Polylactic acid (PLA) is the most widely used raw material in extrusion-based three-dimensional (3D) printing (fused deposition modeling, FDM approach) in many areas since it is biodegradable and environmentally friendly, however its utilization is limited due to some of its disadvantages such as mechanical weakness, water solubility rate, etc. FDM is a simple and more cost-effective fabrication process compared to other 3D printing techniques. Unfortunately, there are deficiencies of the FDM approach, such as mechanical weakness of the FDM parts compared to the parts produced by the conventional injection and compression molding methods. Preparation of PLA composites with suitable additives is the most useful technique to improve the properties of the 3D-printed PLA parts obtained by the FDM method. In the last decade, newly developed PLA composites find large usage areas both in academic and industrial circles. This review focuses on the chemistry and properties of pure PLA and also the preparation methods of the PLA composites which will be used as a raw material in 3D printers. The main drawbacks of the pure PLA filaments and the necessity for the preparation of PLA composites which will be employed in the FDM-based 3D printing applications is also discussed in the first part. The current methods to obtain PLA composites as raw materials to be used as filaments in the extrusion-based 3D printing are given in the second part. The applications of the novel PLA composites by utilizing the FDM-based 3D printing technology in the fields of biomedical, tissue engineering, human bone repair, antibacterial, bioprinting, electrical conductivity, electromagnetic, sensor, battery, automotive, aviation, four-dimensional (4D) printing, smart textile, environmental, and luminescence applications are presented and critically discussed in the third part of this review.

Our study is concerned with the development of a novel type of layer-by-layer (LbL) self-assembled membrane from a single cationic polyelectrolyte (PE) and blended anionic PEs. Their synthetic seawater stability is investigated as a function of PE type and blend ratios using quartz crystal microbalance-dissipation (QCM-D). These materials adsorbed into multilayers with significant viscoelasticity. Poly(allylamine hydrochloride) (PAH) and poly(vinylamine hydrochloride) (PVA) based LbL blend films did not show any multilayer decomposition with the addition of synthetic seawater regardless of blend ratio while chitosan based multilayers disintegrated. The flux of PVA based blend membrane to water with 1,000 ppm NaCl was found to be 6.7 L/ m 2 .h at 40 bar and the flux properties of the membranes were highly dependent on both the thickness and hydrophilicity of multilayers. Ion rejection can be controlled with the charge of the top layer consistent with a Donnan exclusion approach. Sodium ion rejection of 60.5 layered LbL blend membrane was 98.4% at 40 bar and it was determined that sodium ion rejection improved 110.7% compared to a commercial nanofiltration membrane. POLYM. ENG. SCI., 60:1006-1018, 2020

Superhydrophobic (SH) polylactic acid (PLA) surfaces were previously produced by various methods and used especially in biomedical applications and oil/water separation processes after 2008. However, the wettability of SH-PLA patterns containing micropillars has not been investigated before. In this study, PLA patterns having regular microstructured pillars with 12 different pillar diameters and pillar-to-pillar distances were prepared by hot pressing pre-flattened PLA sheets onto preformed polydimethylsiloxane (PDMS) soft molds having micro-sized pits. PDMS templates were previously prepared by photolithography using SU-8 molds. Apparent, advancing, and receding water contact angle measurements were carried out on the PLA patterns containing micropillars, and the morphology of the patterns was examined by optical and SEM microscopy. The largest contact angle obtained without the surface modification of the pure PLA pattern was 139°. Then, PLA micropatterns were hydrophobized using three types of silanes via chemical vapor deposition method, and SH-PLA patterns were obtained having θs of up to 167°. It was found that the highest θ values could be obtained when PLA pattern samples were coated with a silane containing a fluorine atom in its chemical structure. Washing and service life stability tests were also performed on the coated pattern samples and all of the silane coatings on the PLA patterns were found to be resistant over a 6 month period.