碳酸氢钠与氯化钙溶液真的不反应吗

主要从实验与理论的角度探讨NaHCO3与CaCl2溶液是否发生反应,用大量的实验和多角度的理论进行了阐述,从中体会实验的重要性。     

介绍一种与有机宫能团对应的理论模型——基团轨道相互作用理论

自然科学的发展,总是理论与实验相互配合着发展的一个辩证过程,即实验——理论——实验,循环上升地不断发展.有机化学的发展也不例外.理论有机化学的各种观点,促使实验有机化学蓬勃发展,而旧的理论与新的实验现象之间的矛盾,又为新的理论的发展提供了素材和提出了课题.有机化学中的。电子理论”就是这样发展起来的.该理论最重要的观点之一是“电荷密度”,用这种观点曾成功地解释了不少有机化学的经验规律.但有许多实验现象仅用“电荷密度”是不能解释的,因而又出现了新的理论,其中最著名的当推Woodward-Hoffmann规则,或称“轨道对称性守恒原理”~([1]),它成功地用于解释并预言     

大学化学实验系列教材《基础化学实验：分析化学实验》

本教材由华南师范大学化学实验教学中心组织编写,汤又文主编,化学工业出版社出版,本书特色优势明显：（1）注重实验技能的训练与培养。分析化学实验基本操作的规范性和熟练程度是本课程教学的基础。（2）强调理论与实验相结合,注重实验的应用性。尽量做到理论联系实际,并结合国家标准编写部分实验。实验内容紧密联系生产生活实际,既激发学生的学习兴趣.     

实验牵引理论模式在理实一体化教学中的应用——以“酸碱滴定与电位分析”比较教学法为例

针对高职学生理论基础薄弱、对课堂传授知识的学习积极性不高等普遍现象,在酸碱滴定之后的电位分析学习过程中,通过教学改革增设综合性强的系列实验项目,如酸碱滴定理论突跃曲线(pH-V曲线)验证实验,滴定终点与化学计量点比较实验,不同方法测定水溶液酸度的比较实验等。以实验贯通酸碱滴定和电位分析重要核心内容,利用一个体系,通过几种分析方法进行比较教学,将现学的知识与已学过的知识相互连接起来,并让学生通过实验亲自动手验证理论,在熟练掌握分析操作技能的基础上提升了理论知识。     

磷酸可待因的振动光谱研究

运用密度泛函理论(DFT)计算了磷酸可待因的拉曼和红外光谱.采用B3LYP混合泛函和6-31G基函数组,同时在实验上测量了磷酸可待因的常规拉曼光谱(NRS)和红外吸收光谱(IRS),结果表明:在振动频率上理论结果与实验结果相当一致,根据理论计算的结果对磷酸可待因的振动光谱进行分析,通过理论与实验数据的比较,对磷酸可待因的所有振动谱带进行了全面地归属.     

环戊烷分子的电子动量谱

报导了在高分辨率电子动量谱仪上获得的环戊烷分子的结合能谱和动量谱的实验结果,并用Hartree-Fock方法和密度泛函方法做了理论计算.实验得到的环戊烷分子各电子轨道的电离能值与光电子谱得到的数据一致,动量分布的实验结果也与理论计算基本吻合.     

Liesegang图案实验的开发和教学实践

在无机与分析化学实验教学中引入Liesegang图案实验，并对实验不断改进，将实验操作、数值模拟与理论分析相结合，使学生认识沉淀反应中与树年轮、玛瑙石纹理和结石图案等类似的有序现象，初步了解非平衡自组织的基本现象和理论。     

高职化学实施理实一体化教学的探讨

在高职化学教学中,实施理论与实验一体化教学,将现行教学内容整合为基本操作技能、基础知识、基本应用三大模块,采用边做边学——模仿学习,先做后学——发现学习,先学后做——体验学习的教学方式,将理论教学与实验教学融为一体,以加强理论和实验之间的联系,突出专业实际的应用。     

混合气体中SAPO-34上单个物种的表面浓度简

运用Langmuir等温线方程和理想吸附溶液理论（IAST）两种方法计算了SAPO-34在混合气体中的单个物种表面浓度,并对比了计算值与实验值的吻合程度. 考察了两个二元混合体系,分别为80 ℃的甲醇和二甲醚以及25 ℃的二甲醚和乙烯混合气,发现IAST计算值在实验压力范围内均与实验结果吻合;但是Langmuir理论计算值仅在酸性位覆盖率低于1/3时与实验值吻合较好,随着压力增加严重偏离实验值,而且Langmuir理论不能描述随压力增加低饱和吸附量物种覆盖率降低的现象. 因此,针对包含不同饱和吸附量组分的混合气,Langmuir理论仅适用于描述表面浓度低时的反应动力学,当表面浓度高时应该采用IAST方法.     

碘酸铜溶度积测定实验的探讨与改进

针对碘酸铜溶度积测定实验与教学中出现的问题,引入正交设计改进实验方法,并注重实验教学与理论实际相结合,建立问题与情景教学模式。     

A novel fractional viscoelastic constitutive model for shape memory polymers

Shape memory polymers (SMPs) are a class of smart materials which can recover from a deformed shape to their original shape by a certain external stimulus. To predict the deformation behaviors of SMPs, different constitutive models have been developed in the last few years. However, most of the constitutive models need many parameters to be determined by specific experiments and complex calibration processes. This drawback has limited their application in promoting the development of SMPs. Thus, it is imperative to develop a new constitutive model which is not only accurate, but also relatively simple. In our work, a novel fractional viscoelastic constitutive model coupling with time‐temperature superposition principle is first proposed for SMPs. Then, frequency sweep and temperature sweep experiments are conducted to determine the parameters of the model. Finally, the shape memory free recovery experiments are carried out to validate the predictive capability of the developed model. By comparing the predicted results with experimental data, we find that though our model has only eleven parameters in total, it could capture the thermomechanical behaviors of SMPs in very good agreement with experimental results. We hope the proposed new model provide researchers with guidelines in designing and optimizing of SMP applications. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2018 , 56, 1125–1134     

Recent Progress in Shape Memory Polymers for Biomedical Applications

Shape memory polymers (SMPs) as one type of the most important smart materials have attracted increasing attention due to their promising application in the field of biomedicine,textiles,aerospace et al.Following a brief intoduction of the conception and classification of SMPs,this review is focused on the progress of shape memory polymers for biomedical applications.The progress includes the early researches based on thermo-induced SMPs,the improvement of the stimulus,the development of shape recovery ways and the expansion of the applications in biomedical field.In addition,future perspectives of SMPs in the field of biomedicine are also discussed.     

Fabrication of well‐defined shape memory graft polymers derived from biomass: An insight into the effect of side chain architecture on shape memory properties

Fully sustainable shape memory polymers (SMPs) derived from ethyl cellulose (EC, derived from cellulose), tetrahydrofurfuryl methacrylate (THFMA, derived from furfural), and lauryl methacrylate (LMA, derived from fatty acids) were prepared via “grafting from” atom transfer radical polymer (ATRP). The “grafting from” ATRP strategy allows to fabricate SMPs with EC as a backbone, and LMA and THFMA copolymer as a side chain. By utilizing the one‐pot and sequential monomer addition approach, two types of SMPs with random/semi‐block side chain architectures were obtained, respectively. Random/semi‐block side chain architecture of SMPs was confirmed by DSC, DMA, SAXS, and TEM. The presence of microphase separation in the SMPs with semi‐block side chain architecture provided two distinct thermal transitions, which was needed for triple‐shape memory behavior. Shape memory study showed that SMPs with semi‐block side chain architecture exhibited excellent triple‐shape memory property, and also had higher shape recovery speed and shape recovery ratio than those with random side chain architecture. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 1711–1720     

Epoxy shape memory polymer (SMP): Material preparation,uniaxial tensile tests and dynamic mechanical analysis

The utilization of epoxy shape memory polymers (SMPs) as engineering materials for deployable structures has attracted considerable attention due to their excellent thermo-mechanical endurance and satisfactory processability. Knowledge of static and dynamic mechanical properties is essential for analyzing structural behavior and recovery, especially for new epoxy SMPs. In this paper, a new epoxy SMP was prepared with epoxy and aromatic amine curing agent. Uniaxial tensile tests and digital image correlation were used to obtain static mechanical properties. Dynamic mechanical analysis was carried out to evaluate glass transition temperatures that corresponded to the heat in the recovery process.It was found that elastic modulus, Poisson’s ratio and shear modulus are 1413 MPa, 0.35 and 591 MPa, respectively. The beginning of glass transition temperature of 37.4 °C could be effectively achieved by electrical heaters, validating the shape memory properties of epoxy SMPs. In general, this study could provide useful observations and basic mechanical properties of epoxy SMPs.     

Stability and deterioration of a shape memory polymer fabric composite under thermomechanical stress

Fibres and fabrics are often used to reinforce shape memory polymers (SMPs) to improve their mechanical strength and properties, and such composites have been widely used in engineering. However incorporation of fibres and fabrics in SMPs is often accompanied with the deterioration of thermomechanical properties and shape memory effect. The thermomechanical properties and deterioration mechanisms of a shape memory polymer composite (SMPC) under repeated mechanical stress were investigated. Up to 100% extension, the SMPCs showed good shape memory effect with excellent shape recovery ratio, recovery stress and mechanical properties; while beyond that the recovery ratio and recovery stress of the composites deteriorated rapidly due to the significant delamination and debonding of fibres and fabrics from the SMP resin and accumulation of broken fibres.     

Shape memory effect and recovery stress property of carbon nanotube/waterborne epoxy nanocomposites investigated via TMA

Shape memory polymers (SMPs) have received great attention and scientific interest in widespread technological development during last few decades. Besides the development of novel SMPs, various techniques have been practiced for characterization of shape memory effect (SME) of SMPs. In this study, the shape memory effect and recovery stress property of the carbon nanotube (CNT)/waterborne epoxy (WEP) nanocomposites below and above the glass transition temperature (T_g) of the nanocomposites and under isostrain and isostress were systematically investigated via thermal mechanical analysis (TMA), respectively. The experimental results showed that the nanocomposites exhibit excellent shape memory effect. The shape memory fixity and recovery ratios were approximately 100% even below glass transition temperature (T_g). A remarkable point is that the strain of the nanocomposites suddenly increased with the temperature decreasing in a certain period of the heating-cooling cycles under isostress condition and the strain increment increased with temperature in general. Especially at low temperature, the recovery stress was very sensitive to temperature under isostrain condition of ±0.25 °C temperature with differential of 25.5 °C developed pressure difference of 0.20 MPa. Moreover, TMA is a practical method for quantifying the SME and recovery stress properties of SMPs and their composites.     

Thermo‐responsive shape memory behavior of poly(styrene‐b‐isoprene‐b‐styrene)/ethylene‐1‐octene copolymer thermoplastic elastomer blends

Thermally‐triggered shape memory polymers (SMPs) are smart materials, which are capable of changing their shapes when they are exposed a heat stimulant. Blending semi‐crystalline and elastomeric polymers is an easy and low‐cost way to obtain thermo‐responsive SMPs. In this work, novel poly(ethylene‐co‐1‐octene) (PEO) and poly(styrene‐b‐isoprene‐b‐styrene) (SIS) thermoplastic elastomer blends were prepared via melt blending method. The morphological, mechanical, rheological properties and shape memory behaviours of the blends were investigated in detail. In morphological analysis, co‐continuous morphology was found for 50 wt% PEO/50 wt% SIS and 60 wt% PEO/40 wt% SIS (60PEO/40SIS) blends. The shape memory analysis performing by dynamic mechanical analyzer showed that the 60PEO/40SIS blend also exhibited the optimum shape memory performance with 95.74% shape fixing and 98.98% shape recovery. Qualitatively shape memory analysis in hot‐water pointed out that the amount of semi‐crystalline PEO promotes shape fixing ability of the blends whereas SIS content enhances shape recovery capability. Although the SIS and PEO are immiscible polymers, the blends of them were exhibited good elastomeric properties with regard to tensile strength, toughness, and elongation at break.     

PCL-based Shape Memory Polymers with Variable PDMS Soft Segment Lengths

Thermoresponsive shape memory polymers (SMPs) are stimuli-responsive materials that return to their permanent shape from a temporary shape in response to heating. The design of new SMPs which obtain a broader range of properties including mechanical behavior is critical to realize their potential in biomedical as well as industrial and aerospace applications. To tailor the properties of SMPs, "AB networks" comprised of two distinct polymer components have been investigated but are overwhelmingly limited to those in which both components are organic. In this present work, we prepared inorganic-organic SMPs comprised of inorganic polydimethyl-siloxane (PDMS) segments of varying lengths and organic poly(ε-caprolactone) (PCL) segments. PDMS has a particularly low T(g) (-125 °C) which makes it a particularly effective soft segment to tailor the mechanical properties of PCL-based SMPs. The SMPs were prepared via the rapid photocure of solutions of diacrylated PCL(40)-block-PDMS(m)-block-PCL(40) macromers (m = 20, 37, 66 and 130). The resulting inorganic-organic SMP networks exhibited excellent shape fixity and recovery. By changing the PDMS segment length, the thermal, mechanical, and surface properties were systematically altered.     

Light‐Driven Shape‐Memory Porous Films with Precisely Controlled Dimensions

Shape‐memory polymers (SMPs) are an intriguing class of smart materials possessing reversible shape change and recovery capabilities. Effective routes to shape‐memory porous films (SMPFs) are few and limited in scope owing to the difficulty in manipulating the shape change of pores by conventional methods. Herein we report an unconventional strategy for crafting light‐driven SMPFs by judiciously constructing highly ordered porous films via a facile “breath figure” approach, followed by sequential vapor crosslinking and nondestructive directional light manipulation. Micropores can thus be transformed into other shapes including rectangle, rhombus and size‐reduced micropores at room temperature. The transformed micropores can be reverted to their original shapes by either thermal annealing or UV irradiation. As such, this strategy expands the rich diversity of SMPs accessible.     

Two-way shape memory behavior of styrene-based bilayer shape memory polymer plate

In this work, a bilayer shape memory polymer (SMP) composite plate with two-way shape memory behavior is simulated, in which two types of styrene-based SMPs with well-separated glass transition temperatures are assembled in parallel. The finite element (FE) software ABAQUS is selected to exhibit the two-way shape memory effect during the shape recovery step and the Generalized Maxwell Model with the WLF equation is applied to characterize the temperature-dependent properties of the SMP bilayer plates. The effect factors of axial predeformation, thermal expansion coefficient and plate thickness are all considered for the two-way shape memory behavior of the styrene-based bilayer SMP plate. After that, a smart gripper composed of four SMP composite plates is proposed to realize grabbing and releasing functions for one-step and staged heating recovery. The FE results provide some necessary theoretical guidelines for future soft smart structural designs and optimization.