Marek Kowalczuk

Electrospray tandem mass spectrometry of poly(3-hydroxybutanoic acid) end groups analysis and fragmentation mechanism

The electrospray ionization tandem mass spectrometry technique applied for the first time to aliphatic polyester analysis, allowed fast and reliable identification of the various macromolecules of poly(3-hydroxybutanoic acid) (PHB), synthesized via ring-opening polymerization of β-butyrolactone. It was demonstrated that the biomimetic polymers studied contain various end groups, depending on the anionic initiator employed, and show close similarity to the natural PHB produced by enzymes in living cells of prokaryotic and eukaryotic organisms.

Study of Aliphatic-Aromatic Copolyester Degradation in Sandy Soil and Its Ecotoxicological Impact

Degradation of poly[(1,4-butylene terephthalate)-co-(1,4-butylene adipate)] (Ecoflex, BTA) monofilaments (rods) in standardized sandy soil was investigated. Changes in the microstructure and chemical composition distribution of the degraded BTA samples were evaluated and changes in the pH and salinity of postdegradation soil, as well as the soil phytotoxicity impact of the degradation products, are reported. A macroscopic and microscopic evaluation of the surface of BTA rod samples after specified periods of incubation in standardized soil indicated erosion of the surface of BTA rods starting from the fourth month of their incubation, with almost total disintegration of the incubated BTA material observed after 22 months. However, the weight loss after this period of time was about 50% and only a minor change in the M(w) of the investigated BTA samples was observed, along with a slight increase in the dispersity (from an initial 2.75 up to 4.00 after 22 months of sample incubation). The multidetector SEC and ESI-MS analysis indicated retention of aromatic chain fragments in the low molar mass fraction of the incubated sample. Phytotoxicity studies revealed no visible damage, such as necrosis and chlorosis, or other inhibitory effects, in the following plants: radish, cres, and monocotyledonous oat, indicating that the degradation products of the investigated BTA copolyester are harmless to the tested plants.

NOVEL SYNTHESIS OF FUNCTIONALIZED POLY(3-HYDROXYBUTANOIC ACID) AND ITS COPOLYMERS

Novel feasibility of fuctionalized poly(3-hydroxybutanoic acid), PHB, and its copolymers synthesis via ring-opening of beta-butyrolactone (ROP) mediated by activated anionic initiators or enzymes in vitro is presented. Using these new synthetic approaches, PHB with defined chemical structure of the end groups as well as block, graft and random copolymers have been obtained and characterized by IR, NMR, ESI-MS and GPC techniques. The relationship between the structure and properties of the novel polymeric materials prepared is discussed.

Anionic ring-opening polymerization of beta-alkoxymethyl-substituted beta-lactones.

We report on anionic ring-opening polymerization (ROP) of racemic beta-(methoxymethyl)-beta-propiolactone (MOMPL) and beta-(ethoxymethyl)-beta-propiolactone (EOMPL) initiated by supramolecular complex of potassium acetate and tetrabutylammonium acetate (Bu4N+ Ac) as well as by tetrabutylammonium hydroxide, respectively. Structure of the resulting polymers has been established at the molecular level by electrospray ionization multistage mass spectrometry (ESI-MS(n)) and has been confirmed by FT-IR, NMR, and GPC analyses. Similar behavior of MOMPL and EOMPL with respect to already-studied beta-alkyl-substituted beta-lactones, e.g., beta-butyrolactone (MPL), has been observed under the conditions of anionic ROP (including observed side reactions leading to unsaturated end groups) and the already-established mechanisms of anionic polymerization of beta-alkyl-substituted beta-lactones are extended on beta-alkoxymethyl-substituted ones.

Electrospray ionisation tandem mass spectrometry of poly [(R,S)-3-hydroxybutanoic acid] telechelics containing primary hydroxy end groups

Evaluation of polymer end-capping reactions with the aid of electrospray ionisation tandem mass spectrometry techniques (ESI-MS(n)) allows characterisation of novel poly[(R, S)-3-hydroxybutanoic acid]-(a-PHB) telechelics, containing primary hydroxyl groups at both polymer chain ends. The chemical structures of individual mass-selected macromolecules of the well-defined a-PHB telechelics have been defined in this way, and fragmentation mechanisms have been proposed. Copyright 1999 John Wiley & Sons, Ltd.

Carbon Sources for Polyhydroxyalkanoates and an Integrated Biorefinery

Polyhydroxyalkanoates (PHAs) are a group of bioplastics that have a wide range of applications. Extensive progress has been made in our understanding of PHAs’ biosynthesis, and currently, it is possible to engineer bacterial strains to produce PHAs with desired properties. The substrates for the fermentative production of PHAs are primarily derived from food-based carbon sources, raising concerns over the sustainability of their production in terms of their impact on food prices. This paper gives an overview of the current carbon sources used for PHA production and the methods used to transform these sources into fermentable forms. This allows us to identify the opportunities and restraints linked to future sustainable PHA production. Hemicellulose hydrolysates and crude glycerol are identified as two promising carbon sources for a sustainable production of PHAs. Hemicellulose hydrolysates and crude glycerol can be produced on a large scale during various second generation biofuels’ production. An integration of PHA production within a modern biorefinery is therefore proposed to produce biofuels and bioplastics simultaneously. This will create the potential to offset the production cost of biofuels and reduce the overall production cost of PHAs.

LC-multistage mass spectrometry for the characterization of poly(butylene adipate-co-butylene terephthalate) copolyester.

A comprehensive study using liquid chromatography electrospray ionization multistage mass spectrometry (LC-ESI MSn) was performed to get detailed structural information on poly(butylene adipate-co-butylene terephthalate) co-polyester and its product of partial degradation. LC-MS and LC-MSn identified the existence of cyclic structures in the original samples that disappear completely during the degradation. The occurrence of methanol transesterification in the degradation process was confirmed. MS2 on the first 13C isotope peak helped to determine the elemental composition of the fragments and facilitated end group determination. The method can be used to provide an alternative for high mass accuracy MS2 experiments. Sequence information was also revealed for certain copolymeric structures.

MALDI-TOF MS Reveals the Molecular Level Structures of Different Hydrophilic-Hydrophobic Polyether-esters

Multi- and triblock copolymers based on 1,5-dioxepan-2-one/epsilon-caprolactone (DXO/CL) were investigated by MALDI-TOF MS to determine the influence of copolymer composition and architecture on the molecular structures at the individual chain level. The copolymer compositions, average block lengths, and molecular weights were determined by (1)H and (13)C NMR and by SEC, respectively. The structures of polyether-ester oligomers (linear, cyclic) as well as the chemical structures of their end groups were established on the basis of their MALDI-TOF mass spectra. The mass spectrum of PDXO homopolymer was relatively simple, however, complex mass spectra were obtained in the case of multi- and triblock copolymers and the mass spectra clearly discerned the molecular level effect of copolymer composition and copolymer type.

Degradability of Poly(β-Hydroxybutyrate)s. Correlation with Chemical Microstructure

Abstract Poly(β-hydroxybutyrate)s (PHB) of different microstructures were synthesized via anionic polymerization of β-butyrolactone initiated by two initiators: 1) supramolecular complexes of alkali metals with asymmetric induction agents, and 2) alkali metal alkoxides. The relationships between chemical microstructure and hydrolytic as well as thermal degradation properties of synthetic and natural PHB are discussed.

Enzymatic synthesis of polyesters from hydroxyl acids

Abstract With porcine pancreatic lipase (PPL) as catalyst, aliphatic polyesters with hydroxyl and carboxyl end groups were synthesized through polycondensation of 3-hydroxybutyric acid (3-HBA) or 12-hydroxydodecanoic acid (12-HDA). The molecular weight ( M n , number average) of obtained polymers varies from several hundred to several thousand depending on monomer used and reaction conditions as well. Resultant polymers were characterized by IR, 1 H-NMR and GPC.