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Gold nanoparticles with surface-anchored chiral poly（acryloyI-L（D）-valine） induce differential response on mesenchymal stem cell osteogenesis

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Nano Research 2016年第12期9卷 3683-3694页

作者： Jun Deng Honghao Zheng Xiaowen Zheng Mengyun Yao Zheng Li Changyou Gao MOE Key Laboratory of Macromolecular Synthesis and Functionalization Department of Polymer Science and Engineering ZhejiangUniversity Hangzhou 310027 China

Chirality is one of the most distinctive biochemical signatures of life, and plays crucial roles in maintaining normal functions of living cells or organisms. Pioneering work from another group has demonstrated the dependency of cell differentiation on the chirality of nano-coated substrates, but the effect of the chiral surface of nanoparticles on stem cell fates has not been investigated. In this study, the influence of molecular chiral poly（acryloyl-L（D）-valine）（L（D）- PAV）-anchored gold nanoparticles （L（D）-PAV-AuNPs） on the differentiation of mesenchymal stem cells （MSCs） was investigated. Though osteogenic differentiation of MSCs was not affected by D-PAV-AuNPs, it was significantly promoted by L-PAV-AuNPs in terms of calcium deposition, alkaline phosphatase （ALP） activity, and expression of collagen type I and osteocalcin （OCN） at both mRNA and protein levels. L-PAV-AuNPs could activate the P38 mitogen-activated protein kinase （MAPK） pathway, and may exert mechanical stress on MSCs because of high amounts of internalization. These results provide new insights on surface chirality at the nanoscale as a direct regulator to guide the differentiation of MSCs, and the use of these nanomaterials for strategic regenerative medicine.

关键词： chiralpoly（acryloyl-L（D）-valine） gold nanoparticles mesenchymal stem cells osteogenic differentiation

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synthesis of Poly[6-(2,6-bis(1＇-methylbenzimidazolyl)pyridin-4-yloxy)hexyl acrylate](PBIP) and Magnetic Property of Its Neodymium Complex(PBIP-Nd^(3＋))

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Chinese Journal of Polymer Science 2016年第7期34卷 910-917页

作者： di-zheng liu 孙维林 rong ren yan-hua wang zhi-quan shen MOE Key Laboratory of Macromolecular Synthesis and Functionalization Department of Polymer Science and Engineering Zhejiang University Hangzhou 310027 China

Homopolymer（PBIP） containing 2,6-bis（1＇-methylbenzimidazolyl）pyridine（Me BIP） ligands in the side chain was synthesized by RAFT polymerization and its kinetics was studied. Polymeric complex PBIP-Nd^3＋ was prepared by chelating PBIP with lanthanide ion Nd^3＋. The homopolymers and PBIP-Nd^3＋ complex were investigated by NMR, FTIR, GPC and TGA. The optical property of PBIP-Nd^3＋ complex was characterized by UV-Vis spectroscopy. The magnetic property of PBIP-Nd^3＋ complex was measured as a function of temperature（5 K to 300 K） and as a function of field（-3.98×10^6 A/m to 3.98×10^6 A/m）. These results indicated that PBIP-Nd^3＋ complex is paramagnetic.

关键词： 2 6-Bis（1-methylbenzimidazolyl）pyridine Magnetic RAFT Polymeric complex Neodymium

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Alignment and patterning of organic single crystals for field-effect transistors

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Chinese Chemical Letters 2016年第8期27卷 1421-1428,1471页

作者： Qin-Fen Li Shuang Liu Hong-Zheng Chen Han-Ying Li MOE Key Laboratory of Macromolecular Synthesis and Functionalization State Key Laboratory of Silicon MaterialsDepartment of Polymer Science and EngineeringZhejiang University

Organic field-effect transistors are of great importance to electronic *** the emergence of various preparation techniques for organic semiconductor materials,the device performance has been improved *** all of the organic materials,single crystals are potentially promising for high performances due to high purity and well-ordered molecular *** on organic single crystals,alignment and patterning techniques are essential for practical industrial application of electronic *** this review,recently developed methods for crystal alignment and patterning are described.

关键词： Organic single crystal Alignment Patterning Organic field-effect transistor Organic electronics

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Correlations between Kinetics and Polymer Particle Morphology in Ethylene Polymerization with Supported Ziegler-Natta Catalyst

Correlations between Kinetics and Polymer Particle Morpholog...

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The 4th Hangzhou International Polymer Forum

作者： Zhiqiang Fan Akbar Khan Meizhou Qi Pengjia Yang Zhen Zhang Yintian Guo Zhisheng Fu MOE Key Laboratory of Macromolecular Synthesis and Functionalization Department of Polymer Science and Engineering Zhejiang University

Control and optimization of nascent polymer particle morphology has been highly emphasized in industry and engineering studies of olefin polymerization. Complex correlations between the polymerization kinetics and particle morphology have been reported in the past, and different morphogenesis models have been proposed in literatures.[1,2] In this work, such correlations in different stages of ethylene slurry polymerization with MgC l2-supported Ziegler-Natta catalysts were studied. Kinetics in induction period of ethylene polymerization with a Ti Cl4/MgC l2 type Ziegler-Natta catalyst was studied by tracing the changes of polymerization rate and concentration of active centers([C*]) in the first 5-10 min. Initiation of the active centers was found to proceed in two stages. In the first 30 s [C*]/[Ti] quickly rose to about 1%, and then kept stable in the subsequent 60 s. Then the [C*]/[Ti] value started to increase again, forming the second induction stage. The polymerization activity was found to change roughly in parallel with the change of [C*]/[Ti]. Combining with the changes of the polymer/catalyst particle morphology in the induction period, a mechanistic model was proposed to explain the two-stage kinetics: initiation of active sites on the external surface of catalyst particles takes place in the first stage, and initiation of active sites buried inside the particles takes place in the second stage. These buried sites are released when the catalyst particle is disintegrated by the expanding polymer phase. Diffusion barrier by the polymer phase was considered as the main reason for decay of kp with time, and the polymer's physical properties are the main factor that decides extent of the decay. Similar disintegration of polymer/catalyst particle was observed in 1-hexene polymerization with a Ti Cl4/Di/MgC l2 type Ziegler-Natta catalyst(Di is a phthalate type internal donor). Particle morphology of ethylene slurry polymerization under 6 bar ethylene pressure wa

关键词： polyethylene kinetics particle morphology

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Kinetics of Short-term Ethylene-Propylene Copolymerization with MgCl2-supported Ziegler-Natta Catalyst

Kinetics of Short-term Ethylene-Propylene Copolymerization w...

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The 4th Hangzhou International Polymer Forum

作者： Akbar Khan Yintian Guo Zhen Zhang Zhisheng Fu Zhiqiang Fan MOE Key Laboratory of Macromolecular Synthesis and Functionalization Department of Polymer Science and Engineering Zhejiang University

Supported Ziegler-Natta（ZN） catalysts are leading in the production of polyolefins. Polymerization kinetics and mechanistic aspects of ZN catalysts in the initial stage reflect activation of the active centers. The catalyst activation will have strong impact on kinetics, particle morphology and polymer chain structure of the whole polymerization process.[1,2] In this work, kinetics of short term ethylene-propylene slurry copolymerization with MgCl-supported ZN catalysts was studied. Kinetics in induction period of ethylene-propylene copolymerization with a TiCl/MgCl type ZN catalyst was studied by tracing the changes of polymerization rate and concentration of active centers（[C*]） in the first 30 to 600 s. The polymerization activity was found to be increased in first 60 s and then became stable between 60-600 s with continuous increase of [C*]/[Ti] due to exposure of more active centers in the process. It was attributed to catalyst particle disintegration by the growing polymer phase, as more buried sites are released during the particle disintegration. The active centers released after 30 s were found to have stronger ability of incorporating propylene than those exposed（or activated） at the very beginning. The centers activated at t = 0 should locate on the external surface of catalyst particle that are the most accessible even without disintegration. These centers may have much larger steric hindrance than those exposed after the particle disintegration. The continuous increase of propylene incorporation rate with t means that, the properties of active centers exposed during the process 60-600 s also changed with time. As a result crystallinity the copolymer decreased due to [E] decreased with time. All of these behaviors were also supported by 13 C NMR analysis. Decay of Rp E and kp E with time was mainly attributed to increasing diffusion barrier by the polymer phase. Only the k and k values at very short t（30 s） are relatively closes to the true value. Furthe

关键词： Ziegler-Natta catalyst ethylene-propylene copolymerization kinetics

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Self-Assembly Amphiphilic Block Copolymers for Efficient Aqueous-Processed Hybrid Solar Cells

Self-Assembly Amphiphilic Block Copolymers for Efficient Aqu...

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The 4th Hangzhou International Polymer Forum

作者： Jun-Huan Li Jun-Ting Xu MOE Key Laboratory of Macromolecular Synthesis and Functionalization Department of Polymer Science and Engineering Zhejiang University

Due to their low cost and high efficiency, polymer/nanocrystal hybrid solar cells(HSCs) have attracted much attention in recent years. The use of water instead of toxic organic solvents during the fabrication process of these devices is capable of significantly reducing the environmental impact as well as the production cost. In aqueous-processed solar cells, HSCs employing water-soluble conjugated polymers and inorganic nanocrystals(NCs) as photovoltaic materials have gained much attention. In this work, water-soluble hybrid materials consisting of amphiphilic block copolymers(ABCPs) and Cd Te NCs were used as the active layer to fabricate the HSCs via aqueous processing. The ABCPs composed of poly(3-hexylthiophene)(P3HT) and poly(acrylic acid)(PAA) self-assembled into ordered nanostructured micelles, which then transformed to nanowires by co-micellization with P3 HT additives. Furthermore, after annealing, the hybrid materials formed an interpenetrating network, which resulted in a maximum power conversion efficiency of 4.8% in the HSCs. The properties of the hybrid materials and the film morphology were studied and correlated to the device performance. The results illustrate how the inclusion of ABCPs for directed assembly and homo-P3 HT for charge transport and light absorption improves device performance. The aqueous-processed HSCs based on the ABCPs and NCs offer an effective method for the fabrication of efficient solar cells.

关键词： self-assembly amphiphilic block copolymer aqueous-processed hybrid solar cells

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The Second Spacer Cation Assisted Growth of a 2D Perovskite Film with Oriented Large Grain for Highly Efficient and Stable Solar Cells

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Angewandte Chemie 2019年第28期131卷

作者： Xiaomei Lian Jiehuan Chen Minchao Qin Yingzhu Zhang Shuoxun Tian Xinhui Lu Gang Wu Hongzheng Chen MOE Key Laboratory of Macromolecular Synthesis and Functionalization State Key Laboratory of Silicon Materials Department of Polymer Science and Engineering Zhejiang University Hangzhou 310027 China Department of Physics The Chinese University of Hong Kong New Territories 999077 Hong Kong P. R. China

The fabrication of high‐quality film with large grains oriented along the direction of film thickness is important for 2D Ruddlesden–Popper perovskite‐based solar cells (PVSCs). High‐quality 2D BA 2 MA n −1 Pb n I 3 n +1 (BA + =butylammonium, MA + =methylammonium, n =5) perovskite films were fabricated with a grain size of over 1 μm and preferential orientation growth by introducing a second spacer cation (SSC + ) into the precursor solution. Dynamic light scattering showed that SSC + addition can induce aggregation in the precursor solution. The precursor aggregates are favorable for the formation of large crystal grains by inducing nucleation and decreasing the nucleation sites. Applying phenylethylammonium as SSC + , the optimized inverted planar PVSCs presented a maximum PCE of 14.09 %, which is the highest value of the 2D BA 2 MA n −1 Pb n I 3 n +1 ( n =5) PVSCs. The unsealed device shows good moisture stability by maintaining around 90 % of its initially efficiency after 1000 h exposure to air (Hr=25±5 %).

关键词： Energieumwandlung Große Kristallkörner Precursor-Aggregation 2D-Perowskit-Solarzellen

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Kinetics and Catalyst Morphology of 1-Hexene Polymerization with Supported Ziegler-Natta Catalyst

Kinetics and Catalyst Morphology of 1-Hexene Polymerization ...

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The 4th Hangzhou International Polymer Forum

作者： Pengjia Yang Zhisheng Fu Zhiqiang Fan MOE Key Laboratory of Macromolecular Synthesis and Functionalization Department of Polymer Science and Engineering Zhejiang University

1-Hexene was polymerized with a commercial MgCl-supported Ziegler-Natta catalyst at different monomer/catalyst mass ratio, and 2-thiophenecarbonyl chloride（TPCC） was used to quench the polymerization. The number of active centers（[C*]/[Ti]） was determined by sulfur analyzer. Polymerization rate（Rp） and propagation rate constant（kp） were calculated based on attainable monomer concentration and number of active center. [C*]/[Ti] experienced a rapid growth in the first 2 minutes, then increased gradually to a maximum value at about 10 minutes. After 10 minutes [C*]/[Ti] decreased gradually. Monomer/catalyst mass ratio had no effect on trend but higher ratio led to higher [C*]/[Ti] value. Combining with changes of catalyst morphology, the increase of [C*]/[Ti] can be explained by gradual breakage of the catalyst particles, which caused exposure of active sites buried inside. Higher monomer/catalyst mass ratio accelerated the polymerization, thus promoted the breaking of catalyst, leading to faster exposure of the buried active sites. Distribution of active centers（ACD） was investigated by deconvolution of the polymer molecular weight distribution（MWD） with multiple Schulz-Flory most-probable distributions. Four types of active center with successively decreasing molecular weight were distinguished. Changes of contents of these Flory components with time reflected variation of ACD caused by the catalyst breakage. Center A increased in the first 10 minutes, meanwhile Center D increased, indicating that active centers forming high molecular weight polymer mainly locate on the external surface of catalyst particles, while the active sites exposed by catalyst breakage produced more polymer with low molecular weight. H NMR analysis on several polymer samples was conducted for end group analysis. It showed that chain ends of the propagating chains were labeled with thiophenecarbonyl group.

关键词： supported Ziegler-Natta catalyst polyhexene-1 kinetics particle morphology

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Ethylene Polymerization with TiCl4/MgCl2 Catalysts with Different Titanium Content

Ethylene Polymerization with TiCl4/MgCl2 Catalysts with Diff...

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The 4th Hangzhou International Polymer Forum

作者： Baiyu Jiang Yuhong Weng Pengjia Yang Zhisheng Fu Zhiqiang Fan MOE Key Laboratory of Macromolecular Synthesis and Functionalization Department of Polymer Science and Engineering Zhejiang University

Ziegler-Natta catalyst, especially the supported titanium-magnesium catalysts（TMCs）, played key roles in polyolefin production in the past 30 years. Although structure of the catalysts, as well as the polymerization mechanism, has been widely studied in recent years, many questions still remain a subject of debate. Because of very high water and oxygen sensitivity and low content of active center on these catalysts, it is difficult to directly characterize the chemical structure of the active species. Therefore, it is necessary to develop a simple model catalytic system to study the composition and structure of active sites and the polymerization mechanism of the TMCs. [1-2] To solve the problem as mentioned above, we prepared a model catalyst which contains low titanium content（0.1 wt%）. Because the Ti species were mainly mononuclear and isolated, the active center distribution was effectively simplified. It will help to solve the complex mechanism in olefin polymerization. In this work, the TMCs with different Ti content were prepared by loading TiCl on MgCl particles prepared via the reaction of metallic magnesium powder with 1-chlorobutane. XRD characterization of the support showed that δ-MgCl crystallites were formed, as broad asymmetric halos appeared at 2θ≈ 32° and 2θ≈ 50°. According to the SEM images, morphologies of the support and catalyst particles were all spherical, which could prevent aggregation of polymer particles, and the size distribution was uniform. The model catalyst which contained low Ti content（0.1 wt%） showed a very high activity per gram of titanium. According to the GPC data, it was found that polyethylene produced in the initial stage of the polymerization had a significant share of low molecular weight fraction, which disappeared as the polymerization proceeded. It was assumed that the active centers producing PE of low molecular weight could be quickly activated by Al Et3 in the initial stage of polymerization. However, it deactivated

关键词： Ziegler-Natta catalyst model catalyst mononuclear ethylene

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Tailor-made Low-branched Polypropylene Prepared by a Highly Active and Robust α-Diimine Nickel Catalyst

Tailor-made Low-branched Polypropylene Prepared by a Highly ...

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The 4th Hangzhou International Polymer Forum

作者： Feng He Zhisheng Fu Zhiqiang Fan MOE Key Laboratory of Macromolecular Synthesis and Functionalization Department of Polymer Science and Engineering Zhejiang University

Living polymerizations allow for the synthesis of tailor-made polymers. Yet, there are only limited report of living propylene polymerizations. In this work, a highly active and robust α-diimine nickel catalyst prepared by our lab was used to catalyze the pseudo living polymerization of propylene, which could produce polypropylene with quite narrow PDI in high activity. Normally polypropylene（PP） is a thermoplastic polymer used in a wide variety of application. In 1995, Brookhart and other scientists synthesized bulky α-diimine Ni（Ⅱ） and palladium（Ⅱ） complex which could polymerize α-olefins to form high molecular weight polymers.1 Marked chain-walking of nickel and palladium complexes allows them to provide polyolefins with a broad spectrum of branching topologies, ranging from relatively linear to hyperbranched or dendritic. As a result, a new family of PPs has been synthesized by α-diimine nickel catalyst whose chain microstructures differ from PP produced by the early transition metal catalysts. Due to 1,3-insertion there are many ethylene-type runs（sequences of CH） in these PP chains. Living polymerizations allow for the synthesis of polymers with precisely controlled molecular weight, narrow molecular weight distribution, end-functionalized polymers, and well-defined block copolymers. So far there are only limited examples of living propylene polymerizations using α-diimine nickel catalyst. Brookhart et al. firstly reported that polymerization of propylene with the typical Brookhart cataylst at -10 ℃（1 atm, 60 min） yielded PP（M_n = 16.1×10～4） with Mw/Mn of 1.13 and T =-16 ℃ suggesting a living polymerization in 1996. Gao et al. synthesized a camphyl α-diimine nickel catalyst and used it to polymerize propylene. The resultant PPs had significantly narrow molecular weight distributions（M/M_n = 1.13 .20） in a wide temperatrue range, even at an elevated temperature of 70oC. Nevertheless, probably due to the high chain-walking ability the catalyst made PPs with low

关键词： polypropylene pseudo living polymerization α-diimine nickel catalyst

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