Guoqiang Li

Prof. Guoqiang Li

orcid
https://lsu.edu/eng/mie/people/faculty/li.php

Research Focus & Metrics

Academic Career Length

28Years (1999-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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19 September 2017 in Journal of Materials Chemistry A
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LLLu Lu
Lu Lu
JPJian Pan
Jian Pan
Guoqiang LiGuoqiang Li
Guoqiang Li
A repeatedly recyclable thermoset network with strength and stiffness similar to conventional epoxy achieved healing efficiency as high as 88.1%.

25 March 2016 in Journal of Polymer Science Part B: Polymer Physics
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Journal Article
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Guoqiang LiGuoqiang Li
Guoqiang Li
AWAnqi Wang
Anqi Wang
In this article, programming is classified as hot, warm, and cold, based on the temperature zone within which the programming is conducted. The strain and stress locking and releasing mechanisms are discussed within the thermodynamics framework. A new formula is developed for quantifying the strain recovery ratio of cold‐programmed SMPs. Stress fixity ratio and stress recovery ratio are also defined based on the understanding of stress locking and recovery mechanisms. State‐of‐the‐art literature on warm and cold programming is reviewed. Well‐controlled programming as well as free strain recovery test and constrained stress recovery test are conducted, in order to validate the memory mechanisms discussed in this study. It is found that, while programming temperature has an insignificant effect on the final free shape recovery, it has a significant effect on the stress recovery. The recovery stress programmed by cold programming may be lower, equal to, or higher than that by hot programming, due to the different stress locking mechanisms and other factors such as damage during the thermomechanical cycle.Cold, Warm, and Hot Programming of Shape Memory Polymers© 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys.2016,54, 1319–1339

10 December 2020 in ACS Applied Materials & Interfaces
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Journal Article
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XFXiaming Feng
Xiaming Feng
Guoqiang LiGuoqiang Li
Guoqiang Li
We herein report a new vitrimer system integrated with UV curability, recyclability, and flame retardancy. Energy-efficiency, sustainability, and safety have been required features for next-generation polymer materials. Various attempts have been made to endow thermoset polymers with rapid prototyping capacity, recyclability, and flame retardancy. Thermoset vitrimers based on covalent adaptable networks (CANs) are recyclable and remoldable but are generally not UV curable or flame retardant. Here, we present a conceptually novel option to achieve fast exchange reactions in CANs via catalyst-free mixed transesterification of a UV curable phosphate diester-based acrylate cross-linker. In this system, the phosphate diesters serve as reversible covalent bonds, hydrogen bonding ligands, and flame-retardant structures, while acrylate groups serve as UV curable units as well as transesterification collaborators. After the facile UV curing, an intrinsic flame-retardant and mechanically strong dynamic network was achieved due to abundant hydrogen bonds between P–OH and C═O structures. Additionally, this highly cross-linked network exhibited an attractive recyclability even at temperatures lower than Tg. This phosphate diester-based mixed transesterification concept represents an efficient approach for developing multifunctional vitrimers and can also be generalized into other thermally cured polymer systems.

16 May 2018 in Journal of Materials Chemistry A
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ALAng Li
Ang Li
JFJizhou Fan
Jizhou Fan
Guoqiang LiGuoqiang Li
Guoqiang Li
Engineering applications of current thermoset shape memory polymers are limited by three critical issues: demanding fabrication conditions (from 70 to 300 °C temperatures for hours or days), lack of reprocessability or recyclability, and low recovery stress and energy output. To address these problems simultaneously, a new UV curable and vitrimer-based epoxy thermoset shape memory polymer (VSMP) has been synthesized. A 1.1 mm thick VSMP film can be readily cured at room temperature under UV-irradiation (61 mW cm−2) in just 80 s. It possesses 36.7 MPa tensile strength, 230 MPa compressive strength, and 3120 MPa modulus at room temperature. It still has a compressive strength of 187 MPa at 120 °C. The covalent adaptable network (CAN) imparts the VSMP with recyclability, as reflected by two effective recycling cycles (>60% recycling efficiency). In addition, the VSMP exhibits good shape memory properties for multiple shape recovery cycles. With 20% compression programming strain, up to 13.4 MPa stable recovery stress and 1.05 MJ m−3 energy output in the rubbery state are achieved. With good mechanical strength, thermal stability, recyclability, and excellent shape memory properties combined with in situ UV-curing capabilities, the new VSMP is a promising multifunctional thermoset for engineering applications.

12 April 2013 in Journal of Materials Chemistry A
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HMHarper Meng
Harper Meng
Guoqiang LiGuoqiang Li
Guoqiang Li
The past decade has witnessed significant advancements in stimuli-responsive shape changing polymers. The reversible switching transition is the most important feature of stimuli-responsive polymers, which determines the shape changing effect. This article presents a comprehensive review of the various reversible switching transitions and recent progress in stimuli-responsive shape changing polymers. The advantages and limitations of the various stimuli-responsive polymers are discussed. Future research directions are suggested.

15 April 2019 in ACS Applied Materials & Interfaces
Verified
Journal Article
Closed access
XFXiaming Feng
Xiaming Feng
JFJizhou Fan
Jizhou Fan
ALAng Li
Ang Li
Guoqiang LiGuoqiang Li
Guoqiang Li