Regarding the dynamic development of 3D printing technology, as well as its application in a growing part of industries, i.e., in the automotive industry, construction industry, medical industry, etc., there is a notable opportunity for its application in producing dental implants, which presents a promising alternative to traditional implant manufacturing methods. The medical industry is very restrictive regarding the applied materials, and it is necessary to use materials that exhibit very good mechanical and thermal parameters, show clinical indifference and biocompatibility, are non-allergenic and non-cancerous, and are likely to sterilize. Such materials are poly(aryl-ether-ketone)s (PAEK)s, mainly poly(ether-ether-ketone) (PEEK) and poly(ether-ketone-ketone) (PEKK), that are found to be high-performance polymers and can be defined as materials that retain their functionality even in extreme conditions. In the present paper, two types of PEEKs and PEKK were compared regarding their structural, mechanical, and thermal properties along with the biological activity toward selected strains. The tested samples were obtained with Fused Deposition Modeling (FDM) technology. The PEKK, after heat treatment, exhibits the most promising mechanical properties as well as less bacterial adhesion on its surface when compared to both PEEKs. Consequently, among the evaluated materials, PEKK after heat treatment stands out as the optimal selection for a dental prosthesis.

Recently, photocurable coatings are being used frequently. However, it is worth mentioning that the use of photopolymerization has its drawbacks, especially in the case of curing coatings on three-dimensional surfaces and in places that are difficult to access for UV radiation. However, it is possible to develop a system in which UV technology and thermal methods for curing coatings can be combined. Moreover, the obtained resins are derived from low-viscosity epoxy resins or diglycidyl ethers, making them an ideal building material for photopolymerization-based three-dimensional printing techniques. Due to the need to improve this method, a series of epoxy (meth)acrylates containing both epoxy and (meth)acrylate groups were obtained via the addition of acrylic or methacrylic acid to epoxy resin, diglycydylether of bisphenol A epoxy resin (DGEBA), cyclohexane dimethanol diglycidyl ether (CHDMDE) and neopentyl glycol diglycidyl ether (NPDE). The structures of the synthesized copolymers were confirmed through spectroscopic analysis (FTIR) and studied regarding their nonvolatile matter content (NV) and acid values (PAVs), as well as their epoxy equivalent values (EEs). Due to the presence of both epoxy and double carbon–carbon pendant groups, two distinct mechanisms can be applied: cationic and radical. Hence, the obtained resins can be cured using UV radiation with thermally appropriate conditions and initiators. This type of method can be used as a solution to many problems currently encountered in using UV technology, such as failure to cure coatings in underexposed areas as well as deformation of coatings. Synthesized epoxy (meth)acrylate prepolymers were employed to formulate photocurable coating compositions. Furthermore, the curing process and properties of cured coatings were investigated regarding some structural factors and parameters. Among the synthesized materials, the most promising are those based on epoxy resin, characterized by their high glass transition temperature values and satisfactory functional properties.

In recent years, there has been a trend toward replacing petrochemical raw materials with so-called “bio” plastics, i.e. plastics from renewable sources. Herein, the susceptibility of degradation in the compost heap of three types of packaging polyesters, by means of PET and biobased PEF and PLA, with other thermoplastic polyesters with more methylene groups (three and six) bio—(PTF and PHF, respectively) and petrochemically-based (PTT and PHT, respectively) has been studied. Two series of polymer materials based on ethylene, propylene, and hexamethylene glycols and two diesters (dimethyl terephthalate and dimethyl 2,5-furandicarboxylate) were thus obtained and compared with “double green” PLA. Moreover, the assessment of the influence of the subsequent processing cycle (injection moulding) on the utilitarian properties of these materials, constitutes the analogy to the subsequent recycling cycle. The susceptibility to degradation was assessed in the context of changes in the structure (analyzed by FTIR and DSC), intrinsic viscosity, and mechanical performance. In addition, chromatographic analysis of the solutions of the analyzed samples in methanol was carried out in order to determine whether and what low-molecular compounds were released from the analyzed polyesters. It has been shown that furan-based polyesters have great potential to replace materials based on dimethyl terephthalate-based polyesters.

The growing ecological awareness of society created the tendency to replace petrochemically based materials with alternative energy carriers and renewable raw materials. One of the most requested groups of polymer materials with significant technological importance is thermoplastic elastomers (TPE). They combine the properties of elastomers such as flexibility with the typical properties of thermoplastics, like easy processing. Herein, one compares the influence of rigid segments on the properties of copoly(ester-ether). Thermoplastic polyesters based on bio-1,6-hexanediol and terephthalic (T), furanic (F), and napthalate (N) diesters, i.e., PHT, PHF, and PHN, were obtained employing melt polycondensation. Additionally, to grant elastic properties of polyesters, systems containing 50 wt.% of bio-based polyTHF^®1000 (pTHF) with a molecular mass of 1000 g/mol, have been prepared. The composition and chemical structure have been determined by ¹H nuclear magnetic resonance (NMR) and Fourier transformed infrared spectroscopy (FTIR) analyses. The temperatures corresponding to phase transition changes were characterized by differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMTA) analyses. The crystalline structure was examined by X-ray diffraction (XRD) analysis. Additionally, the influence of pTHF–rich segment on the tensile properties, water absorption, as well as thermal and thermo-oxidative stability, has been analyzed. It was found that incorporation of soft phase allows creation of thermoplastic elastomers with tensile characteristics comparable to the commercially available ones, by means of elongation at break higher than 500%, low values of tensile modulus, without exhibiting yield point.

Two series based on poly(propylene 2,5-furandicarboxylate)-block-poly(tetramethylene oxide) (PPF-b-F-PTMO) containing carbon and mineral nanofillers that differ in shape (1D and 2D) were synthesized via in situ polymerization. The influence of the addition of the 1D-type nanoparticle, i.e., carbon nanofibers (CNFs) and halloysite nanotubes (HNTs), and the so-called 2D-type, i.e., graphene nanoplatelets (GNPs) and organoclay (C20A), on the properties of a biobased block copolymer was analyzed. The dispersion of nanoadditives in the nanocomposites was determined using a scanning electron microscope (SEM). The thermal properties were studied employing differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The introduction of nanoparticles increased the crystallinity (X_c) and the mean values of tensile modulus (E) of the bionanocomposites. In turn, one observed that the decrease in the limited viscosity number (LVN) was visible along with incorporating nanoadditives. The synthesized polymer bionanocomposites reveal the mechanical properties of elastomers during mechanical testing. Moreover, the good processability of the obtained materials by injection molding combined with the comprehensive ability to change mechanical and thermal properties of PPF-b-F-PTMO by tailoring the type and content of the nanofillers can indicate their possible applications in packaging, automotive, sports, construction, and many other industries.

The replacement of polymers derived from petrochemical resources has been a prominent area of focus in recent decades. Polymers used in engineering materials must exhibit mechanical strength and stiffness while maintaining performance through a broad temperature range. Most of the polyesters used as engineering materials are based on terephthalic acid (TPA) and its derivatives, which provide necessary rigidity to molecular chains due to an aromatic ring. Bio-based alternatives for TPA-based polyesters that are gaining popularity are the polyesters derived from 2,5-furandicarboxylic acid (FDCA). To broaden applicational possibilities, one effective way to achieve specific properties in targeted applications is to adjust the composition and structure of polymers using advanced polymer chemistry techniques. The incorporation of rigid diols such as isosorbide, 1,4-cyclohexanedimethanol (CHDM), and 2,2,4,4-tetramethyl-1,3-cyclobutanediol (CBDO) should result in a greater stiffness of the molecular chains. This review extensively explores the effect of incorporating rigid diols on material properties through a review of research articles as well as patents. Moreover, this review mainly focuses on the polyesters and copolyesters synthesized via two-step melt polycondensation and its alterations due to the industrial importance of this method. Innovative synthesis strategies and the resulting material properties are presented.