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Article ; Online: Quasi block copolymers noncovalent bonded by stereocomplex crystals

Jiali Wu / Yihang Chen / Hengti Wang / Yongjin Li

Giant, Vol 14, Iss , Pp 100150- (2023)

2023

Abstract: Self-assembly of block copolymers (BCPs) yields unparalleled opportunities to integrate exquisite characteristics for preparation of advanced nanotechnology materials. The high-yield manufacturing of BCP is extremely desired, yet rarely exploited. Herein, ...

Abstract	Self-assembly of block copolymers (BCPs) yields unparalleled opportunities to integrate exquisite characteristics for preparation of advanced nanotechnology materials. The high-yield manufacturing of BCP is extremely desired, yet rarely exploited. Herein, we displayed that stereocomplex crystals (sc) of poly lactide (PLA) enantiomers, acting as pseudo linkage between adjacent polymer chains, enable formation of quasi-block copolymer (qBCPs) by straightforward melt compounding. Identical content of poly (D-lactide) (PDLA) and poly (L-lactide) (PLLA) were pre-grafted onto the backbones of poly styrene (PS) and poly (methyl methacrylate) (PMMA), respectively. Due to the complementary multiple hydrobonding interactions between PDLA and PLLA grafted moieties, PS-“block”-PMMA connected by cocrystallized sc was induced during the subsequent melt processing of PDLA-g-PS/PLLA-g-PMMA, thus allowing local segregation of PS-“block” and PMMA-“block” with nanometer size. The refined morphology, which was resembled with micro-phase separation of classical BCP, can be facilely tuned by varying the length and ratio of enantiomeric PDLA/PLLA grafts. More interestingly, the PS-“block”-PMMA typed qBCPs demonstrated superiority in compatibilizing immiscible PS/PMMA polymer blends, as compared with the classical compatibilizer (PS-block-PMMA) via reactive blending. Overall, our strategy represents a general method to construct noncovalent linked di-block copolymer via industrially relevant melt processing, which is quite challenging to achieve by existing synthetic technologies.
Keywords	Quasi-block copolymer (qBCPs) ; Stereocomplex crystal junction ; Nanostructure ; Noncovalent compatibilization ; Science (General) ; Q1-390
Subject code	540
Language	English
Publishing date	2023-06-01T00:00:00Z
Publisher	Elsevier
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article ; Online: Effect of Tea Polyphenols on the Melt Grafting of Glycidyl Methacrylate onto Polypropylene

Xin Zheng / Lina He / Guipeng Yu / Yongjin Li

Polymers, Vol 14, Iss 5253, p

2022 Volume 5253

Abstract: It is considered to be one of the most effective strategies to prepare functionalized polypropylene (PP) materials via the melt grafting of polar monomers onto PP chains. However, the grafting efficiency of functional monomers is generally low. To ... ...

Abstract	It is considered to be one of the most effective strategies to prepare functionalized polypropylene (PP) materials via the melt grafting of polar monomers onto PP chains. However, the grafting efficiency of functional monomers is generally low. To achieve a high grafting efficiency, we explored the effect of tea polyphenols (C), which are good free radical scavengers, on the melt grafting of glycidyl methacrylate (GMA) onto PP chains initiated by dicumyl peroxide (DCP). Specifically, 0.5~3 wt% of tea polyphenols (C) were introduced to the PP/DCP/GMA melt blending system. The morphology, melt flow rate (MFR), thermal and mechanical properties of tea polyphenols (C) incorporated PP/DCP/GMA blends were investigated systematically. The results showed that the proper amount of tea polyphenols (C) (0.5~2 wt%) promoted the grafting of GMA. Unexpectedly, the PP backbone suffered from more severe degradation with the addition of tea polyphenols (C). The phenomena were ascribed to the reaction between phenolic hydroxyl groups of tea polyphenols (C) and epoxy groups of grafted GMA, which was revealed by the FTIR results. In addition, according to DSC and the tensile test, the co-grafting of GMA and tea polyphenols (C) improved the crystallization ability, yield strength and Young’s modulus of the PP matrix.
Keywords	polypropylene ; melt grafting ; glycidyl methacrylate ; tea polyphenols (C) ; co-grafting ; Organic chemistry ; QD241-441
Language	English
Publishing date	2022-12-01T00:00:00Z
Publisher	MDPI AG
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article ; Online: Enhancement of strength and toughness of bio-nanocomposites with good transparency and heat resistance by reactive processing

Hengti Wang / Chenyan Rong / Jichun You / Yongjin Li

iScience, Vol 25, Iss 7, Pp 104560- (2022)

2022

Abstract: Summary: Growing concerns in addressing environmental challenges are driving the rapid advancement of both bio-based and environmental friendly materials. Biodegradable polymers have been compounded with various nanofillers to fulfill the multiple ... ...

Abstract	Summary: Growing concerns in addressing environmental challenges are driving the rapid advancement of both bio-based and environmental friendly materials. Biodegradable polymers have been compounded with various nanofillers to fulfill the multiple requirements in real applications. However, current technologies remain to be improved in terms of the intrinsic inferior performance and the lack of interfacial interactions. In this work, we employed a facile route to develop bio-nanocomposites integrating multiple functionalities by reactive processing of polylactide and reactive boehmite nanorods. The grafting of polymer chains onto the surface of the nanorods encourages fully homogeneous dispersion of nanofillers with even 30 wt% loadings. Such nanocomposites exhibit simultaneously enhanced tensile strength, modulus, ductility, and impact strength. Moreover, the bio-based nanocomposites present promising features such as high transparency, improved flame resistance, and heat resistance. This work demonstrates exciting opportunities to produce bio-plastics with diverse functionalities in versatile applications of sustainable packaging industry and engineering plastics.
Keywords	Materials science ; Materials class ; Biomaterials ; Science ; Q
Language	English
Publishing date	2022-07-01T00:00:00Z
Publisher	Elsevier
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article ; Online: Effect of PMMA Molecular Weight on Its Localization during Crystallization of PVDF in Their Blends

Taotao Lin / Yongjin Li / Jiayao Wang / Jichun You

Polymers, Vol 13, Iss 4138, p

2021 Volume 4138

Abstract: In miscible crystalline/amorphous polymer blends, the exclusion behaviors of the latter with various molecular weights during the crystallization of the former were investigated by the combination of SAXS and DSC by taking a PVDF/PMMA blend as an example. ...

Abstract	In miscible crystalline/amorphous polymer blends, the exclusion behaviors of the latter with various molecular weights during the crystallization of the former were investigated by the combination of SAXS and DSC by taking a PVDF/PMMA blend as an example. The ratio between internal crystallinity from SAXS and overall crystallinity of the entire blend from DSC was employed to characterize the exclusion of PMMA. Our results indicate that the molecular weight of the amorphous component produces a remarkable influence on the diffusion coefficient ( D ) and the crystal growth rate ( G ) of the crystalline component. There are both inter-lamellar and inter-fibrillar structures when PVDF blended with lower-molecular-weight PMMA. With increasing molecular weight of PMMA, the decrease in crystal growth rate ( G ) dominates the enhanced exclusion behaviors of PMMA, resulting in bigger pores after extraction. Our results are significant not only for the basic understanding of crystallization in polymer blends, but also for the fabrication and structure control of porous structures based on crystallization templates.
Keywords	molecular weight ; crystallization ; exclusion ; SAXS ; DSC ; Organic chemistry ; QD241-441
Language	English
Publishing date	2021-11-01T00:00:00Z
Publisher	MDPI AG
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article ; Online: Percolation Network Formation in Nylon 6/Montmorillonite Nanocomposites

Tingzi Yan / Depei Chen / Baijin Zhao / Xiaodong Jiang / Lian Wang / Yongjin Li

Polymers, Vol 14, Iss 3672, p

A Critical Structural Insight and the Impact on Solidification Process and Mechanical Behavior

2022 Volume 3672

Abstract: The incorporation of montmorillonite (MMT) into Nylon 6 can endow advantages like improved mechanical strength and thermal stability, making Nylon 6/MMT a possible ideal alternative for Nylon 66. However, the relationship between the microstructure and ... ...

Abstract	The incorporation of montmorillonite (MMT) into Nylon 6 can endow advantages like improved mechanical strength and thermal stability, making Nylon 6/MMT a possible ideal alternative for Nylon 66. However, the relationship between the microstructure and physical properties of nylon 6/MMT nanocomposites is unclear so far due to the complicated system, including the highly asymmetric geometry of the exfoliated MMT layer and the complicated interaction between MMT layers and entangled nylon 6 chains. Herein, we focus on two processes, namely the impact of MMT on the solidification procedure during molding and the toughness–brittleness transition during the tensile stretch, in order to elucidate the structure–property relationship of nylon 6/MMT composites. We firstly studied the solidification process of nylon 6/MMT with bending height experiments. The results showed that the solidification process occurs prior to the crystallization of nylon 6, indicating that a physical crosslinked network rather than a crystalline structure is the reason for the solidification process. Furthermore, the solidification speed has a step change at around 2 wt% MMT content, indicating that the MMT percolation network is related to the transition. We further studied the influence of MMT inclusion on the mechanical properties, and found the tensile strain at break showed a similar step change at around 2 wt% MMT content, which further confirms the existence of an MMT percolation network above 2 wt% MMT content. It was generally believed that the main effect of MMT on nylon 6 is the nanofiller enforcement; we found that the percolation effect of the highly asymmetric 2-D nanofiller plays a central role in influencing the mechanical properties and solidification behavior during molding.
Keywords	nylon 6/montmorillonite nanocomposites ; percolation network ; solidification ; toughness to brittleness transition ; Organic chemistry ; QD241-441
Subject code	670
Language	English
Publishing date	2022-09-01T00:00:00Z
Publisher	MDPI AG
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article ; Online: Programmable Transition between Adhesive/Anti-Adhesive Performances on Porous PVDF Spheres Supported by Shape Memory PLLA

Jiaqin Zhao / Liang Zhang / Xiong Cheng / Jiayao Wang / Yongjin Li / Jichun You

Polymers, Vol 14, Iss 374, p

2022 Volume 374

Abstract: Superhydrophobic surfaces with switchable adhesive/anti-adhesive performances are highly desired but still challenging. Herein, by loading porous poly (vinylidene fluoride) (PVDF) spheres on a shape memory polylactic acid (PLLA) film, a quasi- ... ...

Abstract	Superhydrophobic surfaces with switchable adhesive/anti-adhesive performances are highly desired but still challenging. Herein, by loading porous poly (vinylidene fluoride) (PVDF) spheres on a shape memory polylactic acid (PLLA) film, a quasi-superhydrophobic surface of composite film (PVDF@PLLA) with the ability to tailor its surface structures/composition and related adhesive behaviors was fabricated. The as-prepared surface is covered by porous PVDF spheres. The combination of hydrophobicity of PVDF and hierarchical roughness resulted from porous spheres contributing to the high contact angle and low sliding angle, corresponding to Cassie state and lotus leaves effect. Upon uniaxial or biaxial tension, the distance among hydrophobic spheres is so high that more and more hydrophilic defects (PLLA film) have been exposed to water droplets, accounting for the quasi-superhydrophobic surface with a higher sliding angle. This is the reason for the Wenzel state and rose petals effect. After heating, PLLA film recovers to its original state. The porous PVDF spheres cover the whole film again, leading to the enhanced mobility of water droplets on the surface. The transition between the rose petals effect and the lotus leaves effect is programmable and reversible. Our result provides a novel strategy to tailor adhesive behaviors by combining (quasi-)superhydrophobic surface with shape memory effect.
Keywords	adhesive/anti-adhesive performances ; shape memory effect ; porous spheres ; PLLA ; PVDF ; Organic chemistry ; QD241-441
Subject code	620
Language	English
Publishing date	2022-01-01T00:00:00Z
Publisher	MDPI AG
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article ; Online: Enhancement of Charge Separation and NIR Light Harvesting through Construction of 2D–2D Bi4O5I2/BiOBr:Yb3+, Er3+ Z‐Scheme Heterojunctions for Improved Full‐Spectrum Photocatalytic Performance

Yongjin Li / Junhao Ma / Liang Xu / Tong Liu / Taizhong Xiao / Daomei Chen / Zhiguo Song / Jianbei Qiu / Yueli Zhang

Advanced Science, Vol 10, Iss 13, Pp n/a-n/a (2023)

2023

Abstract: Abstract Developing full‐spectrum photocatalysts with simultaneous broadband light absorption, excellent charge separation, and high redox capabilities is becoming increasingly significant. Herein, inspired by the similarities in crystalline structures ... ...

Abstract	Abstract Developing full‐spectrum photocatalysts with simultaneous broadband light absorption, excellent charge separation, and high redox capabilities is becoming increasingly significant. Herein, inspired by the similarities in crystalline structures and compositions, a unique 2D–2D Bi4O5I2/BiOBr:Yb3+,Er3+ (BI‐BYE) Z‐scheme heterojunction with upconversion (UC) functionality is successfully designed and fabricated. The co‐doped Yb3+ and Er3+ harvest near‐infrared (NIR) light and then convert it into visible light via the UC function, expanding the optical response range of the photocatalytic system. The intimate 2D–2D interface contact provides more charge migration channels and enhances the Förster resonant energy transfer of BI‐BYE, leading to significantly improved NIR light utilization efficiency. Density functional theory (DFT) calculations and experimental results confirm that the Z‐scheme heterojunction is formed and that this heterojunction endows the BI‐BYE heterostructure with high charge separation and strong redox capability. Benefit from these synergies, the optimized 75BI‐25BYE heterostructure exhibits the highest photocatalytic performance for Bisphenol A (BPA) degradation under full‐spectrum and NIR light irradiation, outperforming BYE by 6.0 and 5.3 times, respectively. This work paves an effective approach for designing highly efficient full‐spectrum responsive Z‐scheme heterojunction photocatalysts with UC function.
Keywords	Bi4O5I2/BiOBr:Yb3+,Er3+ ; full spectrum ; photocatalytic performance ; upconversion ; Z‐scheme heterojunctions ; Science ; Q
Subject code	535
Language	English
Publishing date	2023-05-01T00:00:00Z
Publisher	Wiley
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article: The emerging role of circular RNAs in spinal cord injury.

Peng Peng / Yu, Hao / Yongjin Li / Huang, Jingyuan / Yao, Shengyu / Xing, Cong / Liu, Weixiao / Zhang, Bin / Feng, Shiqing

Journal of orthopaedic translation

2021 Volume 30, Page(s) 1–5

Abstract: Spinal cord injury (SCI) is one kind of severe diseases with high mortality and morbidity worldwide, and lacks effective therapeutic interventions currently, which leads to not only permanent neurological impairments but also heavy social and economic ... ...

Abstract	Spinal cord injury (SCI) is one kind of severe diseases with high mortality and morbidity worldwide, and lacks effective therapeutic interventions currently, which leads to not only permanent neurological impairments but also heavy social and economic burden. Recent studies have proved that circRNAs are highly expressed in neural tissues, regulating the neuronal and synaptic functions. What's more, significantly altered circRNAs expression profiles are closely associated with the pathophysiology of SCI. In this review, we summarize the current advance on the role of circRNAs in SCI, which may provide a better understanding of pathogenesis and therapeutic strategies of SCI. The translational potential of this article: The Translational potential of this article is that A further understanding of circRNAs in the pathogenesis of SCI will promote the circRNA-based clinical applications.
Language	English
Publishing date	2021-07-22
Publishing country	Singapore
Document type	Journal Article ; Review
ZDB-ID	2747531-1
ISSN	2214-031X
ISSN	2214-031X
DOI	10.1016/j.jot.2021.06.001
Database	MEDical Literature Analysis and Retrieval System OnLINE

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Article ; Online: Radiation Induced Surface Modification of Nanoparticles and their Dispersion in the Polymer Matrix

Zhiang Fu / Xiaoying Gu / Lingmin Hu / Yongjin Li / Jingye Li

Nanomaterials, Vol 10, Iss 2237, p

2020 Volume 2237

Abstract: Polymer grafted inorganic nanoparticles attract significant attention, but pose challenges because of the complexity. In this work, a facile strategy to the graft polymer onto the surface of nanoparticles have been introduced. The vinyl functionalized ... ...

Abstract	Polymer grafted inorganic nanoparticles attract significant attention, but pose challenges because of the complexity. In this work, a facile strategy to the graft polymer onto the surface of nanoparticles have been introduced. The vinyl functionalized SiO 2 nanoparticles (NPs) were first prepared by the surface modification of the unmodified SiO 2 using γ-methacryloxy propyl-trimethoxylsilane. The NPs were then mixed with polyvinylidene fluoride (PVDF), which was followed by the Co-60 Gamma radiation at room temperature. PVDF molecular chains were chemically grafted onto the surface of SiO 2 nanoparticles by the linking of the double bond on the NPs. The graft ratio of PVDF on SiO 2 NPs surface can be precisely controlled by adjusting the absorbed dose and reactant feed ratio (maximum graft ratio was 31.3 wt%). The strategy is simple and it should be applied to the surface modification of many other nanoparticles. The prepared PVDF-grafted SiO 2 NPs were then dispersed in the PVDF matrix to make the nanocomposites. It was found that the modified NPs can be precisely dispersed into the PVDF matrix, as compared with pristine silica. The filling content of modifications SiO 2 NPs on the PVDF nanocomposites is almost doubled than the pristine SiO 2 counterpart. Accordingly, the mechanical property of the nanocomposites is significantly improved.
Keywords	radiation grafting ; nanoparticles ; PVDF ; silica ; dispersion ; Chemistry ; QD1-999
Subject code	620
Language	English
Publishing date	2020-11-01T00:00:00Z
Publisher	MDPI AG
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article ; Online: Investigation on the Crystallization Behaviors of Polyoxymethylene with a Small Amount of Ionic Liquid

Qi Jiao / Qin Chen / Lian Wang / Hualin Chen / Yongjin Li

Nanomaterials, Vol 9, Iss 2, p

2019 Volume 206

Abstract: Polyoxymethylene (POM) blends with excellent stiffness⁻toughness balance are successfully developed using Tributyl(octyl)phosphonium bis(trifloromethanesulfonyl) imide (TBOP-TFSI), one type of room-temperature ionic liquid, as the nucleating agent. ... ...

Abstract	Polyoxymethylene (POM) blends with excellent stiffness⁻toughness balance are successfully developed using Tributyl(octyl)phosphonium bis(trifloromethanesulfonyl) imide (TBOP-TFSI), one type of room-temperature ionic liquid, as the nucleating agent. Crystallization behaviors of POM blends have been studied by differential scanning calorimetry (DSC) and polarized light microscopy (PLM). The incorporation of TBOP-TFSI induces the crystal nucleation and fine crystal grain of POM, and also a much shorter hemi-crystalline time with only 0.5 wt% addition. The nucleation effect of ionic liquid leads to considerable improvement in the impact strength of POM blends while not sacrificing its tensile strength. Moreover, antistatic properties with a long-time stable performance are achieved by TBOP-TFSI addition as the electrical resistance reaches 10 11 Ω/sq.
Keywords	polyoxymethylene ; ionic liquid ; crystallization behavior ; nucleation ; Chemistry ; QD1-999
Subject code	669
Language	English
Publishing date	2019-02-01T00:00:00Z
Publisher	MDPI AG
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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