High pressure as a novel tool for the cationic ROP of γ-butyrolactone

In this study, we report the acid-catalyzed and high pressure assisted ring-opening polymerization (ROP) of g-butyrolactone (GBL). The use of a dually-catalyzed approach combining an external physical factor and internal catalyst (trifluoromethanesulfonic acid (TfOH) or p-toluenesulfonic acid (PTSA)) enforced ROP of GBL, which is considered as hardly polymerizable monomer still remaining a challenge for the modern polymer chemistry. The experiments performed at various thermodynamic conditions (T ¼ 278–323 K and p ¼ 700–1500 MPa) clearly showed that the high pressure supported polymerization process led to obtaining well-defined macromolecules of better parameters (Mn ¼ 2200–9700 g mol 1; Đ ¼ 1.05–1.46) than those previously reported. Furthermore, the parabolic-like dependence of both the molecular weight (MW) and the yield of obtained polymers on variation in temperature and pressure at either isobaric or isothermal conditions was also noticed, allowing the determination of optimal conditions for the polymerization process. However, most importantly, this strategy allowed to significantly reduce the reaction time (just 3 h at room temperature) and increase the yield of obtained polymers (up to 0.62 gPGBL/gGBL). Moreover, despite using a strongly acidic catalyst, synthesized polymers remained non-toxic and biocompatible, as proven by the cytotoxicity test we performed in further analysis. Additional investigation (including MALDI-TOF measurements) showed that the catalyst selection affected not only MW and yield but also the linear/cyclic form content in obtained macromolecules. These findings show the way to tune the properties of PGBL and obtain polymer suitable for application in the biomedical industry

The effect of high-pressure on organocatalyzed ROP of γ-butyrolactone

In this paper, we report 1,5,7-Triazabicyclo[4.4.0]dec-5-ene (TBD) supported high-pressure approach enforcing Ring-Opening Polymerization (ROP) of γ-butyrolactone (GBL), that due to unfavorable thermodynamics and low ring strain, is considered as a hardly polymerizable monomer. Application of Broadband Dielectric Spectroscopy (BDS) allowed us to find optimal thermodynamic conditions to perform well-controlled and notably fast polymerization (even within 1 h!), avoiding undesired crystallization process. It was shown that by varying pressure and temperature conditions, we could control molecular weight, dispersity of recovered macromolecules, as well as rate and efficiency of the reaction that are significantly altered with respect to the reference process carried out at ambient conditions. Experiments performed at respectively very low temperature T = 233 K and low/ moderate pressure (p = 75–250 MPa) and much higher temperatures (T = 248–268 K) and compressions (p = 1000 MPa) yielded poly(γ-butyrolactone) (PGBL) of tailored absolute molecular weight in moderate range Mn = 2.8–15.0 (up to 30.3) kg/mol and narrow/moderate dispersity ranging from Đ = 1.12–1.89. What is more, the implementation of MALDI-TOF, GPC and DSC analyses, clearly indicated that as i) the time of reaction gets longer, ii) the amount of catalyst increases, iii) the temperature lowers, the content of cyclic products in produced polymers grows. This phenomenon influences the rheological properties (viscosity), foil formation ability (films) and cell culture proliferation features of the recovered macromolecules. Presented results open a highly effective and repeatable route to produce PGBL via pressure-assisted ROP and indicate the possibility of tuning properties of this polymer by varying concentration of cycles or eventual block copolymerization with other biorelevant monomers to meet the expectations of the biotechnological industry

Block and random copolymers of ε-caprolactone

Conditions of the living homopolymerization of epsilon-caprolactone (CL), lactides (LA), and of the homo-oligomerization of gamma-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 gamma-oxybutyryl repeating units randomly distributed within the poly(CL) chains improves the thermal stability of the latter

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

The comparison of Mexican genotypes and Polish varieties of spring wheat regarding the major yielding traits

Ważnym czynnikiem ograniczającym plonowanie pszenicy jarej jest susza. Stąd potrzeba większego nacisku w pracach hodowlanych na selekcję odmian dostosowanych do warunków z występującymi niedoborami wilgoci. W latach 2013–2015 przeprowadzono cykl doświadczeń polowych dla wybranych genotypów pszenicy jarej pochodzących ze szkółki CIMMYT (o podwyższonej tolerancji na stres suszy) oraz odmian z rejestru PL (odmiany zarejestrowane w Polsce): Harendra, Hewilla, Izera, Ostka Smolicka, Torridon, Trappe i Tybalt. Na podstawie uzyskanych wyników z doświadczeń wyliczono średnie dla lat oraz współczynniki korelacji fenotypowej pomiędzy plonem pszenicy jarej a cechami użytkowymi. Otrzymano ujemną korelację plonu z terminem kłoszenia. Ujemne związki z plonem stwierdzono również dla zawartości białka, glutenu oraz liczby sedymentacji. Uzyskane plony, średnie z 2-lecia mieściły się w zakresie od 69,7 dt/ha do 107,3 dt/ha. Kilka linii z CIMMYT plonowało na poziomie odmian krajowych. Linie pochodzące z CIMMYT charakteryzowały się wyższą masą 1000 nasion, korzystniejszymi parametrami wstępnej oceny technologicznej oraz lepszą odpornością na choroby grzybowe.Drought is an important limiting factor for crop yield improvement. Therefore, there is a need for more emphasis on selection of breeding material suited for conditions with frequent water deficits. In 2013–2015 field experiments were conducted for selected spring wheat genotypes from CIMMYT (with increased tolerance to drought stress) and varieties from the Polish register: Harendra, Hewilla, Izera, Ostka Smolicka, Torridon, Trappe and Tybalt. Based on the results obtained from the experiments, the mean yield of the years and the phenotypic correlation coefficients between the yield and the functional characteristics were calculated. Negative correlation of yield with heading time was observed. Also negative correlations with yields were found for protein and gluten content and sedimentation. The 2-year average for the yield ranged from 69.7 dt / ha to 107.3 dt / ha. Several lines from CIMMYT yielded at the level of domestic varieties. The CIMMYT lines were characterized by a higher weight of 1000 grains, more favorable initial technological evaluation and a better resistance to fungal diseases