Nowadays, unsaturated polyester resins (UPR) are mainly obtained from non-renewable resources. The ever-increasing regulations and the continuous demand for more sustainability have led to extensive research towards more environmentally suitable alternatives to petroleum-based materials. However, one of the main disadvantages of bio-based UPR is their relatively high viscosity compared to petrochemical ones. In order to overcome this drawback, in this work, we investigated the possibility to lower the resin viscosity utilizing a mixture of dimethyl itaconate (DMI) and methyl methacrylate (MMA) as a reactive diluent. The effect of the DMI and MMA ratio on resin rheological properties was investigated. The optimal curing parameters were determined and all UPRs had a high gel content, which was shown to be dependent on the DMI and MMA ratio in the formulation. Furthermore, thermomechanical and mechanical properties of the resulting network were also found to be affected by the used reactive diluent mixture. A small substitution of DMI by MMA proved to be advantageous since it offers lower resin viscosity and improved mechanical properties.

The scope of the present study was to prepare fully bio-based unsaturated polyester resins (UPRs) with comparable properties to the commercial formulations. The focus was set on the determination of the optimal prepolymer formulation using the same set of diacids (itaconic and succinic acid) and different diols (propylene glycol, isosorbide and neopentyl glycol) or its equimolar mixtures, keeping the fixed molar ratio of 1:1:2.1 in all feed compositions. Instead of commonly used styrene, bio-based dimethyl itaconate was used as a reactive diluent (RD). The rheology of the obtained resins was studied in detail. The effect of the used diol on structural (FTIR), thermal (DSC), thermomechanical (DMA), and mechanical (tensile) properties was explained. The properties of UPRs were found to be highly dependent on the diol used in the prepolymer formulation. The UPR with an equimolar ratio of propylene glycol and neopentyl glycol was shown to be the most promising candidate to compete with the commercial petroleum-based resins.

Drug delivery system is an amazing tool which is widely used for drug protection and its controlled release in order to enhance drug bioavailability, reduce side effects and therefore to improve overall therapy. Hydrogels have been attracted great attention as drug carriers due to their great physicochemical properties, similarity to the living tissues and biocompatibility. One group of pH sensitive hydrogels are based on poly(methacrylic acid) (PMAA). These non-toxic hydrogels are used as drug delivery system because they swell as a response to the change in pH of external environment and drug is being released during the process. In present study, in order to improve the control of drug release rate, caffeine was encapsulated in liposomes which were further embedded into PMC hydrogel (PMCL). It was investigated how the change in neutralization degree of methacrylic acid affect the swelling degree of PMCL hydrogels and caffeine release in two environments at 37 °C for 24 h: 0.1 M hydrochloride acid (pH 1) and phosphate buffer with pH value of 6.8 (pH 6.8), as a simulation of pH environment in human stomach and intestines, respectively. Obtained results show that PMCL hydrogels have great potential for controlled release of poorly water-soluble drugs in human intestines.