光固化3D打印技术及光敏树脂的开发与应用

光固化3D打印技术因速度快、精度高、环境友好等优势,已成为一类广泛应用的快速成型工艺.光敏树脂作为光固化3D打印的主体材料,对器件的性能与应用有着决定性影响.本文先介绍了几种已普及和新开发的光固化3D打印成型原理;并对光敏树脂的组成、分子结构和器件性能间的构-效关系进行了分析;进而对光固化3D打印及树脂的应用进行分类介...     

3D打印用光敏树脂的高性能化及功能化研究进展

3D打印,又称增材制造,是一项新兴的智能制造技术。光固化3D打印技术是增材制造的主要方向之一,具有成型精度高、打印速度快及工艺成熟等优点。处在高速发展之中的光固化3D打印技术对光敏树脂提出了越来越高的要求,3D打印用光敏树脂的高性能及功能化研究受到极大关注。本文综述了高性能光敏树脂的最新研究进展,重点讨论了其用于构筑复杂结构导电导热聚合物、形状记忆聚合物、特殊浸润性聚合物、生物医用聚合物及凝胶材料的设计思路及相应构件所展示的优异功能性,同时对光敏树脂基3D打印材料的发展趋势及应用前景进行了分析和展望。     

DLP型3D打印用巯烯光敏树脂的制备与性能研究

基于DLP(Digital light processing)的3D打印技术因具有成型速度快、分辨率高、可打印复杂形状等优点而备受关注,开发可用于DLP型3D打印且性能优异的光敏树脂已成为研究热点。巯烯光聚合遵循自由基逐步聚合机理,相对于传统的丙烯酸酯链式聚合,巯烯聚合反应速度快、聚合网络均一、固化收缩率低。本文制备了一系列可用于DLP型3D打印的巯烯光敏树脂,探究了巯基单体含量对光敏树脂光聚合动力学、热机械性能、拉伸性能、固化收缩率和打印精度的影响。结果表明,巯基单体的加入会显著提高体系双键转化率,增加聚合网络均一性和断裂伸长率,降低固化收缩率。     

光敏树脂合成及3D打印的综合实验教学设计与实践

针对综合实验的特点,结合创新性、趣味性等特性,设计了光敏树脂合成及3D打印综合实验。实验用1,6-己二异氰酸酯(HDI)三聚体和丙烯酸羟乙酯反应,以丙烯酰吗啉(ACMO)为活性溶剂,合成可紫外光固化的预聚体树脂。通过对预聚体树脂的—NCO测定、红外光谱、核磁共振,分析了HDI三聚体和丙烯酸羟乙酯的反应程度,表征预聚体树脂的结构及评价光固化性能,并与其他光固化单体和光引发剂配合制备黏度适宜的光敏树脂。用405 nm波长的桌面级3D打印机打印出测试样条和展示样品,通过对样条性能测试,表明该光敏树脂打印的样条具有较好的力学性能。本实验开设在本科四年级的综合教学实验中,其可以使本科生学到光固化树脂的制备方法,了解化学材料与数字模型及3D打印技术的结合,体会聚合物结构与性能的关系,增强本科生对数据的分析处理能力以及拓展本科生对其他学科的知识水平。     

光固化三维打印成形材料的研究进展

光固化三维打印技术类似于喷墨打印,是一种集液滴喷射技术和分层制造技术为一体,以光敏树脂为原材料进行光固化成形的快速成形技术,具有成形精度高、成形速度快、成形温度较低、设备操作和维护简单、运行成本低等优势,这使其具有良好的发展潜力和广阔的应用前景。本文简单介绍了光固化三维打印成形技术的工作原理和发展现状,评价了该技术的优势,重点综述了光固化三维打印成形材料的特点及研究进展,并展望了未来材料的发展趋势。     

3D打印用高分子材料及其复合材料的研究进展北大核心CSCD

3D打印技术亦称为增材制造,是基于三维数学模型数据,通过连续的物理层叠加,逐层增加材料来生成三维实体的技术。作为第三次工业革命的代表性技术之一,3D打印材料是影响3D打印技术发展与应用的关健因素。而高分子聚合物在打印材料中占据主要地位,其中高分子复合材料具有明显优势。本文综述了近年来3D打印用高分子材料及其复合材料的研究现状,包括高分子丝材、光敏树脂、高分子粉末、高分子凝胶及其它高分子材料,并对高分子材料在3D打印领域的发展进行了展望。     

3D打印用高分子材料及其复合材料的研究进展

3D打印技术亦称为增材制造,是基于三维数学模型数据,通过连续的物理层叠加,逐层增加材料来生成三维实体的技术。作为第三次工业革命的代表性技术之一,3D打印材料是影响3D打印技术发展与应用的关健因素。而高分子聚合物在打印材料中占据主要地位,其中高分子复合材料具有明显优势。本文综述了近年来3D打印用高分子材料及其复合材料的研究现状,包括高分子丝材、光敏树脂、高分子粉末、高分子凝胶及其它高分子材料,并对高分子材料在3D打印领域的发展进行了展望。     

光固化3D打印教学实验设计与研究

光固化3D打印技术作为目前较为成熟的一类增材制造技术，在打印成型过程中包括三维建模、光敏树脂制备、打印参数调控、后处理等步骤，内容涉及机械、光学、高分子化学、软件工程学等相关知识。为提升本科生的实验兴趣和实验技能，进一步培养其科研和创新意识，我们面向本科生设计了基于光固化3D打印技术的创新实验。实验采用基于光引发自由基聚合的数字光处理(DLP)3D打印技术，通过对打印过程全流程的参与实践，达到让学生了解3D打印的原理、打印材料的合成和打印技术的过程等相关知识，从而达到可以自主操作完成光固化3D打印的实验教学目的。最后，通过对实验结果的分析，进一步培养学生分析问题和解决问题的能力。     

聚合物前驱体3D打印制备高性能陶瓷

3D打印制备陶瓷可以实现结构-材料设计一体化,为复杂形状陶瓷材料快速成型提供了新途径。但是传统的3D打印制备陶瓷是以陶瓷粉末或陶瓷颗粒为打印材料,存在陶瓷构件尺寸精度差、表面光洁度低和力学性能不佳等问题。近年来,以聚合物前驱体为打印材料,通过3D打印成型、高温裂解等工艺制备高性能陶瓷技术的出现为改善这些不足提供了新方法,成为3D打印陶瓷领域的研究热点。本文概述了聚合物前驱体3D打印制备高性能陶瓷的研究进展,重点阐述了本体聚合物前驱体、聚合物前驱体/光敏化合物、聚合物前驱体/巯基化合物、光敏基团改性聚合物前驱体、增强体/聚合物前驱体五种典型材料体系的研究现状,并对其今后的发展方向进行了展望。     

光固化3D打印聚酰亚胺研究进展

近年来,光固化3D打印技术因高精度、定制化、整体免装配以及快速制造等成形优点,用于解决聚酰亚胺(polyimide, PI)的微型精密、异形复杂及其功能结构一体化制造技术难题,受到了研究者的广泛研究和关注。基于光固化3D打印成形原理与PI的物理化学特性,发展了一系列光固化3D打印PI材料及其成形技术。本文归纳总结了光固化3D打印PI材料设计制备准则,重点介绍了立体光刻技术(SLA)、数字光处理技术(DLP)和紫外辅助直书写技术(UV-DIW)等光固化3D打印PI研究进展,最后通过光固化3D打印PI的应用和产业化现状提出研究发展对策。     

α-Amino acid derived enaminones and their application in the synthesis of N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates and other heterocycles

A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.     

Specific intramolecular aromatic CH insertion of diazosulfonamides

The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp³)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp²)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp²)?H and aliphatic 1,5- and 1,6-C(sp³)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp³)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp²)?H insertion.     

N-Heterocyclic carbene-palladacyclic complexes: synthesis,characterization and their applications in the C-N coupling and α-arylation of ketones using aryl chlorides

N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%).     

Iodine-mediated oxidative Pictet-Spengler reaction using terminal alkyne as the 2-oxoaldehyde surrogate for the synthesis of 1-aroyl-β-carbolines and fused-nitrogen heterocycles

An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y₁ and Y₂. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones.     

Facile synthesis of bicyclic 1-arylpyrazol-5-ones

In this Letter, we described a facile method for constructing fused bicyclic 1-arylpyrazol-5-one ring system. We employed various methylene-containing carboxylic acids as the substrates and proved that the pyrazolone ring closure requires activated methylene group in intermediate II. Accordingly, a series of structurally diversified, fused bicyclic 1-arylpyrazol-5-ones was prepared in moderate to high yields using the requisite substrates.     

A carbanion induced synthesis of highly congested pyrazole and imidazole containing heterocycles

An efficient approach to the synthesis of highly congested di, penta and hexacyclic pyrazoles as well as imidazole fragment containing novel heterocyclic molecule has been developed through a carbanion induced transformation of suitably functionalized 2H-pyran-2-ones, benzo[h]chromene and thiochromeno[4,3-b]pyrans. Due to the presence of fluorescence, we report their prime application metal sensor as off/on switching in ferric ions.     

Synthesis of pyrrolo[1,2-a]pyrazines and pyrazino[1,2-a]indoles by Curtius reaction in Morita-Baylis-Hillman derivatives

Synthesis of substituted pyrrolo[1,2-a]pyrazines and pyrazino[1,2-a]indoles from the Morita-Baylis-Hillman derivatives of acrylates via saponification followed by Curtius reaction is described.     

正丁胺对激光染料荧光谱影响的研究

用正丁胺作为碳源,采用射频辉光放电制备碳膜,选用激光染料R6G和聚乙二醇混合液作为蒸气源,采用单源热蒸发,在蒸发室与染料同时沉积得到混合膜,用拉曼光谱和红外光谱分析了碳膜的结构和键合方式,分析表明:碳膜中存在胺基团和氢原子.混合膜的荧光谱测量结果表明,认为正丁胺对染料荧光谱的影响是因为胺基和氢原子的存在.     

Selective synthesis of 4,5-dihydroimidazo- and imidazo[1,5-a]quinoxalines via modified Pictet–Spengler reaction

An efficient tandem approach for the selective synthesis of 4,5-dihydroimidazo[1,5-a]quinoxalines 6a–g and imidazo[1,5-a]quinoxalines 7a–h by the reaction of 2-imidazolyl anilines 4a–c with aryl aldehydes 5a–k under mild reaction conditions is described. Introduction of electron releasing alkyl groups in substrates 4a–b was found to be instrumental for the success of the reaction.     

Understanding the Diels-Alder reactivity of 1,2-azaborine analogues

The Diels-Alder reactivity of 1,2-heteroborines (H₄C₄B(H)X, X?=?NH, PH, AsH; O, S, Se) has been computationally explored by means of Density Functional Theory (DFT) calculations. The influence of the HB?=?X fragment on the reactivity of the system has been quantitatively analyzed in detail by means of the so-called Activation Strain Model (ASM) of reactivity. It is found that the interaction between these species and the dienophile is significantly stronger than that computed for their all-carbon isoelectronic counterpart, benzene. In addition, the strain energy plays a key role in the observed reactivity trends. The role of the aromaticity strength of these heteroarenes on the reactivity is also assessed.