Tadeusz Biela

Block and random copolymers of ε-caprolactone

Abstract Conditions of the living homopolymerization of e-caprolactone (CL), lactides (LA), and of the homo-oligomerization of γ-butyrolactone (BL) are briefly described. Then block and random copolymerizations of CL with LA are shortly reviewed. The microstructure of the resulting copolyesters in relation to some peculiarities of these processes is discussed in more detail. It is also shown that the otherwise ‘non-polymerizable’ BL does form high molecular weight copolymers with CL, containing up to 50 mol% repeating units derived from BL. Their molecular weight is controlled by the concentrations of the consumed comonomers and the starting concentration of the initiator. NMR and DSC data indicate the random structure of copolymers. TGA traces of the BL/CL copolymers show that the presence of the γ-oxybutyryl repeating units randomly distributed within the poly(CL) chains improves the thermal stability of the latter.

On the mechanism of polymerization of cyclic esters induced by tin(II) octoate

Mechanism of initiation and propagation in polymerization of ϵ-caprolactone and L,L-dilactide induced with tin(II) octoate (Sn(Oct)2) and Sn(Oct)2/n-butyl alcohol system is presented. Tin(II) alkoxide bond formation is required in reaction of Sn(Oct)2 with hydroxyl group containing compound to form a true initiator. Then tin(II) alkoxide end group is an active centre in the further propagation.

Living polymerization with reversible chain transfer and reversible deactivation: The case of cyclic esters

Polymerization of cyclic esters at the properly chosen conditions can be treated as living polymerization, in agreement with the tentative definition of the Nomenclature Commission of IUPAC (Macromolecular Division) requiring that no irreversible transfer or irreversible termination take place. For these processes the most kinetic or structural (end group) studies do not reveal any deviation. However, since in these polymerizations reversible transfer to backbones of macromolecules and/or reversible deactivation take place, the molar mass distribution can be Poissonian only at certain conditions. These processes have been studied quantitatively and the corresponding rate constants were determined. Thus, the importance of these processes could be established by comparing the rate constants of transfer and/or deactivation with rate constants of propagation. In this way, polymerizations of cyclic esters were used to illustrate the meaning and scope of the definition of “living polymerization”, a process from which irreversible transfer and deactivation are absent and in which living polymers are formed, i. e. composed of macromolecules that do not irreversibly loose their ability to grow.

Solid-state NMR spectroscopy as a tool supporting optimization of MALDI-TOF MS analysis of polylactides

We report systematic structural studies of poly(l-lactide) (PLLA) employing matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) and solid-state NMR spectroscopy. 13C cross polarization magic angle spinning (CP/MAS) NMR data for 1,8-dihydroxy-9-anthracenone (DT), 2,5-dihydroxybenzoic acid (DHB), 2-(4-hydroxyphenylazo)-benzoic acid (HABA), and trans-3-indoleacrylic acid (IAA), four matrices commonly used in MALDI-TOF analysis of polymers, were analyzed to test the influence of crystallization conditions (solvent, inorganic salt) on sample morphology. 13C principal elements of chemical shift tensor (CST) and line-shape analyses were employed to study of the nature of hydrogen bonding and to evaluate the crystallinity and amorphicity of the pure polymer. NMR parameters for PLLA were compared with data for polylactide crystallized with the four matrices under different conditions with the addition of two inorganic salts as cationization agents. This study revealed that the semicrystalline structure of the polymer does not change when it is embedded in the matrix.

Water soluble well-defined acidic graft copolymers based on a poly(propylene glycol) macromonomer

A series of well-defined amphiphilic graft copolymers based on poly(propylene glycol)methacrylate (PPGMA) extended with a polymethacrylate segment containing methacrylic acid units was successfully synthesized, combining atom transfer radical polymerization (ATRP), esterification, “grafting from” polymerization, and acidolysis. The multistep procedure yielded hydroxy-functionalized polymers (6–47 mol% of PPGMA), bromoester-functionalized copolymers as multifunctional macroinitiators (nBr = 8–25), PPGMA-based copolymers with poly(tert-butyl methacrylate) (PtBMA) segments (DPtBMA = 18–59), and copolymers varying in hydrophilic fraction content (FMAA = 0.28–0.54). After the generation of methacrylic acid units the PPGMA-based graft polymers attained a good solubility in polar solvents such as methanol and water. The particles, which were formed in aqueous solution, achieved sizes in the nanoscale range (165–230 nm) and negative zeta potentials.

Molecular and Supramolecular Changes in Polybutylene Succinate (PBS) and Polybutylene Succinate Adipate (PBSA) Copolymer during Degradation in Various Environmental Conditions

In this paper, the influence of the various degradation conditions, on the molecular and supramolecular structure of polybutylene succinate (PBS) and polybutylene succinate adipate (PBSA) copolymer during degradation is described. The experiment was carried out by the use of injection molded samples and normalized conditions of biodegradation in soil, composting and artificial weathering. Materials were studied by size-exclusion chromatography (SEC) coupled with multiangle laser light scattering (MALLS) detection and wide-angle X-ray diffraction (WAXD). Additionally, the physical and mechanical properties of the samples were determined. The performed experiments clearly show difference impacts of the selected degradation conditions on the macroscopic, supramolecular and molecular parameters of the studied aliphatic polyesters. The structural changes in PBS and PBSA explain the observed changes in the physical and mechanical properties of the obtained injection molded samples.

Influence of the homehold composting conditions on the structural changes of polylactide spun-bonded nonwovens during degradation

In this study, the influence of homehold composting conditions on the molecular and supramolecular structure of polylactide (PLA) in the form of spun-bonded nonwovens was investigated. Nonwoven samples were studied using size-exclusion chromatography coupled with multiangle laser light scattering detection, wide-angle X-ray diffraction, differential scanning calorimetry and Fourier transform infrared spectroscopy. In addition, the physical and mechanical properties of the nonwovens before and after composting were determined. The results show the varying degree of influence of the prepared compost mixtures of soil with common horticultural additives, such as chalk, commercially available agents, cow manure and chicken litter, on the molecular and supramolecular structure of PLA and its degradation rate. The obtained experiment explained which popular homehold agent had the strongest affect on the PLA nonwoven dedicated for agriculture use in the first period of season composting (first 6 months).