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Author

Wang Zhang

Other affiliations: Hunan University
Bio: Wang Zhang is an academic researcher from Singapore University of Technology and Design. The author has contributed to research in topics: Materials science & Lithography. The author has an hindex of 10, co-authored 19 publications receiving 348 citations. Previous affiliations of Wang Zhang include Hunan University.

Papers
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Journal ArticleDOI
04 Jun 2020
TL;DR: This review paper summarizes a few typical applications of P μSL including mechanical metamaterials, optical components, 4D printing, bioinspired materials and biomedical applications, and offers perspectives on the directions of the further development of PμSL based 3D printing technology.
Abstract: Projection Micro Stereolithography (PμSL) is a high-resolution (up to 0.6 μm) 3D printing technology based on area projection triggered photopolymerization, and capable of fabricating complex 3D architectures covering multiple scales and with multiple materials. This paper reviews the recent development of the PμSL based 3D printing technologies, together with the related applications. It introduces the working principle, the commercialized products, and the recent multiscale, multimaterial printing capability of PμSL as well as some functional photopolymers that are suitable to PμSL. This review paper also summarizes a few typical applications of PμSL including mechanical metamaterials, optical components, 4D printing, bioinspired materials and biomedical applications, and offers perspectives on the directions of the further development of PμSL based 3D printing technology.

174 citations

Journal ArticleDOI
TL;DR: A double-network self- healing SMP (SH-SMP) system for high-resolution self-healing 4D printing, and the mechanical properties of a damaged structure can be recovered to more than 90% after adding more than 20 wt % of PCL into the SH-S MP system.
Abstract: Four-dimensional (4D) printing that enables 3D printed structures to change configurations over time has gained great attention because of its exciting potential in various applications. Among all the 4D printing materials, shape memory polymers (SMPs) possess higher stiffness and faster response rate and therefore are considered as one of most promising materials for 4D printing. However, most of the SMP-based 4D printing materials are (meth)acrylate thermosets which have permanently cross-linked covalent networks and cannot be repaired if any damage occurs. To address the unrepairable nature of SMP-based 4D printing materials, this paper reports a double-network self-healing SMP (SH-SMP) system for high-resolution self-healing 4D printing. In the SH-SMP system, the semicrystalline linear polymer polycaprolactone (PCL) is incorporated into a methacrylate-based SMP system which has good compatibility with the digital light processing-based 3D printing technology and can be used to fabricate complex 4D printing structures with high resolution (up to 30 μm). The PCL linear polymer imparts the self-healing ability to the 4D printing structures, and the mechanical properties of a damaged structure can be recovered to more than 90% after adding more than 20 wt % of PCL into the SH-SMP system. We investigated the effects of PCL concentration on the thermomechanical behavior, viscosity, and the self-healing capability of the SH-SMP system and performed the computational fluid dynamics simulations to study the effect of SH-SMP solution's viscosity on the 3D printing process. Finally, we demonstrated the self-healing 4D printing application examples to show the merits of the SH-SMP system.

110 citations

Journal ArticleDOI
TL;DR: In this paper, a shape memory polymer (SMP) photoresist based on Vero Clear achieving print features at a resolution of ~300nm half pitch using two-photon polymerization lithography (TPL).
Abstract: Four-dimensional (4D) printing of shape memory polymer (SMP) imparts time responsive properties to 3D structures. Here, we explore 4D printing of a SMP in the submicron length scale, extending its applications to nanophononics. We report a new SMP photoresist based on Vero Clear achieving print features at a resolution of ~300 nm half pitch using two-photon polymerization lithography (TPL). Prints consisting of grids with size-tunable multi-colours enabled the study of shape memory effects to achieve large visual shifts through nanoscale structure deformation. As the nanostructures are flattened, the colours and printed information become invisible. Remarkably, the shape memory effect recovers the original surface morphology of the nanostructures along with its structural colour within seconds of heating above its glass transition temperature. The high-resolution printing and excellent reversibility in both microtopography and optical properties promises a platform for temperature-sensitive labels, information hiding for anti-counterfeiting, and tunable photonic devices. Four-dimensional (4D) printing of shape memory polymer (SMP) imparts time responsive properties to 3D structures. Here, the authors explore 4D printing of a SMP in the submicron length scale, extending its applications to nanophononics.

74 citations

Journal ArticleDOI
TL;DR: A new SMP photoresist based on Vero Clear achieving print features at a resolution of ~300 nm half pitch using two-photon polymerization lithography (TPL) enabled the study of shape memory effects to achieve large visual shifts through nanoscale structure deformation.
Abstract: Four-dimensional (4D) printing of shape memory polymer (SMP) imparts time responsive properties to 3D structures. Here, we explore 4D printing of a SMP in the submicron length scale, extending its applications to nanophononics. We report a new SMP photoresist based on Vero Clear achieving print features at a resolution of ~300 nm half pitch using two-photon polymerization lithography (TPL). Prints consisting of grids with size-tunable multi-colours enabled the study of shape memory effects to achieve large visual shifts through nanoscale structure deformation. As the nanostructures are flattened, the colours and printed information become invisible. Remarkably, the shape memory effect recovers the original surface morphology of the nanostructures along with its structural colour within seconds of heating above its glass transition temperature. The high-resolution printing and excellent reversibility in both microtopography and optical properties promises a platform for temperature-sensitive labels, information hiding for anti-counterfeiting, and tunable photonic devices.

73 citations


Cited by
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01 Apr 2010
TL;DR: Polycaprolactone (PCL) was used in the biomaterials field and a number of drug-delivery devices for up to 3-4 years as discussed by the authors.
Abstract: During the resorbable-polymer-boom of the 1970s and 1980s, polycaprolactone (PCL) was used in the biomaterials field and a number of drug-delivery devices. Its popularity was soon superseded by faster resorbable polymers which had fewer perceived disadvantages associated with long term degradation (up to 3-4 years) and intracellular resorption pathways; consequently, PCL was almost forgotten for most of two decades. Recently, a resurgence of interest has propelled PCL back into the biomaterials-arena. The superior rheological and viscoelastic properties over many of its aliphatic polyester counterparts renders PCL easy to manufacture and manipulate into a large range of implants and devices. Coupled with relatively inexpensive production routes and FDA approval, this provides a promising platform for the production of longer-term degradable implants which may be manipulated physically, chemically and biologically to possess tailorable degradation kinetics to suit a specific anatomical site. This review will discuss the application of PCL as a biomaterial over the last two decades focusing on the advantages which have propagated its return into the spotlight with a particular focus on medical devices, drug delivery and tissue engineering.

480 citations

Journal ArticleDOI
Xinxin Yang1, Lizhen Guo1, Xu Xu1, Shibin Shang1, He Liu1 
TL;DR: In this paper, a fully bio-based vitrimer with a Tg above room temperature was synthesized from Epoxidized soybean oil (ESO) and a rosin derivative-fumaropimaric acid (FPA) and exhibited excellent self-healing, shape memory, and reprocessing due to the presence of dynamic covalent bond exchange.

195 citations

Journal ArticleDOI
TL;DR: The concept of associative dynamic Covalent Adaptive Networks (ADCAN) as mentioned in this paper was proposed to improve the durability and recyclability of thermoset-systems.

195 citations

Journal ArticleDOI
04 Jun 2020
TL;DR: This review paper summarizes a few typical applications of P μSL including mechanical metamaterials, optical components, 4D printing, bioinspired materials and biomedical applications, and offers perspectives on the directions of the further development of PμSL based 3D printing technology.
Abstract: Projection Micro Stereolithography (PμSL) is a high-resolution (up to 0.6 μm) 3D printing technology based on area projection triggered photopolymerization, and capable of fabricating complex 3D architectures covering multiple scales and with multiple materials. This paper reviews the recent development of the PμSL based 3D printing technologies, together with the related applications. It introduces the working principle, the commercialized products, and the recent multiscale, multimaterial printing capability of PμSL as well as some functional photopolymers that are suitable to PμSL. This review paper also summarizes a few typical applications of PμSL including mechanical metamaterials, optical components, 4D printing, bioinspired materials and biomedical applications, and offers perspectives on the directions of the further development of PμSL based 3D printing technology.

174 citations

Journal ArticleDOI
TL;DR: In this paper, a multimaterial 3D printing approach is proposed to fabricate complex hybrid 3D structures consisting of highly stretchable and high-water content acrylamide-PEGDA (AP) hydrogels covalently bonded with diverse UV curable polymers.
Abstract: Hydrogel-polymer hybrids have been widely used for various applications such as biomedical devices and flexible electronics. However, the current technologies constrain the geometries of hydrogel-polymer hybrid to laminates consisting of hydrogel with silicone rubbers. This greatly limits functionality and performance of hydrogel-polymer-based devices and machines. Here, we report a simple yet versatile multimaterial 3D printing approach to fabricate complex hybrid 3D structures consisting of highly stretchable and high-water content acrylamide-PEGDA (AP) hydrogels covalently bonded with diverse UV curable polymers. The hybrid structures are printed on a self-built DLP-based multimaterial 3D printer. We realize covalent bonding between AP hydrogel and other polymers through incomplete polymerization of AP hydrogel initiated by the water-soluble photoinitiator TPO nanoparticles. We demonstrate a few applications taking advantage of this approach. The proposed approach paves a new way to realize multifunctional soft devices and machines by bonding hydrogel with other polymers in 3D forms.

157 citations