradation rate in the first step of degradation. [ABSTRACT FROM AUTHOR]

The reactions of (R,S) β-butyrolactone with L-alanine and related oligopeptides (Ala-Ala-Ala) were investigated. The resulting water-soluble oligomers were composed of poly[(R,S)-3-hydroxybutanoic acid] (a-PHB) covalently conjugated to L-alanine and Ala-Ala-Ala oligopeptide. The other chain end was of the carboxylic acid type. The structure of the obtained oligomers was assessed by electrospray ionization multistage mass spectrometry (ESI-MS[sup n]) and the respective structural information was completed by IR, NMR, and GPC analyses. The molecular weight and structure of the products could be controlled through reaction conditions. Using this new synthetic approach, a-PHB oligomers with well-defined end groups, as well as respective block copolymers, can be prepared via regioselective ring-opening oligomerization of (R,S)β-butyrolactone induced by amino acids under their zwitterionic form. [ABSTRACT FROM AUTHOR]

Application of new biodegradable polymer packaging based on polylactide (PLA), susceptible to organic recycling, can help in the waste reduction in landfills. In this paper, the results of the study on abiotic degradation of PLA and its blend containing 15 mol% of poly[( R , S )-3-hydroxybutyrate], as a model for the first step of organic recycling were presented. The samples used for this study have different shapes and thicknesses: rigid films and cuboid-bars. Particular emphasis was placed on determining the pattern of degradation products released into the medium. Originally, the results of present study revealed that the application of electrospray ionization mass spectrometry supported by high performance liquid chromatography allowed envisaging the differences in the degradation products pattern released from the studied PLA-based samples differing in thickness. The significant differences in degradation products pattern were predominately observed in the first steps of incubation process and are caused by an autocatalytic effect, which occurs mainly during degradation of the large size PLA samples. Although, the thickness of PLA-based packaging changes the degradation product patterns, however this does not increase the total amounts of acids released to the medium. Thus, it may be concluded that thickness should not affect significantly organic recycling of the packaging. [ABSTRACT FROM AUTHOR]

We report the synthesis and characterization of a novel polypyrrole material grafted with biodegradable oligo-3-hydroxybutyrate pendants. The polymer was prepared in a two-step process. Firstly, the potassium salt 1-(2-carboxyethyl)pyrrole was reacted with β-butyrolactone affording N-substituted macromonomer. Secondly, the macromonomer was oxidatively polymerised with FeCl Lewis acid. The reaction was carried out in solvents of assorted polarity: dimethylsulphoxide, acetonitrile, dimethylformamide and water. Obtained polymers have been characterised comprehensively using a suite of spectral techniques. The material was found to combine the well-known merits of 3-hydroxybutyrate polymers with the electrical conductivity imparted by polypyrrole units. [ABSTRACT FROM AUTHOR]

Abstract: Poly(l-lactide), PLLA, belongs to the most widely used biodegradable polyesters. These polymers have attracted great attention in recent years due to their excellent material properties, which give a rise to potential applications in various commercial areas. Previously, PLLA reprocessing in a co-rotating twin-screw extruder was used as a model test for material recycling. It may be assumed basing on this study, that PLLA technological wastes may be suitable for reuse, for example, as an additive for neat PLLA. In order to verify such suitability of reprocessed PLLA its degradability under industrial composting conditions was studied at the static composting open-air pile. Incubation of this material in water at 70 °C (abiotic conditions) was also conducted. The progress of the degradation process was monitored by surface changes and measurements of sample weight loss and changes in the PLLA molecular weight. The molecular level structure of the water soluble degradation products of PLLA samples was determined by electrospray ionization multistage mass spectrometry (ESI-MSn). Lactic acid and its oligomers terminated by hydroxyl and carboxyl end groups were identified as hydrolytic degradation products. The obtained results indicated that in selected environments (industrial composting and incubation under abiotic conditions) hydrolytic degradation via random ester bond scission occurs preferentially. It was demonstrated, that multi-reprocessing of PLLA did not significantly affect the rate of degradation and only slightly affected the disintegration progress of the PLLA samples. [Copyright &y& Elsevier]

Welding technology may be considered as a promising processing method for the formation of packaging products from biopolymers. However, the welding processes used can change the properties of the polymer materials, especially in the region of the weld. In this contribution, the impact of the welding process on the structure and properties of biopolymer welds and their ability to undergo hydrolytic degradation will be discussed. Samples for the study were made from polylactide (PLA) and poly(3-hydroxyalkanoate) (PHA) biopolymers which were welded using two methods: ultrasonic and heated tool welding. Differential scanning calorimetry (DSC) analysis showed slight changes in the thermal properties of the samples resulting from the processing and welding method used. The results of hydrolytic degradation indicated that welds of selected biopolymers started to degrade faster than unwelded parts of the samples. The structure of degradation products at the molecular level was confirmed using mass spectrometry. It was found that hydrolysis of the PLA and PHA welds occurs via the random ester bond cleavage and leads to the formation of PLA and PHA oligomers terminated by hydroxyl and carboxyl end groups, similarly to as previously observed for unwelded PLA and PHA-based materials. [ABSTRACT FROM AUTHOR]