Description for the general public – when the project was submitted
The aim of the project is to obtain polymeric nonwoven using electrospinning method and to characterize its properties. Material will consist of two components. One will be poly(glycerol sebacate), PGS – polyester with elastomeric-like properties, with good elasticity. The second component of nonwovens will be the other biodegradable polymer, from polyesters group. Electrospun materials consisting of popular, biodegradable polyesters usually lack hydrophilicity and elasticity. Addition of PGS to the polymeric system is likely to modify properties of polylactide (PLA) or its copolymer PLGA in a way to make them more appropriate for application within the scope of soft tissues engineering e.g. connective tissue or some muscles. Soft tissues are largely composed of collagen and elastin fibers. Mechanical properties of PGS are similar to native fibrous structures in soft tissues, but reproducibility of PGS using electrospinning method is very complicated. The use of PGS as an additive in bicomponent polymeric system partially bypasses typical problems and it modifies, in a potentially positive way, properties of the so-called carrier material – the second component. To achieve it and to estimate the real potential of such material, elementary research studies are indispensable.
Popularizing description of the project results – when the project was finished
As a result of the project, in cooperation with the Faculty of Chemistry of the Warsaw University of Technology, the process of synthesizing two poly(glycerol sebacate) (PGS) prepolymers was successfully developed. The processing of these prepolymers by electrospinning using their mixtures with polylactide (PLLA) was successfully carried out. The main difference between obtained prepolymers was the crosslinking ability under the same time-temperature-vacuum conditions. Both obtained prepolymers were spinnable in a wide range of compositions (PGS: PLLA ratio) and provided a diversified influence on the properties of nonwovens obtained with their addition. The prepolymer less susceptible to cross-linking, with a lower viscosity, provided PLLA-based nonwovens very good hydrophilicity, while the prepolymer more susceptible to cross-linking provided a much more time-effective process of reaching the cross-linked material to the crosslinking level of at least 80% and had a smaller effect on changes in the morphology of fibers after the crosslinking process.
The addition of both PGS prepolymers changed the mechanical properties of the nonwovens - reduced their stiffness and increased their deformability at low stress values (compared to nonwovens made of PLLA only), but no benefit was observed in the form of an increase in the level of reversible deformations, i.e. increased elasticity. The obtained prepolymers, in a single-component, cross-linked form, had elastomeric properties, but in two-component nonwovens, polylactide seemed to impose the characteristics of the course of mechanical tests, even when PGS accounted for 50% or more weight contribution in the composition.
The project in itself contributed to the development and better knowledge of the subject matter not only at IPPT PAN but also at the Faculty of Chemistry of the Warsaw University of Technology, which intensified the work and thanks to the commitment of many people, it became the starting point for the implementation of diploma theses or conducting independent research in the disciplines of materials engineering and polymer chemistry. Even though PGS and PLLA are very well known polymers the research subject carried out in the project is not very popular. The processing of PGS and PLLA in the form of mixtures by electrospinning method is a research niche to which the project contributed.
The project was carried out with good results and additionally contributed to the development of the topic of the synthesis of an alternative material, very close to PGS, poly(glycerol citrate), PGCit, which also has elastomeric properties and is biodegradable. The results of the project were presented in the form of posters at three conferences - in 2018 in Hungary (BiPoCo 2018) and Poland (PICETE 2018), and in 2019 in Greece (Termis 2019). So far, there has been one publication presenting the results of the project, which appeared in the Polymers journal (MDPI) in the open-access system at the end of 2019. The second publication, concerning additionally achieved goals, has been submitted and is waiting for a decision.
