4D Printing of Shape‐Memory Semi‐Interpenetrating Polymer Networks Based On Aromatic Heterochain Polymers

Abstract

advent of smart materials. These materials are called smart due to their self-sensing, self-adaptability, memory capabilities and manifold functions. [1,2] Smart materials are capable of transforming their physical properties (dimensions, shape, stiffness, viscosity, adhesion, and color) following the action of different stimuli, namely, temperature, mechanical strength, electric current, light, magnetic field, chemicals, etc. [3][4][5] A combination of smart materials and 3D printing has resulted in a new field known as 4D printing. 4D printed articles may be used in different fields, including electronics, [2] aerospace industry, [1,2] engineering, [6] sensorics, [2] robotics and medicine. [7] Thermosensitive shape-memory polymers (SMPs) are the most widely studied and used group of materials. [8] In the structure of heat-sensitive SMPs, stiff segments are responsible for the retention of the permanent shape, while flexible segments are responsible for the fixation and retention of the temporary form. [8] Compared with inorganic ceramics and metallic smart materials, SMPs possess such advantages as simpler processing, chemical stability, high stress tolerance, and high recoverable strains. [4] A significant problem of the wide use of both 4D printing and 3D printing in general is a limited range of polymeric Mostof the presently known thermosensitive shape-memory polymers suitable for 4D printing have insufficient mechanical strength and thermal stability that restricts their potential areas of application. Here, new photosensitive compositions (PSCs) based on aromatic heterochain polymers -poly-N,N′-(m-phenylene)isophthalamide (MPA) or poly-2,2′-(p-oxydiphenylene)-5,5′dibenzimidazole (OPBI) -for DLP printing are proposed. Thermal post-curing and supercritical carbon dioxide (scCO 2 ) are used for post-processing of the structures. During the scCO 2 treatment the removal of unreacted monomeric component (N,N-dimethylacrylamide) and its uncrosslinked oligomers is accompanied by the preservation of the initial degree of crosslinking. The more stable shrinkage is observed for the combined post-processing method (T°+scCO 2 ) in the case of OPBI-PSC and after the heat treatment for MPA-PSC specimens. The method of post-processing and the nature of the heterochain polymer strongly affect the mechanical properties and thermal resistance of the structures. The tensile strength has the maximum value after the thermal posttreatment (101.1 ± 7.1 and 78.4 ± 5.1 MPa of OPBI-PSC and MPA-PSC, respectively). The intense destruction of the materials is observed at 393 and 408 °C for MPA-PSC and OPBI-PSC, respectively. Moreover, the 4D-printed structures exhibit excellent shape memory performance at transition temperatures >100 °C, thus have a great potential for the use in aerospace, robotics, sensorics.

Aliphatic Polybenzimidazoles: Synthesis, Characterization and High-Temperature Shape-Memory Performance

“…DMA results demonstrate that aliphatic PBIs show facile phase switching, which is important for the appearance of the shape-memory effect [ 35 ]. Similar results were observed in our previous work on shape-memory PBI-based materials [ 25 , 26 ].…”

“…However, traditional PBIs such as poly-2,2′- m -phenylene-5,5′-dibenzimidazole have highly rigid backbones and do not contain any flexible groups, so they do not possess a shape-memory effect. Previously, we showed that high-temperature SMPs could be obtained from semi-interpenetrating polymer networks based on fully aromatic poly-2,2′- p -oxydiphenylene-5,5′-dibenzimidazole (OPBI) [ 25 ]. In [ 26 ], we showed that a PBI with flexible aliphatic octamethylene fragments possesses good shape-memory ability, in contrast to poly (imide- co -benzimidazole) [ 27 ] or OPBI [ 26 ].…”

From Unregulated Networks to Designed Microstructures: Introducing Heterogeneity at Different Length Scales in Photopolymers for Additive Manufacturing

“…), heterogenization enables tailoring specific photopolymer characteristics, including optical 251 and electrical properties, 309 data storage, 310 electromagnetic absorption, 311 and shape memory. 115,312 This further emphasizes the importance of heterogenization in jewelry and decoration, dentistry, electronics, and robotics applications. 5,219,313 Stimuli-responsive polymers are a prominent example of advanced materials that can change their properties or behavior in response to specific external conditions or triggers.…”

“…Apart from the significant effect of improved toughening on usability in different industries (aerospace, automotive, medicine, etc. ), heterogenization enables tailoring specific photopolymer characteristics, including optical and electrical properties, data storage, electromagnetic absorption, and shape memory. , This further emphasizes the importance of heterogenization in jewelry and decoration, dentistry, electronics, and robotics applications. ,, …”

Soluble Fluorinated Cardo Copolyimide as an Effective Additive to Photopolymerizable Compositions Based on Di(meth)acrylates: Application for Highly Thermostable Primary Protective Coating of Silica Optical Fiber

“…There are approaches to obtain biocompatible materials by modification of implantable polyimide films [29] and polyimide covalent organic frameworks for drug delivery applications [30]. Photosensitive compositions based on aromatic heterochain polymers and reactive solvents can be used to form mechanically durable threedimensional objects by laser stereolithography [31,32], digital light processing (DLP) [33,34], and liquid crystal display (LCD) [35,36] 3D printing.…”