4D Printing‐Encapsulated Polycaprolactone–Thermoplastic Polyurethane with High Shape Memory Performances

Abstract

There are a few shape memory polymers (SMPs) like polylactic acid (PLA) and polyurethane (PU) that are 4D printable, and other SMPs must be synthesized with a complicated chemical lab effort. Herein, considering dual‐material extrusion printing and microscopic mechanism behind shape memory effect (SME), bilayer‐encapsulated polycaprolactone (PCL)–thermoplastic polyurethane (TPU) shape memory composite structures are 4D printed for the first time. The SME performance is investigated by assessing fixity, shape recovery, stress recovery, and stress relaxation under bending and compression loading modes. PCL, TPU, and melting temperature of PCL play the role of switching phase, net point, and transition temperature, respectively. Due to the destruction and dripping of molten PCL in contact with water, PCL is encapsulated by TPU. Encapsulation successfully solves the challenge of bonding/interface between printed layers, and the results show that the SME performance of the encapsulated structures is higher than bilayer PCL–TPU one's. Experiments reveal that maximum stress recovery in 4D‐printed composites remains constant over time. This is a great achievement compared to the previous extrusion‐based SMP structures that have great weakness in stress relaxation due to weak and low crystalline fractions and the unraveling of molecular entanglements in semicrystalline and amorphous thermoplastic SMPs, respectively.

Functional Filaments: Creating and Degrading pH-Indicating PLA Filaments for 3D Printing

“…To impart enhanced mechanical properties or additional functionalities, PLA is often combined with other materials such as thermoplastic polyurethane [ 28 , 29 ], poly(ethylene glycol) [ 30 , 31 ], graphene [ 32 , 33 , 34 ], and ceramics [ 35 , 36 , 37 , 38 , 39 ]. However, when creating new PLA composites for applications such as additive manufacturing, one must not only consider the effects of the filler on the thermomechanical properties of PLA (i.e., [ 29 ]), but also the fillers’ effects on the end-product’s biodegradability.…”

In Situ Compatibilized Blends of PLA/PCL/CAB Melt-Blown Films with High Elongation: Investigation of Miscibility, Morphology, Crystallinity and Modelling

“…The development of sustainable and natural polymers-based resources as viable alternatives to fossil-based plastics has attracted much interest for many applications [ 1 , 2 , 3 , 4 , 5 , 6 ]. Polyester, such as poly( l -lactide) (PLLA), polycaprolactone (PCL), polyglycolide (PGA), and polybutylene succinate (PBS), are a versatile biodegradable family of sustainable polymers used in many applications such as food packaging, agriculture, drug delivery and medical devices [ 1 , 7 , 8 , 9 ]. There is now a growing interest in biodegradable blends with high elongation and resultant impact strength [ 10 ].…”

Generation of Controlled Micrometric Fibers inside Printed Scaffolds Using Standard FDM 3D Printers

“…A filament of polycaprolactone (PCL) (Facilan™ PCL100, 100% pure polycaprolactone homopolymer, molecular weight of 50.000 g/mol, 3D4makers.com, Haarlem, The Netherlands) was used for this purpose as it is a permeable biomaterial, which allows for a controlled drug release. It also provides shape memory, a low temperature melting point at around 60 °C, high elasticity at room temperature [ 28 ], and it is easy to print and blend with other polymers and loads [ 29 ].…”