Macromolecular Engineering and Additive Manufacturing of Poly(styrene-b-isobutylene-b-styrene)

Abstract

Although polyisobutylene (PIB)-based thermoplastic elastomers (TPEs) possess a combination of unique properties (i.e., low permeability, high environmental and chemical stability, and excellent biocompatibility), they have not been explored for 3D printing. Poly­(styrene-b-isobutylene-b-styrene) (SIBS) is one of the most important PIB-based TPEs used in biomedical applications. Herein, we report, for the first time, the development of an efficient and low-cost 3D printing strategy of SIBS by fine-tuning its microstructure and properties. We discovered that blending the polystyrene (PS) homopolymer with SIBS leads to significant changes in its microphase-separated structure. The amount and molecular weight of the added PS significantly affect the micromorphology and 3D printability of SIBS/PS blends. In particular, SIBS/PS blends with high molecular weight PS at relatively high weight fractions show a unique hierarchical salami micromorphology with appropriate properties (improved hardness, modulus, and thermal stability) for 3D printing by fused filament fabrication. SIBS/PS blends with PS molecular weight close to or higher than that of SIBS show better printability than blends with low molecular weight PS. Blending the PIB block copolymer with the homopolymer of its hard block is an efficient and cost-effective strategy for additive manufacturing of PIB-based elastomers with widely tunable properties.

Macromolecular Engineering and Additive Manufacturing of Polyisobutylene‐Based Thermoplastic Elastomers. II. The Poly(styrene‐b‐isobutylene‐b‐styrene)/Poly(phenylene oxide) System

“…Filaments of SIBS/PPO blends with 1.75 mm diameter were prepared for FFF 3D printing. As we found earlier, [ 23 ] SIBS is unsuitable for FFF 3D printing due to its softness (43.7 shore A), which leads to filament buckling and extrusion failure. SIBS/PPO blends with 30–50 wt% PPO show substantially enhanced 3D printability (Table 1).…”

“…This comparative study shows that PPO has very high compatibility with SIBS, and that the addition of PPO has a similar effect on the supramolecular structure of SIBS as the addition of PS homopolymer. [ 23 ]…”

“…Figure shows representative stress–strain curves, and Table 2 summarizes the results. Compared with SIBS (which shows 13.0 MPa tensile stress, 3.4 MPa modulus, and 707% elongation at break), [ 23 ] 3D printed blends show much higher Young's modulus, improved strength, and lower elongation at break. The higher the PPO content, the higher the stress and modulus and the lower the elongation of blends.…”

“…To overcome this limitation, we have recently demonstrated the 3D printing of SIBS by blending it with polystyrene (PS). [ 23 ] SIBS/PS blends have unique molecular architectures, and their properties and 3D printability can be tuned by controlling their composition and molecular weight (MW).…”

Adhesion and Stiffness Matching in Epoxy-Vitrimers/Strain Sensor Fiber Laminates

“…A glass temperature well below room temperature is desirable for improving the mechanical properties of the matrix (faster return, less drift, in particular) but possibly worsens the Young moduli mismatch with a fiber of high modulus. In addition, the analysis of triaxiality in dog-bone-shaped specimens may be of interest in experiments involving samples with internal structuration, as, for example, 3D-printed objects described by Shen et al These authors showed that the printing angle, that is, the angle between the traveling direction of the nozzle and the long axis of the dog-bone, strongly affects the mechanical properties, especially the modulus. Triaxiality effects in the dog-bone-shaped samples could, in addition, affect the in-layer and interlayer failure modes.…”