Zbigniew Jedliński

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.

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.

Polylactones 33. The role of deprotonation in the anionic polymerization of β-propiolactone

Abstract β-Propiolactone was reacted with triethylamine, pyridine, triphenylphosphine, potassium tert -butoxide, potassium (4- t -butylphenoxide) or potassium benzoate in CDCl 3 or dimethylsulfoxide in an n.m.r. tube. The 1 H n.m.r. analyses revealed in all cases formation of large amounts of acrylate groups. β-Propiolactone was polymerized at 20°C with triethylamine, pyridine or triphenylphosphine at a monomer/initiator ratio (M/I) of 50:1, and the endgroups of the isolated poly(β-propiolactone)s were characterized by 1 H- and 13 C-n.m.r. spectroscopy. Acrylate groups were found in all cases, even when the initiation with triphenylphosphine was conducted at −70°C. Sodium methoxide and potassium t -butoxide even attack polypropiolactone, yielding acrylate endgroups by deprotonation and elimination. In the presence of methanol, transesterification with formation of methyl ester endgroups also takes place. Only small amounts of acrylate groups were found when tributyltin methoxide served as initiator at 60–100°C. With aluminium isopropoxide acrylate endgroups were almost absent. Thus, the degree of deprotonation allows a differentiation between a true anionic polymerization and a nonionic insertion mechanism.

Si-H functional polysilanes via a homogeneous reductive coupling reaction

A polysilane copolymer with reactive Si-H side groups was obtained through a homogeeous coupling reaction of dichlorodiphenylsilane with dichloromethylsilane. The reaction was carried out in a tetrahydrofuran (THF) solution of a sodium-potasium alloy complex with 18-crown-6 with a well defined composition of alkali metal ion pairs (Mt + /crown ether, Mt ― ) at -75°C. The product was characterized using 1 H NMR, 13 C NMR, FT-IR and UV/Visible spectroscopies and gel permeation chromatography. The result were compared with those obtained by the heterogeneous coupling reaction of the same monomers.

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.

Synthesis of Potentially Biodegradable Polymers

Abstract Homopolymers of β-butyrolactone, L-lactide, δ-valerolactone, and methyl methacrylate, as well as their block copolymers, were prepared with simple initiator systems based on alkali metal alkoxides and alkali metal supramolecular complexes. The goal was to synthesize polymeric materials with potential biodegradability.

Investigation of the structure of poly(p-chlorophenyl glycidyl ether) by the 13C n.m.r. technique: tacticity and addition isomerism

Abstract The p -chlorophenyl glycidyl ether was polymerized in the presence of Al(OiPr) 3 , ZnCl 2 , SnCl 4 , BuOK, KOH and by the Al(OiPr) 3 ZnCl 2 1:1 initiator system. Analysis of the 13 C n.m.r. spectra of the poly( p -chlorophenyl glycidyl ethers) obtained has made it possible to determine their tacticity and the content of the head-to-tail and head-to-head linkages in the polymer chain.

Oxirane ring opening and polymer structure in the polymerization of styrene oxide initiated by aluminium isopropoxide

Abstract In the Al(OiPr)3 initiated polymerization of styrene oxide, a relatively high molecular weight, head-to-tail polymer is obtained with some oligomers. Study of the polymerization and model reactions of R(+)-styrene oxide initiated by Al(OiPr)3 indicates that, unlike the case of anionic polymerization, the oxirane ring is opened exclusively at the α-position (cleavage of the CHO-bond), a process which is accompanied by inversion of the configuration of the tertiary carbon atom.

Block/segmented polymer: 2. Studies on the thermal and mechanical properties of poly(amide ester)-ester copolymer

Abstract A new poly(amide ester)-ester copolymer was synthesized by reacting two oligomers, namely, oligo(amide ester) and oligo ester. Depending on the molar ratio of the two oligomers, a behavioural pattern of elastomeric to elastoplastic material was observed. D.s.c. studies revealed two glass transition temperatures: one at −40 to −50°C and another at 40 to 50°C, showing the presence of two different segments in the polymer backbone. Electron microscopic studies could not distinguish and differentiate the phase separation behaviour of the segments in the polymer. Mechanical studies showed that the polymer has a tensile strength at break of 6–20 MPa with an elongation as high as 160%.