微型高分子化学实验研究

高分子化学是高分子材料及相关专业重要的技术基础课。高分子化学实验是使学生进一步了解、掌握聚合物的合成、大分子反应、聚合物结构表征的基本方法和培养学生实际动手能力的重要手段。     

DOPA-PSPMA仿生共聚物综合探究性实验研究

为提高本科学生的创新创业能力,通过高分子化学实验教学使学生深入了解仿生共聚物的制备及性能的相关知识,设计了综合探究性实验。通过原子转移自由基聚合法制备仿生共聚物,并将其修饰在多种材料表面。采用X射线光电子能谱、扫描电子显微镜、生物显微镜分别对修饰材料进行表征。该实验通过共聚物的制备使学生掌握高分子化学中活性可控自由基聚合制备共聚物的方法;掌握仿生共聚物设计及构筑方法;使学生学习科研仪器的操作方法,切实提高学生的实践能力。该实验重复性好、创新性及拓展性强,将共聚物设计制备及应用有机结合,适用于高分子专业本科生综合探究性实验。     

有机化学知识在高分子材料合成创新实验中的运用——分享几个实例

针对目前教学中存在的理论课程之间、实验课程与理论课程之间关联不够紧密等问题,探索了通过"知识关联"将有机化学基本知识运用到高分子材料合成创新实验中的教学思路。以新试剂合成及应用、荧光聚酯合成、聚酰胺合成、聚酯水解等为例,介绍了如何将有机化学新理论、新方法、新试剂应用于本科高分子化学和高分子材料实验教学,以及如何将有机化学的理论知识和实验手段应用于高分子材料合成教学中。实践表明:通过"知识关联",将有机化学基础理论知识和实验技能应用于高分子合成实验中可以提高学生对所学知识的理解和运用能力,增强学生的实验探索兴趣,有效改进了高分子材料合成实验教学的课堂气氛。     

Teaching System Construction of Polymer Chemistry Experiment and its Function on Training Creative Applying Talents

高分子化学是材料化学专业重要的技术基础课,是一门以实验为基础的学科,因此,高分子化学实验是高分子科研和高分子教学的重要组成部分,是学生在掌握高分子化学的基础上,学习高分子合成的各种实验技术、聚合实施方法,培养学生进行高分子材料研究和技术开发的基本能力。从市场就业对高分子材料方向的人才需求出发,以培养创新性应用型人才为目标,通过开展实验技术讲座、改进基础性实验为综合性实验和设计性实验、增加研究性实验对高分子化学实验教学体系进行了改革,实验内容体现材料的应用性和工程价值,培养了学生的创新能力、工程实践能力。     

自由基水溶液聚合实验的改进

在高分子化学学生实验中,模仿工业生产中自由基水溶液聚合合成高分子量聚丙烯酰胺的过程,即采用氧化还原引发剂、偶氮类引发剂、过氧化物引发剂三者形成复合引发体系,在较高的单体浓度、非恒温、无搅拌的反应条件下,消耗较低的能量,高效率的聚合过程。该实验改进弥补了现有实验教材内容的空白,更有利于加深对课堂知识的理解,同时加强学生环保与节能意识,培养学生理论联系实际的能力和学生全面考虑问题的能力。     

悬浮聚合实验的教学探索

结合高分子化学实验课程的开设情况,对悬浮聚合实验的教学内容进行了探讨。在悬浮聚合实验的教学中,应充分提高学生的学习兴趣,提高教学效果,与理论课相衔接。实验的内容可以从三个方面进行改进,开展分散剂的影响研究、悬浮聚合对单体的选择和与竞聚率相结合的研究。     

高分子化学探索性实验:α,ω-羧基聚二甲基硅氧烷的可控合成

以高分子化学实验课程为载体,将学生课外科研活动与高分子化学实验以及任课教师所在科研团队的科研成果有机结合起来,把功能高分子的设计与结构表征提前引入到高分子化学实验中,形成了一整套较为完整、具有探索性和综合性的高分子化学实验实施方案。以α,ω-羧基聚二甲基硅氧烷(α,ω-羧基硅油)的可控合成为例,通过引导本科生独立地进行文献检索、实验方案设计、材料合成和结构表征及实验报告撰写,既提高了他们利用已学的有机化学和高分子化学知识进行综合分析的能力,又培养了其查阅文献、分析文献和形成创新性思维的能力。     

《高分子化学》聚合机理教学中有机化学知识的衔接利用

高分子化学是在有机化学基础上发展而成一门学科,高分子的合成反应与有机小分子的合成反应密切相关,特别是高分子合成反应机理的学习中大量应用到有机化学的基础知识.因此,在高分子化学教学中有效利用有机化学知识是帮助学生更好理解和掌握高分子化学反应机理相关知识的关键.本文根据笔者教学实践,从烯类单体聚合活性及机理、自由基聚合阻聚机理、配位聚合机理等方面以实例形式探讨了如何利用有机化学知识帮助解释高分子化学中反应活性及反应机理.     

《高分子物理实验》教学中耐候性材料老化综合性实验的设计与探究

《高分子物理实验》是高分子科学体系的重要组成部分,从事高分子研究必须掌握的基础技能。"高分子材料力学性能测定"是《高分子物理实验》中一个重要的实验项目。本文结合新疆的气候特点和新疆大学高分子材料专业的实际情况,把教师的科研成果与本科教学相结合,设计出独具特色的耐候性材料老化综合性实验。学生在实验中,不仅了解了高分子材料温差老化的作用及其对力学性能的影响,还拓宽了学生对专业的综合认识,提高学生的实际操作和分析解决问题的能力。     

基于聚酰亚胺薄膜的综合实验项目设计

以高性能聚合物材料聚酰亚胺(Polyimide,PI)为例，将目前新材料行业亟待解决的“卡脖子”问题引入本科教学中，设计了一个高分子化学综合性实验项目——聚酰亚胺薄膜制备及性能测试。项目包括高分子材料的设计、化合物合成、薄膜加工、薄膜性能表征等实验内容，涵盖分子模拟计算、图谱分析、聚合物结构与性能关系等诸多知识点。通过实验教学，让学生了解我国新材料领域的发展动态，训练其对化学及材料学科知识的综合运用能力，培养科研素养、创新意识及使命担当精神。     

Effects of experimental variables on PMMA nano-indentation measurements

This work aims to investigate the effects of experimental variables on nano-indentation measurements on PMMA. A wide range of conditions, including different load levels, loading rates, holding times and unloading rates were employed to examine the sensitivity of nano-indentation measurements to the selected experimental variables. The test results indicate that the elastic modulus and hardness of PMMA are approximately load-level invariant. However, they are sensitive to the loading rate, holding time and unloading rate. Both elastic modulus and hardness increase with increasing loading rate, while increasing holding time leads to decreasing elastic modulus and hardness. Moreover, the unloading rate has almost no obvious effect on the hardness of PMMA, while the opposite is true for elastic modulus.     

Optimization of a nitrogen analyser based on the Dumas method

The objectives of this work was to obtain a total nitrogen concentration in milk with the Dumas method for industrial and research applications. This method was faster than the Kjheldal method (5 min against 2 h or 3 h) but less precise. A three factor experimental design was performed to optimize the instrument, a FP-2000 supplied by LECO. The first interpretation of the experimental design was disappointing and no conclusion could be done. It was not a failure of experimental design but a lack of thinking on the physical and chemical aspect of the problem. Selection and construction of composite responses based on chemical and physical consideration were the keys to optimize the Dumas method. This method is now as precise as the Kjheldal method, but considerably faster.     

Role of plant alkaloids on human health: A review of biological activities

Alkaloids are plant secondary metabolite. They are well known nitrogen-containing natural bioactive compounds. Cutting edge research is going on alkaloids to unravel novel therapeutic approaches. Literature reveals that alkaloids contribute multiple biological activities and some alkaloids transform into active metabolites too. In this review, we have focused on marketed and experimental alkaloids. We have summarized sources and biological activities of reported alkaloids in past decades.     

甲基丙烯酸甲酯悬浮聚合实验教学的改进

选用氢氧化镁为分散剂,甲基丙烯酸甲酯(MMA)为单体,进行悬浮聚合反应,研究了分散剂用量、引发剂用量、水和单体比、搅拌速度、反应温度及反应时间对聚合物珠粒大小、均匀程度和产率的影响。结果表明:与目前高分子实验教材普遍选用的以聚乙烯醇(PVA)为分散剂的悬浮聚合反应相比,以氢氧化镁为分散剂,具有操作简单、聚合时间短、体系稳定性高等优点,可代替原有的悬浮聚合反应实验,作为高分子化学实验的教学课程内容。     

Optimization of lipospheres production by factorial design and their performances on a dielectrophoretic lab-on-a-chip platform

Aim of this study was to investigate the effect of the preparation parameters on the characteristics of lipospheres that would optimally fit to a lab-on-a-chip platform. Lipospheres were produced by melt dispersion technique using different lipid mixture heated to 70 °C and then emulsified into an external aqueous phase. The initial part of the work was devoted to the selection of the best lipid composition by a classical intuitive approach while the optimization and the screening of the experimental parameters were conducted through a “design of experiments”. Once the best preparation parameters were selected, they were adopted also for the production of cationic lipospheres (CLS). The second part of the study describes the analysis of the lipospheres performances when applied to a DEParray™Chip. The loading, distribution, movement and separation of neutral and cationic lipospheres were investigated. The obtained data show that both neutral and cationic lipospheres can be efficiently used in association with DEParray™Chip.     

电导法测定醋酸的电离平衡常数实验的改进

对电导法测定醋酸电离平衡常数实验做出以下改进:使用恒温水浴、改变溶液配制方法和电极使用方法。以上改进使实验结果更加准确、可靠;避免了实验中大量容量瓶的使用、清洗及润洗过程,使实验操作更加简单快捷;减少了醋酸的用量,降低实验成本;延长了电极的使用寿命;同时加深了学生对该实验原理和方法的理解。     

Effect of chromatographic parameters and detector settings on the response of HILIC-evaporative light-scattering detection system using experimental design approach and multicriteria optimization methodology

Four polar compounds, i.e. pantothenic acid, inositol, taurine and caffeine were used as probe solutes in conjunction with chemometric methods to find out meaningful implications of chromatographic conditions and detector settings on the system performance. Putting a premium on the conditions of hydrophilic interaction liquid chromatography (HILIC) and settings of evaporative light-scattering detection (ELSD), we scrutinize the importance of certain factors on signal-to-noise ratio and its variability. The application of a central composite design reveals that caffeine, which sublimes, differentiates from the relatively thermosensitive pantothenic acid as well as from inositol and taurine, which are thermostable, do not sublime and have high melting points. It seems that prior knowledge of solute characteristics is critical to estimate the chromatographic response as a function of chromatographic conditions and detection settings. Reducing the responses to just one by combining them “ad hoc”, results in an overall desirability function, which brings out the global optimal chromatographic conditions and detector settings.     

Numerical Simulation of the Effects of Experimental Error on the Higher Harmonic Components of Fourier Transformed AC Voltammograms

In this simulation study we investigate the effects of realistic levels of random and systematic experimental error in higher harmonics detected by Fourier transformed AC voltammetry for a reversible process. We show that by analyzing in the frequency domain results that are collected in the time domain, we can achieve a very large reduction in the magnitude of random (Gaussian) noise, and complete elimination of the systematic error introduced by mains frequency in both the small and large amplitude cases. As a consequence, we confirm experimental observations that even the eighth harmonic for a reversible process can be readily detected in the presence of very significant noise levels when 100 mV amplitude sine wave perturbations are employed.     

Validation of a chiral capillary electrochromatographic method for metoprolol on a teicoplanin stationary phase

Summary A chiral capillary electrochromatographic (CEC) method for determination of the enantiomeric purity of either enantiomer of metoprolol has been validated. High resolution and efficiency separations (R _s =2.5 and 80000 plates m⁻¹, respectively) were achieved by use of a teicoplanin chiral stationary phase in the polar organic mode. Method validation showed that detection linearity, robustness, accuracy, and repeatability were adequate. The method was also shown to be sufficiently sensitive for the determination of a minor enantiomer; the limit of quantitation (LOQ) was determined to be 0.09% of the peak area of the enantiomer under investigation. A similar commercial column was subsequently evaluated by use of the validated method and found to yield results for metoprolol comparable with those obtained on the homepacked columns. Acceptable separations on this commercial column were also obtained for other β-blocking drugs; those for alprenolol were particularly noteworthy (R _S =3.8 and 265000 plates m⁻¹).     

Experimental and DFT evaluation of adsorption and inhibitive properties of Moringa oliefera extract on mild steel corrosion in acidic media

The corrosion response of mild steel in 0.5 M H₂SO₄ acid solution in the presence of Moringer oliefera (MO) leaf extract was investigated using gravimetric, electrochemical, and DFT techniques. Gravimetric results indicate that MO exhibits a high inhibition value up to 93.0% when the concentration was 1.5 g/L. Inhibition value in general increased with an increase in concentration of the extracts but decreased with prolonged exposure time and temperature. Analysis of polarization curves indicated that MO extract acted as mixed-type inhibitors. The adsorption process of MO on a mild steel surface in the acid solution fitted the Langmuir isotherm. GC/MS analysis of MO extract revealed the presence of more than 29 active constituents including 9,12-Octadecadienoic acid (Z, Z) methyl ester (28.55%); n-Hexadecanoic acid (11.24%); 9,12,15-Octadecatrienoic acid methyl ester (9.31%), Benzeneacetonitrile, 4-hydroxy-(6.32%), 2-Furancarboxaldehyde,5-(hydroxymethyl)-(5.6%), Heptadecane (4.85%). Quantum chemical calculations were applied on some of the identified constituents to assess their adsorbability on the mild steel surface and the result revealed remarkable high interaction energies.