Dithiophosphoric Acids for Polymer Functionalization

Dithiophosphoric acids (DTPAs) are an intriguing class of compounds that are sourced from elemental sulfur and white phosphorus and are prepared from the reaction of phosphorus pentasulfide with alcohols. The electrophilic addition of DTPAs to alkenes and unsaturated olefinic substrates is a known reaction, but has not been applied to polymer synthesis and polymer functionalization. We report on the synthesis and application of DTPAs for the functionalization of challenging poly-enes, namely polyisoprene (PI) and polynorbornene (pNB) prepared by ring-opening metathesis polymerization (ROMP). The high heteroatom content within DTPA moieties impart intriguing bulk properties to poly-ene materials after direct electrophilic addition reactions to the polymer backbone introducing DTPAs as side chain groups. The resulting materials possess both enhanced optical and flame retardant properties vs the poly-ene starting materials. Finally, we demonstrate the ability to prepare crosslinked polydiene films with di-functional DTPAs, where the crosslinking density and thermomechanical properties can be directly tuned by DTPA feed ratios.     

A Space-Confined Polymerization Templated by Ice Enables Large-Scale Synthesis of Two-Dimensional Polymer Sheets

Despite significant progress in the preparation and characterization of two-dimensional (2D) materials, the synthesis of 2D organic materials remains challenging. Here, we report a novel space-confined polymerization method that enables the large-scale synthesis of 2D sheets of a functional conjugated polymer, namely, poly(3,4-ethylenedioxythiophene) (PEDOT). A key step in this method is the confinement of monomer to the boundaries of ice crystals using micelles. This spatial confinement directs the polymerization to form 2D PEDOT sheets with high crystallinity and controlled morphology. Supercapacitors prepared from the 2D PEDOT sheets exhibit outstanding performance metrics. In aqueous electrolyte, a high areal specific capacitance of 898 mF cm⁻² at 0.2 mA cm⁻² along with an excellent rate capability is achieved (e.g., capacitance retention of 67.6 % at a 50-fold higher current). Moreover, the 2D PEDOT-based supercapacitors exhibit outstanding cycling stability (capacitance retention of 98.5 % after 30,000 cycles). Device performance is further improved when an organic electrolyte is used.     

聚合物网络快离子导体

本文总结了含聚氧化乙烯(PEO)链段的聚合物网络快离子导体的研究工作,论述了这类聚合物电解质的离子导电性与网络结构的关系,并讨论了离子在其中的传递历程.通过研究聚合物网络电介质所获得的众多基本概念,同样可用于解释在PEO类高分子快离子导体研究中所发现的实验现象.     

Selective Immobilization of Gold Nanoparticles on the Surface of a Photoreactive Polymer

Summary. A photoreactive polymer containing thiocyanate (SCN) groups was employed for the immobilization of gold nanoparticles (AuNP). Upon UV illumination, isothiocyanate (NCS) groups are generated at the surface by photoisomerization. The illuminated areas of the polymer layer containing NCS were selectively modified with 2-aminoethanethiol to give SH terminated thiourea units at the surface. Gold nanoparticles were selectively immobilized in these areas by immersing the polymer surface in a colloidal solution of gold nanoparticles stabilized by citric acid. Depending on the time of immersion, different amounts of gold were deposited on the illuminated areas, while no immobilization of AuNP was observed in the non-illuminated areas. By using photolithographic masks, patterned gold structures (μm scale) were produced on the polymer surface.     

Synthesis and Characterization of a New Organic–Inorganic Hybrid Hydrogel by Using SiO2 Nanoparticles as an Initiator

A new type of organic–inorganic hybrid hydrogel (OIHH) was prepared under low air pressure using SiO₂ nanoparticles as initiator. The obtained OIHH shows a novel microstructure and characteristics, which increased the salt resistance and water absorbance. We investigate the effects of the reaction conditions on the absorption ability. The xerogel shows absorbance of 339.9 and 102.8 g/g for distilled water and for 0.9 wt% NaCl solution. Moreover, a reasonable microstructure of the superabsorbent polymer is shown.     

吸附树脂和离子交换树脂研究的新进展——介绍南开大学高分子化学研究所的部分工作

本文介绍了南开大学高分子化学研究所近年来在吸附树脂、离子交换树脂和某些具有络合基因的树脂的合成、性能和应用方面的最新研究成果。     

Highly Strong and Tough Supramolecular Polymer Networks Enabled by Cryptand-Based Host-Guest Recognition

Supramolecular polymer networks (SPNs) demonstrate great potential in the development of smart materials owing to their attractive dynamic properties. However, as they suffer from the inherent weak bonding of most noncovalent cross-links, it remains a significant challenge to construct SPNs with outstanding mechanical performance. Herein, we exploit the cryptand/paraquat host-guest recognition motifs as cross-links to prepare a class of highly strong and tough SPNs. Unlike those supramolecular cross-links with relatively weak binding abilities, the cryptand-based host-guest interactions have a high association constant and steady complexing structure, which effectively stabilizes the network and resists mechanical deformation under external force. Such favorable structural stability endows our SPNs with greatly enhanced mechanical performance, compared with the control- 1 cross-linked by the weakly complexed crown ether/secondary ammonium salt motif (tensile strength: 21.1±0.5 vs 2.8±0.1 MPa; Young's modulus: 102.6±4.8 vs 2.1±0.3 MPa; toughness: 90.4±2.0 vs 10.8±0.6 MJ m⁻³). Moreover, our SPNs also retain abundant dynamic properties including good abilities in energy dissipation, reprocessability, and stimuli-responsiveness. These findings provide novel insights into the preparation of SPNs with enhanced mechanical properties, and promote the development of high-performance intelligent supramolecular materials.     

试论高聚物结构与性能关系的三个层次

高分子物理的基本任务之一就是探求高聚物的结构与性能,揭示结构与性能之间的内在联系及其基本规律。高聚物结构与性能的关系应该包含3个层次:通过分子运动联系的"分子结构与材料性能"关系、通过产品设计联系的"凝聚态结构与制品性能"关系和通过凝聚态物理知识联系的"电子态结构与材料功能"关系。传统教材上仅讲授"结构与性能关系",有相当的局限性,需要在研究生阶段补充有关"凝聚态结构与制品性能"关系和"电子态结构与材料功能"关系的课程。     

Polymer brushes on hydrogen-terminated silicon substrates via stable Si—C bond

A universal and straightforward method for the preparation of polymer brushes via the formation of Si-C bond on silicon substrates through the UV-induced photopolymerization is demonstrated.     

高分子微凝胶控制合成无机-有机复合材料研究进展

高分子微凝胶是一类具有三维网络结构的分子内交联的高分子球形微粒,其物理、化学性质与其构象变化有着密切的关系,对于外界环境条件如温度、pH、离子强度、电场或磁场等的改变,微凝胶即表现出相应的体积相转变特性.近年来,基于高分子微凝胶对外界的刺激相应性与无机纳米粒子的特殊性能制备得到了各种有机-无机复合材料.本文根据微凝胶在无机微、纳米材料制备过程中所起的作用,将基于高分子微凝胶制备无机-有机复合微、纳米材料的方法分为原位合成法、物理诱捕法和聚合法,并分别从各类方法的特点和应用等方面进行详尽地分析和阐述.     

Polymer Chain Conformation on Deuterated Polystyrene Nanoparticles Investigated by SANS

We previously reported that grafted polystyrene (PS) chains on silica nanoparticles at a low grafting density show similar conformations to free PS chains in the same solvent, THF (diameter ?50 nm, Colloid.poly.Sci. (2013), 291, 9, 2087–2099). As an extension of our previous study we choose an organic nanoparticle (deuterated polystyrene, dPS) instead of inorganic nanoparticle to see the impact of the substrate material on chain conformation. Additionally, a wider range of molecular weights were prepared to investigate the conformation feature of grafted PS chains more in detail. Small angle neutron scattering (SANS) experiments were performed to characterize PS grafted dPS particles in good solvent condition, with deuterated toluene and deuterated THF as solvent. To get insight into the conformation of the grafted PS layer we apply a scaling law describing the dimension of free PS polymer in good solvent condition to the obtained thickness of the grafted PS layer. We find an overall agreement with the scaling law where the thickness of the grafted PS layer is slightly larger than 2R_g of the free polymer chains in the respective solvent giving hint for semi dilute polymer brush (SDPB) situation.     

以聚氨酯为基材的互穿聚合物网络

本文以对聚氨酯为基材的互穿聚合物网络的混合程度、网络形成与相分离的相关性及所得ＩＰＮ形态与性质的关系进行了评述。此处ＩＰＮ包括相容和不相容体系，这为有效地改善ＩＰＮ性质提供了依据。     

高分子相分离的分子动力学模拟

用粗粒化分子动力学(MD)模拟方法从分子层次研究两组分聚合物共混体系相分离过程中的动力学. 在相分离初期, 相区尺寸不随时间增加而变化; 在相分离中期, 相区尺寸与时间有很好的标度关系, 标度指数(α=1/3)符合Lifshiz-Slyozov提出的以扩散为主导的蒸发-凝聚机理的标度预测; 在相分离后期, 体系实现宏观相分离, 相区尺寸不再随时间改变而变化. 体积分数小的高分子链尺寸在相分离过程中先收缩再扩张, 在实现宏观相分离后, 高分子链尺寸又回到本体状态尺寸.     

邻苯二甲酸异丙酯酰氧基-丙烯酰氧基-乙酰乙酸乙酯络铝及其聚合物的合成与荧光性质

通过异丙氧基铝和邻苯二甲酸酐、乙酰乙酸乙酯及丙烯酸反应,合成了螯合物单体邻苯二甲酸异丙酯酰氧基-丙烯酰氧基-乙酰乙酸乙酯络铝,由自由基聚合法合成了聚合物,用元素分析仪、VPO、IR、¹HNMR和²⁷AlNMR证实了它们的结构,并研究了它们在DMF中的荧光性质。     

基于光热诱导红外和热重-质谱联用的聚合物成分结构剖析

材料的结构和成分是决定材料物理化学性质的关键因素,然而高分子材料成分以碳、氢、氧为主,通过成分分析很难确定材料的结构组成.红外光谱技术与热分析技术是分析高分子材料结构信息的重要表征手段.然而传统红外光谱技术对样品要求较高,很难在不破坏样品的情况下直接进行测试.本文采用一种新型光热诱导红外光谱技术在不破坏样品的前提下直接...     

用原位液体池透射电镜技术表征金属钯在球形金纳米颗粒表面的异质沉积

采用原位液体池透射电镜技术,在扫描透射电子显微镜(STEM)中,实时观察溶液中金属钯(Pd)在金(Au)纳米颗粒及团簇周围的异质沉积过程。通过对该动态过程的定量分析,结合高分辨透射电子显微镜(HRTEM)对样品进行形貌与结构表征,研究异质沉积的机理。结果表明,电子束辐照下Au-Pd异质结构纳米颗粒的形成存在两种主要机制:第一种机制中,Pd在Au纳米颗粒表面的生长是以岛状沉积开始,随着时间推移,出现Pd岛的结构弛豫和沿着Au颗粒表面的迁移扩展。伴随Pd的不断沉积和弛豫,Au-Pd复合颗粒的外接圆直径表现为震荡生长,而Au表面的Pd覆盖率显示出随时间单调增加的趋势。第二种机制中,由于Pd单体在Au纳米颗粒上的沉积位点有限,使部分被还原的Pd在Au颗粒以外区域进行同质形核与生长形成Pd团簇,之后再与Au颗粒上的Pd岛合并。进一步的结果分析显示,Au颗粒外围的Pd沉积体为多晶结构,由随机取向的Pd纳米晶粒构成。     

Effect of the Poly(Methyl Methacrylate) Molecular Weight on the Mechanical Properties BisGMA/TEGDMA Semi-interpenetrating Polymer Networks

Abstract

The effect of poly(methyl methacrylate) [PMMA], with different molecular weights on the mechanical properties of a polymerized BisGMA/TEGDMA base monomer resin was investigated. With the aid of acetone solvent, PMMA could be readily dissolved in BisGMA/TEGDMA mixtures. The addition of PMMA can significantly improve the compressive strengths and decrease the Knoop hardness values of the BisGMA/TEGDMA/PMMA semi-IPNs. The thermal expansion coefficients rapidly increased before T_g, and decreased after T _g. The observed properties could be attributed to the effect of the molecular weight of the PMMA on the phase structures of the semi-IPNs.     

Monte Carlo Simulations on Nanoparticles in Elastomers. Effects of the Particles on the Dimensions of the Polymer Chains and the Mechanical Properties of the Networks

Summary: Reinforcement of elastomers is modeled using Monte Carlo simulations on rotational isomeric state chains, to characterize their spatial configurations in the vicinity of filler particles. The resulting filler-perturbed distributions of the chain end-to-end distances are in agreement with experimental results gotten by neutron scattering. The use of these distributions in a standard molecular theory of rubberlike elasticity produces stress-strain isotherms for elongation that are consistent with available experimental results.