This research forms part of the research program of the Dutch Polymer Institute, project #749.

1.橡胶改性<ol><li>在步骤表示开始实验前准备马来酸EPM（EPM-G-MA，49％乙烯，2.1％（重量）MA，锰= 50公斤/摩尔，PDI = 2.0）橡胶和糠（FFA）1.1.1- 1.1.4。5 <ol><li>干燥在真空烘箱中的EPM-G-MA橡胶一小时在175℃至本二酸转化成酐。11 </li><li>压缩模具中热压机在150℃10分钟，100巴0.1毫米厚的橡胶膜。 </li><li>将其放置在KBr压片保持器后记录所得膜的透射红外光谱。 注:水解的二羧酸成酸酐的转换完成，如果典型的羧酸峰（ <img alt="方程" src="/files/ftp_upload/54496/54496eq_v-sCO.jpg" /> =1710厘米-1）不存在和特征环酐峰（ <img alt="方程" src="/files/ftp_upload/54496/54496eq_v-asCO.jpg" /> =1856厘米-1 </s达&gt;）存在。5 </li><li>利用标准蒸馏法玻璃器皿，蒸馏2.8克FFA（沸点= 145℃，​​28.9毫摩尔; 3.0当量基于在EPM-G-MA MA含量。）在大气压力下。 </li></ol></li><li>通过称重45.0克EPM-G-MA橡胶（9.6毫摩尔，MA），并且它在500毫升四氢呋喃（THF），在23℃下在剧烈搅拌下的封闭烧杯中溶解制备10重量％的橡胶溶液。 </li><li>添加新鲜蒸馏的FFA至10重量％的橡胶溶液2.8克</li><li>搅拌在封闭系统中，将反应混合物在23℃下至少1小时。 </li><li>通过倾倒它慢慢倒入机械搅拌下丙​​酮的十倍（5L），产生聚合物产物，很容易掏出使用大镊子烧杯白色线程沉淀反应混合物中。 </li><li>干燥收集的产物（EPM-G-呋喃）至恒重，在35℃的真空烘箱中（这需要约1天）。 </li><li>压缩模具产生的，SLIghtly在热压两个金属板之间的模具在175℃下10分钟，100巴淡黄色产物在中间马来酰胺酸产物转化成酰亚胺产物。 </li><li>切成橡胶的小块用剪刀将所得噬菌斑（0.05克）和由在丙酮中浸渍它们以除去任何未反应的FFA彻底清洗。 </li><li>记录在压缩后KBr片剂夹持模塑成0.1mm厚的膜产品的透射红外光谱。5 注:没有任何剩余的酰胺酸可从没有一个峰在1530厘米-1推断39，40为修改成功的最说明问题的指示是几乎完全消失。 <img alt="方程" src="/files/ftp_upload/54496/54496eq_v-asCO.jpg" />在酸酐的1856厘米-1和外观<img alt="方程" src="/files/ftp_upload/54496/54496eq_v-sCO.jpg" />在1710厘米-1和CN伸缩振动（ <img alt="方程" src="/files/ftp_upload/54496/54496eq_v-sCN.jpg" /> =马来酰亚胺的1378厘米-1）。 </li><li>确定的EPM-G-MA以的反应转化EPM-G-呋喃来自酸酐基团的C = O对称伸缩振动的吸收率的降低（ <img alt="方程" src="/files/ftp_upload/54496/54496eq_v-asCO.jpg" /> =1856厘米-1）通过解卷积（R 2&gt; 0.95）后积分下的各个红外（FT-IR）的峰面积。5 注:甲基摇摆振动（ <img alt="方程" src="/files/ftp_upload/54496/54496eq_rho_ip_CH3.jpg" /> =723厘米-1），从EPM骨干始发，保持在修改不变，并可以被用作内部参考。 </li><li>通过在洗涤和干燥橡胶样品进行对于N，C和H元素分析（EA）确定的变形转换。5 注意:的摩尔含量可以从测量的质量百分比得出。在EPM-G-呋喃摩尔氮含量等于接枝呋喃基。所述的EPM EPM-G-:转换可以通过在EPM-G-MA前体（7.69×10 -3）用摩尔比N，MA接枝的单体的摩尔比进行比较，以对非接枝的EPM单体来计算呋喃样本。 </li><li>测量肖氏A硬度在压缩模塑的样品的至少10倍按压硬度上的橡胶样品，覆盖硬度的整个圆柱形表面。5 注:样品厚度为2±0.1毫米应该用于这些测试。 </li><li>测量伸长率（断裂）和宽使用15mm的夹钳长度为500±50mm /分钟的应变速率在大约1mm厚5毫米的样品进行拉伸试验的极限拉伸强度。从所得stres的初始斜率确定的杨氏模量第S - 应变曲线。 注:对于每个测量，试验10个样品，并排除异常数据的最高和最低值。 </li><li>通过用厚度为6±0.1毫米（T0）和一个直径与金属板之间13±0.1mm至3/4 次他们的初始厚度（t n）的的压缩圆柱形样品确定压缩设定在23℃ 70小时，让他们在50℃半小时放松并测量厚度（T I）。 注:压缩变定值可从（叔0 -tⅰ）/（T 0 -t n）的确定。 </li></ol> 2.狄尔斯 - 阿尔德交联和后处理<ol><li>实验前，根据报道的步骤合成由didodecylamine和马来酐（MA）的脂族双马来酰亚胺（BM）41 </li><li>称取40.0克的EPM-G-呋喃橡胶（8.6毫摩尔呋喃含量）和0.04g的酚类抗牛idant（十八烷基-1- [3,5-二 - 叔丁基-4-羟基苯基]丙酸酯），并在一个大的溶解它们，在23℃下封闭烧杯用500ml THF中。 </li><li>添加1.48克脂族双马来酰亚胺（4.3毫摩尔，0.5当量基于在EPM-G-呋喃呋喃含量）与10％（重量）溶液于烧杯。 </li><li>搅拌该反应混合物在50℃下在密闭烧杯至少1小时，然后取出盖打开系统以蒸发溶剂。也可使用旋转蒸发器进行蒸发THF。 </li><li>在35℃下干燥所收集的产物至恒重，在真空烘箱中。 </li><li>压缩模在175℃，30分钟和100巴的产物。 </li><li>通过在50℃的烘箱存放为至少三天退火所得的产物。 </li><li>用剪刀剪断得到的橡胶在小片（0.05克）的斑块和通过在丙酮中浸渍它们以除去任何未反应的组分和压缩模成一个0.1mm厚˚F彻底清洗ILM。 </li><li>记录所得到的膜的透射红外光谱在KBr压片保持器，使用作为1.9.1中描述的相同设置。5 </li><li>确定在呋喃环的COC对称伸缩振动从相对减少交联的转换（ <img alt="方程" src="/files/ftp_upload/54496/54496eq_v-sCOC.jpg" />如在1.10中描述=1013厘米-1）。5 </li><li>确定由对洗涤和干燥橡胶样品对于N，C和H进行的EA的交联的转换。5 </li><li>确定肖氏A硬度，杨氏模量，断裂伸长率，极限拉伸强度和压缩在如1.12-14描述的相同的方式设置在23℃。 </li><li>通过使用剪刀切割它们切成小块重新处理试验后的样品（±50 立方毫米）和压缩在相同的条件与相同尺寸的新的，均匀的样本下成形这些。 </li></ol><ol><li>加热内部间歇式混合机至70℃，并让它旋转在50rpm。 注:初始调节步骤通过用氮气使交联过程的更好的控制冲洗腔室。 </li><li>订阅18.1克ENB-EPDM（48重量％的乙烯，5.5％（重量）ENB）的到内部间歇式混合机，达到70％的填充因数并混合2分钟，得到一均匀的熔融物。 </li><li>饲料1.25份过氧化二（叔丁基过氧异丙基）苯），或1.88份80％纯，标准，半有效硫硫化体系中，并在70℃下将其与橡胶混合3分钟。 </li><li>压缩模具中热压得到的化合物在175℃下30分钟，100巴至固化。 </li><li>确定肖氏A硬度，杨氏模量，断裂伸长率和极限抗拉强度压缩在如1.12-14描述的相同的方式设置。 </li></ol> 4.ç罗斯 - 链路密度测定<ol><li>切一块约50毫克用剪刀压缩成型，交联的橡胶。 <ol><li>正是通过称量其在20ml的玻璃小瓶（W 0）确定的橡胶样品的初始重量。 </li><li>浸泡称量橡胶在15ml萘烷中。 </li></ol></li><li>让橡胶在萘烷溶胀直到其重量不再增加，当达到（约3天）平衡溶胀。 </li><li>小心地溶胀样品从瓶中，并仔细用薄纸轻拍表面以从表面去除任何溶剂而不挤压它。 </li><li>称量溶胀橡胶样品中的新的样品瓶（W 1）。 </li><li>在80℃干燥在真空烘箱中溶胀样品，直到达到恒重，并测定样品的干重量（W 2）。 </li><li>获得W 2 / W 0×100％的凝胶含量</li><li>确定交叉联密度（[XLD]在摩尔/厘米3）使用的Flory-Rehner公式42，43，[XLD] =（LN（1-V R）+ V R +χVR 2）/（2V S（0.5Vř -Vř1/3））采用V S上的溶剂（萘烷的摩尔体积:在23℃154毫升/摩尔），χ相互作用参数（萘烷-EPDM:0.121 + 0.278V R 44）和V R中的用为860千克/米3的密度（ρ）橡胶溶胀样品中，可以从W 2 /（W 2 +（W 1 -W 2）∙ρEPM-G-呋喃 /ρ 萘烷 ）来测定的体积分数EPM-G-呋喃和896公斤/米3为萘烷，分别。 </li></ol>

The author Martin van Duin is an employee of LANXESS Elastomers B.V. that produces EPM-g-MA rubbers used in this Article.

商业EPM-G-MA橡胶是热可逆的交联在一个简单的两步骤方法。该马来化的橡胶首先用FFA改性接枝呋喃基到橡胶骨架。所得未决呋喃显示反应性狄尔斯 - 阿尔德二烯。脂族的BM被用作交联剂，得到两个呋喃部分之间的热可逆桥。两个反应均成功使用根据红外光谱，元素分析好的转换（&gt; 80％）。交联是通过溶胀和溶解性试验，得到100％的凝胶含量示出。 为描述的协议的成功执行，...

硫磺硫化和过氧化物固化是目前在橡胶工业中的主要工业交联技术，产生不可逆的化学交联，以防止熔融后处理:1，2 A&#39;摇篮到摇篮"的方式回收交联的橡胶，需要一种材料表现在提供服务的条件类似于永久交联的橡胶，而具有热塑性的高温下的加工性和完整的可回收性。要达到这样的可回收的方法使用与该对外部刺激作出反应的可逆交联，如温度（从未来的工业应用的观点出发最可行的）的橡胶状网络。3-5这些交联的以相对较低的服务的形成温度是必需的橡胶的良好的机械特性，而在高温下（类似于原始的非交联的化合物的处理温度）的裂解允许当r该材料的ecycling。 一些具体的材料可以是可逆地通过经由缩聚反应6或通过所谓的可逆网络拓扑利用所谓的动态共价网络经由酯交换反应冷冻交联的。7-9这些方法的缺点是设计的必要性和合成新的聚合物，而不是修改已经具有所需性质的现有商业橡胶。技术来热-可逆交联橡胶涉及氢键，离子相互作用和共价键，如通过热活化的二硫化物重排。10-13最近，热可逆交联通过狄尔斯-阿尔德（DA）的化学开发的。14 -21 DA化学可以应用于范围广泛的聚合物，并代表一个流行的选择，特别是因为对DA反应允许相对快的动力学和反应条件温和。17，22-24钍EIR低耦合和高的去耦的温度使呋喃和马来酰亚胺优良候选可逆聚合物交联。18-20，25-28 本工作的目的是提供一种用于使用DA化学作为用于工业橡胶产品（ 图1）的热可逆交联的工具的方法。5首先，饱和烃类弹性体，如乙烯的反应性/丙烯橡胶（EPM），必须增加。促进这方面的一个商业相关的例子是马来酸酐（MA）的过氧化物引发自由基接枝29-34其次，呋喃组可以通过插入糠（FFA）插入挂件酸酐接枝到这样一种马来EPM橡胶以形成酰亚胺。35，36最后，从而被附接到橡胶骨架上的呋喃基部分可以再参加热可逆DA化学作为富电子二烯。25，37的电子婆或双-马来酰亚胺（BM）是该交联反应的合适的亲二烯体。19，26，38 <img alt="图1" src="/files/ftp_upload/54496/54496fig1.jpg" /> 图1. 反应方案。呋喃嫁接和EPM-G-MA橡胶（从5许可转载）双马来酰亚胺的交联。 <a href="http://www.jove.com/files/ftp_upload/54496/54496fig1large.jpg" target="_blank">请点击此处查看该图的放大版本。</a>

<table border="0" cellpadding="0" cellspacing="0" width="599">
	<tbody>
		<tr height="63">
			<td height="63" style="height:63px;width:216px;">ENB-EPDM</td>
			<td style="width:97px;">LANXESS Elastomers B.V.</td>
			<td style="width:119px;">Keltan 8550C</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:216px;">EPM-g-MA</td>
			<td style="width:97px;">LANXESS Elastomers B.V.</td>
			<td>Keltan DE5005</td>
			<td>Vacuum oven for one hour at 175 &#176;C&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">furfurylamine</td>
			<td style="width:97px;">Sigma-Aldrich</td>
			<td style="width:119px;">F20009</td>
			<td>Freshly distillated before use</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">di-dodecylamine</td>
			<td style="width:97px;">Sigma-Aldrich</td>
			<td style="width:119px;">36784</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">maleic anhydride</td>
			<td style="width:97px;">Sigma-Aldrich</td>
			<td style="width:119px;">M0357</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">octadecyl-1-(3,5-di-tert.-butyl-4-hydroxyphenyl)propionate</td>
			<td style="width:97px;">Sigma-Aldrich</td>
			<td style="width:119px;">367079</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">bis(tert.-butylperoxy-iso-propyl) benzene</td>
			<td style="width:97px;">Sigma-Aldrich</td>
			<td style="width:119px;">531685</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">tetrahydrofuran</td>
			<td style="width:97px;">Sigma-Aldrich</td>
			<td style="width:119px;">401757</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">decalin</td>
			<td style="width:97px;">Sigma-Aldrich</td>
			<td style="width:119px;">294772</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">acetone</td>
			<td style="width:97px;">Sigma-Aldrich</td>
			<td style="width:119px;">320110</td>
			<td></td>
		</tr>
	</tbody>
</table>

the preparation and properties of thermo-reversibly cross-linked rubber via diels-alder chemistry

论证一种利用狄尔斯阿尔德热可逆化学为橡胶制品交联方法工具。在这项工作中，一个商用乙烯 - 丙烯橡胶，马来酸酐接枝，是热可逆分两步交联的。挂起的酸酐部分首先与糠胺接枝呋喃基的橡胶主链改性。这些挂件呋喃基是然后经由狄尔斯 - 阿尔德偶联反应的双 - 马来酰亚胺交联的。两个反应可以在广泛的实验条件下进行，并且可以很容易地在大范围的应用。所得狄尔斯 - 阿尔德交联橡胶的材料性质类似于过氧化物固化的乙烯/丙烯/二烯橡胶（EPDM）参考。该交联通过复古Diels-Alder反应在升高的温度下破裂（&gt; 150℃），并且可以通过在较低温度下热退火（50-70℃）进行改革。该系统的可逆性被证明机智ħ红外光谱，溶解度试验和机械性能。该材料的可回收也显示在一个实际的方式， 也就是说，通过切割的交联样品分成小份并压缩它们成型为新的样本显示可比的机械性能，这是不可能的常规交联的橡胶。

EPM-G-MA的成功修饰成EPM-G-呋喃和交联与双马来酰亚胺由傅立叶所示变换红外光谱（FTIR）（ 图2）。呋喃基的在EPM-G-呋喃产物的存在可以从CC脂族伸缩峰的分裂（推断<img alt="方程" src="/files/ftp_upload/54496/54496eq_v-sCC.jpg" /> =1050厘米-1）分为两个呋喃峰（ <img alt="方程" src="/files/ftp_upload/54496/54496eq_v-asCOC.jpg" /> =1073厘米-1 <img alt="方程" src="/files/ftp_upload/544...

Watch this Scientific Journal Video about The Preparation and Properties of Thermo-reversibly Cross-linked Rubber Via Diels-Alder Chemistry at JoVE.com

The Preparation and Properties of Thermo-reversibly Cross-linked Rubber Via Diels-Alder Chemistry

A simple two-step approach involving rubber modification and cross-linking yields fully reworkable, elastic rubber products.

热可逆交联橡胶通过的Diels-Alder反应的化学制备与性能

A method for using Diels Alder thermo-reversible chemistry as cross-linking tool for rubber products is demonstrated. In this work, a commercial ...

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13.5K 次观看.  University of Groningen. A simple two-step approach involving rubber modification and cross-linking yields fully reworkable, elastic rubber products. 

视频: The Preparation and Properties of Thermo-reversibly Cross-linked Rubber Via Diels-Alder Chemistry

Microwave-assisted Intramolecular Dehydrogenative Diels-Alder Reactions for the Synthesis of Functionalized Naphthalenes/Solvatochromic Dyes

Functionalized naphthalenes have applications in a variety of research fields ranging from the synthesis of natural or biologically active molecules to the preparation of new organic dyes. Although numerous strategies have been reported to access naphthalene scaffolds, many procedures still present limitations in terms of incorporating functionality, which in turn narrows the range of available substrates. The development of versatile methods for direct access to substituted naphthalenes is therefore highly desirable.
The Diels-Alder (DA) cycloaddition reaction is a powerful and attractive method for the formation of saturated and unsaturated ring systems from readily available starting materials. A new microwave-assisted intramolecular dehydrogenative DA reaction of styrenyl derivatives described herein generates a variety of functionalized cyclopenta[b]naphthalenes that could not be prepared using existing synthetic methods. When compared to conventional heating, microwave irradiation accelerates reaction rates, enhances yields, and limits the formation of undesired byproducts.
The utility of this protocol is further demonstrated by the conversion of a DA cycloadduct into a novel solvatochromic fluorescent dye via a Buchwald-Hartwig palladium-catalyzed cross-coupling reaction. Fluorescence spectroscopy, as an informative and sensitive analytical technique, plays a key role in research fields including environmental science, medicine, pharmacology, and cellular biology. Access to a variety of new organic fluorophores provided by the microwave-assisted dehydrogenative DA reaction allows for further advancement in these fields.

Microwave-assisted intramolecular dehydrogenative Diels-Alder (DA) reactions provide concise access to functionalized cyclopenta[b]naphthalene building blocks. The utility of this methodology is demonstrated by one-step conversion of the dehydrogenative DA cycloadducts into novel solvatochromic fluorescent dyes via Buchwald-Hartwig palladium-catalyzed cross-coupling reactions.

微波辅助分子内Diels-Alder反应的功能化萘/变色染料的合成脱氢

Functionalized naphthalenes have applications in a variety of research fields ranging from the synthesis of natural or biologically active molecules to ...

科研

化学

Preparation of Hydrophobic Metal-Organic Frameworks via Plasma Enhanced Chemical Vapor Deposition of Perfluoroalkanes for the Removal of Ammonia

Plasma enhanced chemical vapor deposition (PECVD) of perfluoroalkanes has long been studied for tuning the wetting properties of surfaces. For high surface area microporous materials, such as metal-organic frameworks (MOFs), unique challenges present themselves for PECVD treatments. Herein the protocol for development of a MOF that was previously unstable to humid conditions is presented. The protocol describes the synthesis of Cu-BTC (also known as HKUST-1), the treatment of Cu-BTC with PECVD of perfluoroalkanes, the aging of materials under humid conditions, and the subsequent ammonia microbreakthrough experiments on milligram quantities of microporous materials. Cu-BTC has an extremely high surface area (~1,800 m2/g) when compared to most materials or surfaces that have been previously treated by PECVD methods. Parameters such as chamber pressure and treatment time are extremely important to ensure the perfluoroalkane plasma penetrates to and reacts with the inner MOF surfaces. Furthermore, the protocol for ammonia microbreakthrough experiments set forth here can be utilized for a variety of test gases and microporous materials.

Herein the procedures for plasma enhanced chemical vapor deposition of perfluoroalkanes on microporous materials such as metal-organic frameworks to enhance their stability and hydrophobicity are described. Furthermore, breakthrough testing of milligram quantities of samples is described in detail.

增强型氟烷烃的化学气相沉积等离子通过疏水金属 - 有机骨架的制备氨的去除

Plasma enhanced chemical vapor deposition (PECVD) of perfluoroalkanes has long been studied for tuning the wetting properties of surfaces. For high ...

Preparation and Use of Carbonyl-decorated Carbenes in the Activation of White Phosphorus

Here we present a protocol for the synthesis of two distinct carbonyl-decorated carbenes. Both carbenes can be prepared using nearly identical procedures in multi-gram scale quantities. The goal of this manuscript is to clearly detail how to handle and prepare these unique carbenes such that a synthetic chemist of any skill level can work with them. The two carbenes described are a diamidocarbene (DAC, carbene 1) and a monoamidoaminocarbene (MAAC 2). These carbenes are highly electron-deficient and as such display reactivity profiles that are atypical of more traditional N-heterocyclic carbenes. Additionally, these two carbenes only differ in their electrophilic character and not their steric parameters, making them ideal for studying how carbene electronics influence reactivity. To demonstrate this phenomenon, we are also describing the activation of white phosphorus (P4) using these carbenes. Depending on the carbene used, two very different phosphorus-containing compounds can be isolated. When the DAC 1 is used, a tris(phosphaalkenyl)phosphane can be isolated as the exclusive product. Remarkably however, when MAAC 2 is added to P4 under identical reaction conditions, an unexpected carbene-supported P8&#160;allotrope of phosphorus is isolated exclusively. Mechanistic studies demonstrate that this carbene-supported P8allotrope forms via a [2+2] cycloaddition dimerization of a transient diphosphene which has been trapped by treatment with 2,3-dimethyl-1,3-butadiene.

Here, we present a protocol for the synthesis of two carbonyl-decorated carbenes. The protocol makes these interesting compounds readily available to chemists of all skill levels. In addition to the synthesis of these two carbenes, their use in the activation of white phosphorus is also described.

羰基饰卡宾的白色磷的活化制备方法和用途

Here we present a protocol for the synthesis of two distinct carbonyl-decorated carbenes. Both carbenes can be prepared using nearly identical procedures ...

Facile and Efficient Preparation of Tri-component Fluorescent Glycopolymers via RAFT-controlled Polymerization

Synthetic glycopolymers are instrumental and versatile tools used in various biochemical and biomedical research fields. An example of a facile and efficient synthesis of well-controlled fluorescent statistical glycopolymers using reversible addition-fragmentation chain-transfer (RAFT)-based polymerization is demonstrated. The synthesis starts with the preparation of &#946;-galactose-containing glycomonomer 2-lactobionamidoethyl methacrylamide obtained by reaction of lactobionolactone and N-(2-aminoethyl) methacrylamide (AEMA). 2-Gluconamidoethyl methacrylamide (GAEMA) is used as a structural analog lacking a terminal &#946;-galactoside. The following RAFT-mediated copolymerization reaction involves three different monomers: N-(2-hydroxyethyl) acrylamide as spacer, AEMA as target for further fluorescence labeling, and the glycomonomers. Tolerant of aqueous systems, the RAFT agent used in the reaction is (4-cyanopentanoic acid)-4-dithiobenzoate. Low dispersities (&#8804;1.32), predictable copolymer compositions, and high reproducibility of the polymerizations were observed among the products. Fluorescent polymers are obtained by modifying the glycopolymers with carboxyfluorescein succinimidyl ester targeting the primary amine functional groups on AEMA. Lectin-binding specificities of the resulting glycopolymers are verified by testing with corresponding agarose beads coated with specific glycoepitope recognizing lectins. Because of the ease of the synthesis, the tight control of the product compositions and the good reproducibility of the reaction, this protocol can be translated towards preparation of other RAFT-based glycopolymers with specific structures and compositions, as desired.

An efficient, three-step synthesis of RAFT-based fluorescent glycopolymers, consisting of glycomonomer preparation, copolymerization, and post-modification, is demonstrated. This protocol can be used to prepare RAFT-based statistical glycopolymers with desired structures.

通过RAFT控制聚合轻便和高效制备三组分荧光Glycopolymers

Synthetic glycopolymers are instrumental and versatile tools used in various biochemical and biomedical research fields. An example of a facile and ...

Synthesis of Protein Bioconjugates via Cysteine-maleimide Chemistry

The chemical linking or bioconjugation of proteins to fluorescent dyes, drugs, polymers and other proteins has a broad range of applications, such as the development of antibody drug conjugates (ADCs) and nanomedicine, fluorescent microscopy and systems chemistry. For many of these applications, specificity of the bioconjugation method used is of prime concern. The Michael addition of maleimides with cysteine(s) on the target proteins is highly selective and proceeds rapidly under mild conditions, making it one of the most popular methods for protein bioconjugation.
We demonstrate here the modification of the only surface-accessible cysteine residue on yeast cytochrome c with a ruthenium(II) bisterpyridine maleimide. The protein bioconjugation is verified by gel electrophoresis and purified by aqueous-based fast protein liquid chromatography in 27% yield of isolated protein material. Structural characterization with MALDI-TOF MS and UV-Vis is then used to verify that the bioconjugation is successful. The protocol shown here is easily applicable to other cysteine - maleimide coupling of proteins to other proteins, dyes, drugs or polymers.

Synthesis of Protein Bioconjugates via Cysteine-maleimide Chemistry

This protocol details the important steps required for the bioconjugation of a cysteine containing protein to a maleimide, including reagent purification, reaction conditions, bioconjugate purification and bioconjugate characterization.

蛋白质生物缀合物的合成<em&gt;通过</em&gt;半胱氨酸马来酰亚胺化学

The chemical linking or bioconjugation of proteins to fluorescent dyes, drugs, polymers and other proteins has a broad range of applications, such as the ...

Preparation of Chitosan-based Injectable Hydrogels and Its Application in 3D Cell Culture

The protocol presents a facile, efficient, and versatile method to prepare chitosan-based hydrogels using dynamic imine chemistry. The hydrogel is prepared by mixing solutions of glycol chitosan with a synthesized benzaldehyde terminated polymer gelator, and hydrogels are efficiently obtained in several minutes at room temperature. By varying ratios between glycol chitosan, polymer gelator, and water contents, versatile hydrogels with different gelation times and stiffness are obtained. When damaged, the hydrogel can recover its appearances and modulus, due to the reversibility of the dynamic imine bonds as crosslinkages. This self-healable property enables the hydrogel to be injectable since it can be self-healed from squeezed pieces to an integral bulk hydrogel after the injection process. The hydrogel is also multi-responsive to many bio-active stimuli due to different equilibration statuses of the dynamic imine bonds. This hydrogel was confirmed as bio-compatible, and L929 mouse fibroblast cells were embedded following standard procedures and the cell proliferation was easily assessed by a 3D cell cultivation process. The hydrogel can offer an adjustable platform for different research where a physiological mimic of a 3D environment for cells is profited. Along with its multi-responsive, self-healable, and injectable properties, the hydrogels can potentially be applied as multiple carriers for drugs and cells in future bio-medical applications.

Here we describe a facile preparation of chitosan-based injectable hydrogels using dynamic imine chemistry. Methods to adjust the hydrogel&#8217;s mechanical strength and its application in 3D cell culture are presented.

糖注射水凝胶的制备及其在3D 细胞培养中的应用

The protocol presents a facile, efficient, and versatile method to prepare chitosan-based hydrogels using dynamic imine chemistry. The hydrogel is ...

Determination of Thermodynamic Properties of Alkaline Earth-liquid Metal Alloys Using the Electromotive Force Technique

A novel electrochemical cell based on a CaF2 solid-state electrolyte has been developed to measure the electromotive force (emf) of binary alkaline earth-liquid metal alloys as functions of both composition and temperature in order to acquire thermodynamic data. The cell consists of a chemically stable solid-state CaF2-AF2 electrolyte (where A is the alkaline-earth element such as Ca, Sr, or Ba), with binary A-B alloy (where B is the liquid metal such as Bi or Sb) working electrodes, and a pure A metal reference electrode. Emf data are collected over a temperature range of 723 K to 1,123 K in 25 K increments for multiple alloy compositions per experiment and the results are analyzed to yield activity values, phase transition temperatures, and partial molar entropies/enthalpies for each composition.

This protocol describes the measurement of the electromotive force of alkaline-earth elements in liquid metal alloys at high temperatures (723-1,123 K) to determine their thermodynamic properties, including activity, partial molar entropy, partial molar enthalpy, and phase transition temperatures, over a wide composition range.

用电动势技术测定碱土金属合金的热力学性质

A novel electrochemical cell based on a CaF2 solid-state electrolyte has been developed to measure the electromotive force (emf) of binary alkaline ...

Preparation of Stable Bicyclic Aziridinium Ions and Their Ring-Opening for the Synthesis of Azaheterocycles

Bicyclic aziridinium ions were generated by the removal of an appropriate leaving group through internal nucleophilic attack by nitrogen atom in the aziridine ring. The utility of bicyclic aziridinium ions, specifically 1-azoniabicyclo[3.1.0]hexane and 1-azoniabicyclo[4.1.0]heptane tosylate highlighted in the aziridine ring openings by the nucleophile with the release of the ring strain to yield the corresponding ring-expanded azaheterocycles such as pyrrolidine, piperidine and azepane with diverse substituents on the ring in regio- and stereospecific manner. Herein, we report a simple and convenient method for the preparation of the stable 1-azabicyclo[4.1.0]heptane tosylate followed by selective ring opening via a nucleophilic attack either at the bridge or at the bridgehead carbon to yield piperidine and azepane rings, respectively. This synthetic strategy allowed us to prepare biologically active natural products containing piperidine and azepane motif including sedamine, allosedamine, fagomine and balanol in highly efficient manner.

Bicyclic aziridinium ions such as 1-azoniabicyclo[4.1.0]heptane tosylate were generated from 2-[4-tolenesulfonyloxybutyl]aziridine, which was utilized for the preparation of substituted piperidines and azepanes via regio- and stereospecific ring-expansion with various nucleophiles. This highly efficient protocol allowed us to prepare diverse azaheterocycles including natural products such as fagomine, febrifugine analogue and balanol.

稳定笼 Aziridinium 离子的制备及其开环 Azaheterocycles 的合成

Bicyclic aziridinium ions were generated by the removal of an appropriate leaving group through internal nucleophilic attack by nitrogen atom in the ...

Disentangling High Strength Copolymer Aramid Fibers to Enable the Determination of Their Mechanical Properties

Traditionally, soft body armor has been made from poly(p-phenylene terephthalamide) (PPTA) and ultra-high molecular weight polyethylene. However, to diversify the fiber choices in the United States body armor market, copolymer fibers based on the combination of 5-amino-2-(p-aminophenyl) benzimidazole (PBIA) and the more conventional PPTA were introduced. Little is known regarding the long-term stability of these fibers, but as condensation polymers, they are expected to have potential sensitivity to moisture and humidity. Therefore, characterizing the strength of the materials and understanding their vulnerability to environmental conditions is important for evaluating their use lifetime in safety applications. Ballistic resistance and other critical structural properties of these fibers are predicated on their strength. To accurately determine the strength of the individual fibers, it is necessary to disentangle them from the yarn without introducing any damage. Three aramid-based copolymer fibers were selected for the study. The fibers were washed with acetone followed by methanol to remove an organic coating that held the individual fibers in each yarn bundle together. This coating makes it difficult to separate single fibers from the yarn bundle for mechanical testing without damaging the fibers and affecting their strength. After washing, fourier transform infrared (FTIR) spectroscopy was performed on both washed and unwashed samples and the results were compared. This experiment has shown that there are no significant variations in the spectra of poly(p-phenylene-benzimidazole-terephthalamide-co-p-phenylene terephthalamide) (PBIA-co-PPTA1) and PBIA-co-PPTA3 after washing, and only a small variation in intensity for PBIA. This indicates that the acetone and methanol rinses are not adversely affecting the fibers and causing chemical degradation. Additionally, single fiber tensile testing was performed on the washed fibers to characterize their initial tensile strength and strain to failure, and compare those to other reported values. Iterative procedural development was necessary to find a successful method for performing tensile testing on these fibers.

The primary goal of the study is to develop a protocol to prepare consistent specimens for accurate mechanical testing of high strength copolymer aramid fibers, by removing a coating and disentangling the individual fiber strands without introducing significant chemical or physical degradation.

解析高强共聚物芳纶纤维使其力学性能的测定

Traditionally, soft body armor has been made from poly(p-phenylene terephthalamide) (PPTA) and ultra-high molecular weight polyethylene. However, to ...

Surface Properties of Synthesized Nanoporous Carbon and Silica Matrices

In this work, we report the synthesis and characterization of ordered nanoporous carbon material (also called ordered mesoporous carbon material [OMC]) with a 4.6 nm pore size, and ordered silica porous matrix, SBA-15, with a 5.3 nm pore size. This work describes the surface properties of nanoporous molecular sieves, their wettability, and the melting behavior of D2O confined in the differently ordered porous materials with similar pore sizes. For this purpose, OMC and SBA-15 with highly ordered nanoporous structures are synthesized via impregnation of the silica matrix by applying a carbon precursor and by the sol-gel method, respectively. The porous structure of investigated systems is characterized by an N2 adsorption-desorption analysis at 77 K. To determine the electrochemical character of the surface of synthesized materials, potentiometric titration measurements are conducted; the obtained results for OMC shows a significant pHpzc shift toward the higher values of pH, relative to SBA-15. This suggests that investigated OMC has surface properties related to oxygen-based functional groups. To describe the surface properties of the materials, the contact angles of liquids penetrating the studied porous beds are also determined. The capillary rise method has confirmed the increased wettability of the silica walls relative to the carbon walls and an influence of the pore roughness on the fluid/wall interactions, which is much more pronounced for silica than for carbon mesopores. We have also studied the melting behavior of D2O confined in OMC and SBA-15 by applying the dielectric method. The results show that the depression of the melting temperature of D2O in the pores of OMC is about 15 K higher relative to the depression of the melting temperature in SBA-15 pores with a comparable 5 nm size. This is caused by the influence of adsorbate/adsorbent interactions of the studied matrices.

Here we report the synthesis and characterization of ordered nanoporous carbon (with a 4.6 nm pore size) and SBA-15 (with a 5.3 nm pore size). The work describes the surface and textural properties of nanoporous molecular sieves, their wettability, and the melting behavior of D2O confined in the materials.

合成纳米碳和二氧化硅矩阵的表面性能

In this work, we report the synthesis and characterization of ordered nanoporous carbon material (also called ordered mesoporous carbon material [OMC]) ...