Pavel Kucharczyk

Correlation of Morphology and Viscoelastic Properties of Partially Biodegradable Polymer Blends Based on Polyamide 6 and Polylactide Copolyester

The morphology and viscoelastic properties of newly prepared partially biodegradable polymeric blend based on polyamide 6 and commercially available co-polyester of polylactide, BioFlex®, were studied in this work. Observations by scanning electron microscopy and solvent extraction method, and rheological measurements were carried out for structural studies. Experimental data were compared with several semi-empirical models for determination of phase inversion concentration. The correlation between experimental data and models reveals the significant contribution of elasticity effect to interfacial adhesion between polyamide 6 and BioFlex, which seems to have influence on the phase inversion composition of the blends and co-continuous morphology formation.

Low molecular weight poly(lactic acid) microparticles for controlled release of the herbicide metazachlor: preparation, morphology, and release kinetics.

The preemergence chloroacetamide herbicide metazachlor was encapsulated in biodegradable low molecular weight poly(lactic acid) micro- and submicroparticles, and its release to the water environment was investigated. Three series of particles, S, M, and L, varying in their size (from 0.6 to 8 μm) and with various initial amounts of the active agent (5%, 10%, 20%, 30% w/w) were prepared by the oil-in-water solvent evaporation technique with gelatin as biodegradable surfactant. The encapsulation efficiencies reached were about 60% and appeared to be lower for smaller particles. Generally, it was found that the rate of herbicide release decreased with increasing size of particles. After 30 days the portions of the herbicide released for its highest loading (30% w/w) were 92%, 56%, and 34% for about 0.6, 0.8, and 8 μm particles, respectively. The release rates were also lower for lower herbicide loadings. Metazachlor release from larger particles tended to be a diffusion-controlled process, while for smaller particles the kinetics was strongly influenced by an initial burst release.

Properties enhancement of partially biodegradable polyamide/polylactide blends through compatibilization with novel polyalkenyl-poly-maleic-anhydride-amide/imide-based additives

This work is dedicated to compatibilization process investigation between polyamide 6 and biodegradable polylactide. The process was conducted by newly developed polyalkenyl-poly-maleic-anhydride-imide/amide agents over a selected range of composition to identify morphologies and properties of these blends. The properties of resulted blends were studied by scanning electron microscopy, solvent extraction techniques, mechanical testing, Fourier transform infrared spectroscopy, and differential scanning calorimetry measurements. Results show that blending of the two polymers without compatibilizers produced multiphase blends. It was shown by scanning electron microscopy imaging that addition of prepared compatibilizers reduced a domain size of a dispersed phase and also changes in nearly co-continuous state occurred. Static and dynamic mechanical properties were improved, and especially impact strength and tensile strength were the most sensitive on the presence of compatibilizers.

Chitosan grafted low molecular weight polylactic acid for protein encapsulation and burst effect reduction

Chitosan and chitosan-grafted polylactic acid as a matrix for BSA encapsulation in a nanoparticle structure were prepared through a polyelectrolyte complexation method with dextran sulfate. Polylactic acid was synthetized via a polycondensation reaction using the non-metal-based initiator methanesulfonic acid and grafted to the chitosan backbone by a coupling reaction, with 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide as the condensing agent. The effect of concentration of the polymer matrix utilized herein on particle diameter, ζ-potential, encapsulation efficiency, and the release kinetic of the model protein bovine serum albumin at differing pH levels was investigated. The influence of pH and ionic strength on the behavior of the nanoparticles prepared was also researched. Results showed that grafting polylactic acid to chitosan chains reduced the initial burst effect in the kinetics of BSA release from the structure of the nanoparticles. Furthermore, a rise in encapsulation efficiency of the bovine serum albumin and diminishment in nanoparticle diameter were observed due to chitosan modification. The results suggest that both polymers actually show appreciable encapsulation efficiency; and release rate of BSA. CS-g-PLA is more suitable than unmodified CS as a carrier for controlled protein delivery.

Characterization of polyhydroxyalkanoates produced by Synechocystis salina from digestate supernatant

The current commercial production of polyhydroxyalkanoates (PHA) is based on heterotrophic bacteria, using organic carbon sources from crops. To avoid the competition with food and feed production, cyanobacteria, metabolising PHA from carbon dioxide can be used. This research focuses on the investigation of the thermal and rheological properties of PHA polymers accumulated by Synechocystis salina, which had been cultivated in digestate supernatant and a mineral medium. The dried bacterial cells had a polymer content of 5.5-6.6%. The relevance of the derived PHA polymers for the common melt polymer processing was correlated with their molecular mass distribution as well as with their thermal and rheological properties. The determined thermal and rheological properties showed that PHA polymers accumulated by S. salina on digestate supernatant or mineral medium are comparable with the commercial available poly(3-hydroxybutyrate). However, the results showed that PHA polymers in general require modification before melt processing to increase their stability in the molten state.

The Effect of Various Catalytic Systems on Solid-State Polymerization of Poly-(L-lactic acid)

There are several methods for synthesizing polylactic acid. Solid-state polymerization is one of the most promising methods due to the great feasibility and beneficial properties of the final polymer. In terms of this study, the purpose was to evaluate the effect of various catalyst systems (based on tin dichloride, tin dioxide, tin octoate, citric acid, sulphuric acid, toluenesulfonic acid and methane sulfonic acid) and focus on the molecular weight, structure and thermal properties of the final products. The molecular weight was shown to be controlled by different catalytic systems and Mw > 100,000 g/mol was achieved after 24 h of synthesis, which is more than in the conventional melt polycondensation process. Thermal stability was found to be negatively affected by the catalytic system, although relatively positive results can still be achieved.

Chitosan-based nanocomplexes for simultaneous loading, burst reduction and controlled release of doxorubicin and 5-fluorouracil

In this work, nanocomplexes based on chitosan grafted by carboxy-modified polylactic acid (SPLA) were prepared with the aim of loading simultaneously two anticancer drugs - doxorubicin and 5-fluorouracil, as well as to control their release, reduce the initial burst and boost cytotoxicity. The SPLA was prepared by a polycondensation reaction, using pentetic acid as the core molecule, and linked to the chitosan backbone through a coupling reaction. Nanocomplexes loaded with both drugs were formulated by the polyelectrolyte complexation method. The structure of the SPLA was characterized by 1H NMR, while the product CS-SPLA was analyzed by FTIR-ATR to prove the occurrence of the reaction. Results showed that the diameters and ζ-potential of the nanocomplexes fall in the range 120-200nm and 20-37mV, respectively. SEM and TEM analysis confirmed the spherical shape and dimensions of the nanocomplexes. The presence of hydrophobic side chain SPLA did not influence the encapsulation efficiency of the drugs but strongly reduced the initial burst and prolonged release over time compared to unmodified chitosan. MS analysis showed that no degradation or interactions between the drugs and carrier were exhibited after loading or 24h of release had taken place, confirming the protective role of the nanocomplexes. In vitro tests demonstrated an increase in the cytotoxicity of the drugs when loaded in the prepared carriers.

Production of Acrylonitrile Butadiene Styrene/High-Density Polyethylene Composites from Waste Sources by Using Coupling Agents

A possible way of recycling plastic wastes has been investigated. Polyalkenyl-poly-maleic-anhydride derivates were synthesized and employed in ABS and HDPE blends to eliminate their immiscibility. By this way, the recycling of ABS and HDPE could be performed with improved mechanical properties of reshaped specimens.

The Effect of Plasma Treatment on the Release Kinetics of a Chemotherapy Drug from Biodegradable Polyester Films and Polyester-Urethane Films

ABSTRACT Investigation was made into the effect of plasma treatment on the release kinetics of the drug Temozolomide (TMZ) from thin, biodegradable polyester films, comprising polylactic acid (PLA) and polyester urethane. The authors utilized two systems to achieve this, the first being diffuse coplanar surface barrier discharge, applying air as the gaseous medium, while the other involved capacitively coupled radio frequency discharge plasma under an argon atmosphere with hexamethyldisiloxane. Results showed that both forms of plasma treatment positively reduced the undesirable burst effect and benefited the release rate of TMZ. The hydrolytic degradability of the materials was slightly enhanced following hydrophilization, whereas the same diminished after hydrophobization had taken place. This was especially true for PLA due to modification of its wettability. GRAPHICAL ABSTRACT

Synthesis and characterization of star-shaped carboxyl group functionalized poly(lactic acid) through polycondensation reaction

Present paper deals with the preparation and characterization of carboxyl-functionalized poly(lactic acid) (PLA) of non-linear, star-shaped architecture prepared by direct melt polycondensation of lactic acid and pentetic acid - applied as a star polymer core. Influence of the optical purity of the lactic acid (L or DL) on the structure and properties of the product is investigated in close details. The influence of pentetic acid core on molar mass, as analysed by the means of gel permeation chromatography using triple detection (refractive index, light scattering and viscometric detectors) is performed as a detailed survey. Furthermore FTIR and NMR spectra, end group analysis, and water contact angle measurements were analysed to receive detailed product characteristics. Differential scanning calorimetry was carried out to examine thermal properties. Obtained results confirm the possibility of the starshaped structure preparation using a simple polycondensation reaction. The properties of the prepared polymers were found to be dependent on optical purity of the lactic acid precursor.