这项工作得到了弗吉尼亚理工学院和州立大学开办资金的支持。Q.F. 承认中国国家自然科学基金 (21504047)、江苏省自然科学基金 (BK20150834)、南京邮电大学科学基金 NUPTSF (NY214179) 的支持。

警告: 使用前请查阅所有相关材料安全数据表 (MSDS)。合成中使用的许多化学物质具有剧毒和致癌性。在执行反应时, 请使用所有适当的安全做法, 包括使用工程控制 (油烟罩和手套) 和个人防护用品 (安全眼镜、手套、实验室大衣、全长长裤、闭脚趾鞋、蓝光屏蔽安全护目镜)。以下程序涉及在手套箱中的标准无处理技术。所有的解决方案都是用吸管转移的。
1. 催化剂和引发剂的制备
注: 整个过程是在一个带有冷阱的手套箱中进行的。所有化学物质在进入盒子前都要经过干燥或纯化。13所有瓶子和玻璃器皿都在烤箱里烘干和加热, 然后再搬进盒子里。
<ol><li>
(bpy) 镍 (COD) 溶液的制备 注: (bpy) Ni (COD) 应在原位就地进行准备。它应存放在手套箱冷冻机 (-35 ° c), 并在一个星期内使用。所有其他催化剂和引发剂的解决方案都可以储存在1月以上的手套箱冰柜中。<ol>
<li>称 Ni (COD)2 (3.5 毫克, 12.7 µmol, 1.0 eq) 变成7毫升的闪烁瓶。</li>
		<li>称 2,2-吡啶 (5.9 毫克, 37.8 µmol) 为7毫升的闪烁小瓶。</li>
		<li>在1毫升无水四氢呋喃 (呋喃) 中溶解 2,2-吡啶。</li>
		<li>将产生的 2,2-吡啶溶液 (337 µL) 添加到含有 Ni (COD)2的小瓶中。</li>
		<li>稀释1毫升无水呋喃的混合物。</li>
		<li>瓶盖的瓶子和地方的反应混合物在室温下2小时。 注: ni (cod)2不可溶于呋喃, 而 (bpy) ni (cod) 可溶于呋喃。2小时后紫色溶液中不应有沉淀。</li>
		<li>将 (bpy) 镍 (COD) 储存在-35 ° c 的冰箱中。</li>
	</ol>
</li>
	<li>
锌 (HMDS)2溶液的制备
	<ol>
<li>添加锌 (HMDS)2 (3.3 毫克, 4 µL, 8.5 µmol) 到7毫升闪烁瓶。</li>
		<li>在1毫升无水呋喃中溶解锌 (HMDS)2 。</li>
		<li>存储锌 (HMDS)2解决方案在-35 ° c 的冰箱。</li>
	</ol>
</li>
	<li>
BnOH 溶液的制备
	<ol>
<li>添加 BnOH (4.0 毫克, 4 µL, 37.0 µmol) 到7毫升闪烁瓶。</li>
		<li>在4毫升无水呋喃中溶解 BnOH。</li>
		<li>在-35 ° c 冰箱中存储 BnOH 溶液。</li>
	</ol>
</li>
	<li>
Ir-1 溶液的制备
	<ol>
<li>关闭手套箱灯。 注意: 在聚合之前, 必须关闭手套盒灯以避免Ir-1的失活。</li>
		<li>将Ir-1 (2.9 毫克, 2.6 µmol) 添加到7毫升闪烁瓶中。</li>
		<li>在3毫升无水呋喃中溶解Ir-1 。</li>
		<li>将Ir-1解决方案存储在-35 ° c 的冰箱中。</li>
	</ol>
</li>
</ol>2. l-1 的 Photoredox 环开聚合
注: 整个过程是在一个带有冷阱的手套箱中进行的。在使用前, 所有的亚奥亚单体都是在手套箱中再结晶。13在这里, 我们给出的例子聚合在 DP=500 ([l -1]/[(bpy) 镍 (COD)]/[锌 (HMDS)2]/[BnOH]/[Ir-1] = 500/1/1/1/0.1)。聚合物在不同的 DPs 也可以通过相应的调整单体质量。
<ol><li>
聚合 l-1 溶液的制备
	<ol>
<li>将 l-1 (72.2 毫克, 375.7 µmol) 添加到7毫升闪烁瓶中。</li>
		<li>在722µL 的无水呋喃中溶解 l-1 。</li>
		<li>将 l-1解决方案中的200µL 添加到另一个 7 mL 闪烁小瓶中, 并装有搅拌棒。</li>
		<li>在7毫升的闪烁瓶中加入100µL 无水呋喃。</li>
		<li>盖上瓶子, 并将 l-1解决方案置于冷阱中。</li>
		<li>关闭手套箱灯。 注意: 在聚合之前, 必须关闭手套盒灯以避免Ir-1的失活。</li>
	</ol>
</li>
	<li>
冷却冷阱
	<ol>
<li>在盒子里, 把温度计放进冰冷的陷阱里。</li>
		<li>在盒子外面, 将约500毫升的乙醇加入杜瓦瓶。</li>
		<li>在杜瓦瓶中加入液氮。</li>
		<li>将团体杜瓦瓶装入冷阱。</li>
		<li>将冷阱冷却到-50 ° c。</li>
		<li>在冷阱下放置一个搅拌板 (参见图 1)。</li>
	</ol>
</li>
	<li>
进行 photoredox 环开聚合 注: 在开始聚合前, 放置安全护目镜, 阻挡蓝光。所有的催化剂系统解决方案立即从冷冻库中取出, 并先后添加到7毫升闪烁瓶包含20毫克的 l-1没有暂停或中断三十年代。<ol>
<li>添加 (bpy) Ni (COD) 溶液 (16.4 µL, 0.208 µmol) 到包含 l-1的 7 mL 闪烁小瓶中 (在2.1 中准备)。</li>
		<li>将锌 (HMDS)2溶液 (24.4 µL、0.208 µmol) 添加到小瓶中。</li>
		<li>将 BnOH 溶液 (22.5 µL, 0.208 µmol) 加入瓶中。</li>
		<li>将 Ir-1 溶液 (24.2 µL, 0.0208 µmol) 放入小瓶中, 然后盖上瓶子。</li>
		<li>戴安全护目镜阻挡蓝色 LED 灯。 注意: 当使用相对高强度的蓝色 LED 灯时, 在整个过程中佩戴安全护目镜。</li>
		<li>打开蓝色 led 灯 (34 W) 和风扇, 以驱散由 led 灯产生的热量。在寒冷的陷阱里把光引向瓶子。(图 1)</li>
		<li>打开搅拌器。</li>
		<li>用铝箔盖住冷阱。</li>
		<li>将反应温度保持在-15 ±5° c, 每15-20 分钟加液氮。 注: 反应温度的维持是聚合和兆瓦控制的重要因素。</li>
	</ol>
</li>
</ol>3. 用傅里叶变换红外光谱监测单体转换
注: 傅立叶变换红外光谱 (FTIR) 记录在红外光谱仪上, 装有金刚石 ATR 和透射采样附件。
<ol><li>在特定时间点, 添加一个小分聚合物溶液 (20 µL) 成一个7毫升的闪烁瓶, 并加盖。</li>
	<li>从手套箱里取出瓶子。</li>
	<li>立即将溶液 (3 µL) 放到 FTIR-ATR 金刚石取样器上。解答在十年代之内形成影片为光谱测量。</li>
	<li>测量样品的 FTIR 光谱。 注: 单体转换是由1760厘米-1和 1805s cm-1的强度比决定的: conversion% = I1760/(I1760 + i1805) (代表结果在图 2)。一般情况下, 从200到1000的 DP 范围, 聚合大约需要 1-8 h (详细的动力学在参考13中讨论)。</li>
</ol>4. 凝胶-渗透色谱法测定聚合物分子量
注: 凝胶渗透色谱 (GPC) 实验是在装有气、多激光光散射 (加工) 探测器 (GaAs 30 mW 激光 at λ = 690 nm) 和差分折射率 (直接还原铁) 探测器的系统上进行的。有 690 nm 的光源使用串行连接的大小排除列 (100 Å、500Å、103 Å和 104 Å列、5µm、300 x 4.6 mm) 在35° c 使用呋喃作为流动相, 以0.35 毫升/分钟的流速执行分色。聚合物分子量 (兆瓦) 和分子量分布 (-) 是用 Zimm 模型拟合的加工-直接还原铁数据确定的.聚合物中金属络合物的存在并不影响 GPC 的测量结果。
<ol><li>从手套箱中取出一小分聚合物溶液 (50 µL)。</li>
	<li>将100µL 的呋喃加入瓶中。</li>
	<li>将样品注入 GPC 取样器。</li>
	<li>在 GPC 运行完成后分析结果。 注: 聚合物应分散与狭窄的Đ (代表结果在图 3)。该聚合物 (20 毫克) 可由1毫升乙醚 (含1% 霍阿克和1毫升甲醇) 进行干燥和洗涤, 可去除87% 的镍和50% 的锌配合物, 由电感耦合等离子体质谱 (ICP) 测定。</li>
</ol>

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作者声明没有竞争的金融利益。本论文提出了一项临时专利 (美国专利申请号:62/414016)。

协议中的关键步骤是保持反应温度在-15 ±5° c。在聚合之前, 所有的催化剂溶液和亚奥基单体都必须在-35 ° c 的手套箱冷冻库中储存。在寒冷的陷阱中, 反应瓶必须预。在反应过程中, 由于 LED 灯散热, 必须每 15-20 分钟监测反应。一旦温度上升到-10 ° c, 液态氮应加入到杜瓦瓶冷却陷阱。低温的原因是室温下镍 (CO) 络合物的形成, 这对受控的 photoredox 聚合是不利的, 并影响到兆瓦和Đ。<sup class="xr...

聚 (α-羟基酸) (PAHA) 是一类重要的生物降解和生物相容性高分子材料, 其应用范围广泛, 从医用设备到包装原料。1,2虽然 PAHAs 可以通过α-羟基酸的缩聚直接制备, 但产生的 PAHAs 的分子量 (MWs) 普遍较低。3酯 (如丙交酯和乙) 的开环聚合 (ROP) 是一种替代合成方法, 可以更好地控制 MWs 和分子量分布 (Đ), 而不是缩聚。然而, PAHAs 和酯的侧链功能的缺乏限制了物理和化学性质及其应用的多样性。4,5自2006年以来, 13--1,3--24-diones, so-called O-carboxyanhydrides (oca), 可以用丰富多样的侧链功能编写,6,7,8,9,10,11,12,13已成为聚酯聚合中一种高活性单体的替代类。14,15
oca 的催化系统可分为有机、8、12、16、17有机金属催化剂12、18、19 ,20,21和催化剂。22一般情况下, 由有机促进的 oca 的 ROP 以或多或少不受控制的方式进行, 例如异构化 (即缺少 stereoregularity), 用于 oca 轴承电子提取组,8,17不可预知的 MWs, 或慢聚合动力学。13为了解决这些问题, 研制了一种活性锌-醇络合物, 用于 oca 的 ROP。12井控保护在低聚合 (DP) 的情况下, 没有异构化。然而, 这种锌-醇催化剂不能有效地产生高聚合度的聚合物 (DP ≥ 300)。13
我们最近报告了一种有希望的方法, 大大提高了 PAHA 合成的可和效率 (图 1)。13将 photoredox 镍/Ir 催化剂与锌醇脱, 以调节环开聚合 oca。低温 (-15 ° c) 和 photoredox 镍/Ir 催化的使用, 协同加速了脱链的传播, 同时避免了不受欢迎的副反应, 如镍羰基的形成。23,24在转移与 Ni 复合体的活性锌-醇位于链终点链传播。13
在本协议中, 我们添加新鲜准备 (bpy) Ni (COD) (bpy = 22 '-吡啶, COD = 15-1,5-), Zn (HMDS)2 (HMDS = 烷),25苄醇 (BnOH) 和 Ir [dF (CF3) 吡]2(dtbbpy) PF6 (Ir-1, dF (CF3) 吡 = 2-(24-氟)-5-三氟甲基吡啶, dtbbpy = 44 "-di-叔-butyl-2,2'-bipyridine) 到单体 l-1解决方案26在一个带有冷陷阱的手套箱中, 在一个蓝色 LED 灯 (400-500 nm) 和风扇以保持温度 (图 1)。在聚合过程中, 温度保持在-15 ° c ±5° c。采用傅里叶变换红外光谱法对亚奥氏转化率进行了监测。由此产生的聚合物 MWs 和Đs 的特点是凝胶渗透色谱 (GPC)。homodecoupling 的1H 核磁共振研究确定所得到的聚合物是否是规的。由于大多数化学品对湿气高度敏感, 详细的视频协议旨在帮助新的从业者避免与 oca photoredox ROP 相关的陷阱。

<table>
	<tbody>
		<tr>
			<td>Ni(COD)2</td>
			<td>Strem</td>
			<td>28-0010</td>
			<td>Stored in the glove box freezer.</td>
		</tr>
		<tr>
			<td>2,2&#8242;-bipyridine</td>
			<td>Strem</td>
			<td>07-0290</td>
			<td>Stored in the glove box freezer.</td>
		</tr>
		<tr>
			<td>Zn(HMDS)2</td>
			<td>N/A</td>
			<td>N/A</td>
			<td>Synthesized following reported procedures.25 Stored in the glove box freezer.</td>
		</tr>
		<tr>
			<td>Benzyl alcohol</td>
			<td>Sigma-Aldrich</td>
			<td>402834</td>
			<td>Stored with 4&#197; molecular sieve</td>
		</tr>
		<tr>
			<td>Ir[dF(CF3)ppy]2(dtbbpy)PF6</td>
			<td>Strem</td>
			<td>77-0425</td>
			<td>Stored in the glove box freezer.</td>
		</tr>
		<tr>
			<td>THF</td>
			<td>Sigma-Aldrich</td>
			<td>34865</td>
			<td>Dried by alumina columns and stored with 4&#197; molecular sieve in the dark bottle in the glove box.</td>
		</tr>
		<tr>
			<td>Ethanol</td>
			<td>Sigma-Aldrich</td>
			<td>793175</td>
			<td></td>
		</tr>
		<tr>
			<td>GPC with an isocratic pump</td>
			<td>Agilent</td>
			<td>Agilent 1260 series</td>
			<td></td>
		</tr>
		<tr>
			<td>Dawn Heleos II Light Scatterer</td>
			<td>Wyatt</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Optilab rEX differential refractive index detector</td>
			<td>Wyatt</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Size exclusion columns</td>
			<td>Phenomenex</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Glass Scintillation Vials - 7 ml</td>
			<td>VWR</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>FTIR spectrometer</td>
			<td>Agilent</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Stir bars</td>
			<td>VWR</td>
			<td>58948-091</td>
			<td></td>
		</tr>
		<tr>
			<td>Balance</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Glove box</td>
			<td>Mbraun</td>
			<td>Labstar Pro</td>
			<td></td>
		</tr>
	</tbody>
</table>

controlled photoredox ring-opening polymerization of o-carboxyanhydrides mediated by ni/zn complexes

在这里, 我们描述一个有效的协议, 结合 photoredox 镍/Ir 催化与使用锌醇的有效开环聚合, 允许合成的规聚 (α-羟基酸) 与预期的分子量 (> 140kDa) 和窄分子量分布 (Mw/mn < 1.1)。这种环开聚合由 Ni 和锌配合物在乙醇引发剂和 photoredox 红外催化剂的存在下进行介导, 由蓝色 LED (400-500 nm) 照射。在低温 (-15 ° c) 下进行聚合以避免不受欢迎的副反应。完整的单体消耗可以在 4-8 小时内完成, 为聚合物提供接近分子量的分子量分布。结果数字平均分子量显示一个线性相关与聚合程度1000。homodecoupling 的1H 核磁共振研究证实, 所获得的聚合物是规没有异构化。本文所报告的聚合提供了一种实现快速、受控的O-carboxyanhydrides 聚合的策略, 以制备 stereoregular 聚 (α-羟基酸) 及其承载各种功能侧链基团的共聚物。

通过傅里叶变换红外光谱对亚奥的转换进行监测, 如图 2所示。在 1805 cm-1的峰值被分配为在亚奥理事会中的酸酐粘结拉伸;峰值在 1760 cm-1对应于聚合物中酯键的形成。一旦单体的峰值在1805厘米-1完全消失, 聚合完成。
所产生的聚合物的兆瓦和Đ以凝胶渗透色谱为特征。<strong c...

Watch this Scientific Journal Video about Controlled Photoredox Ring-Opening Polymerization of O-Carboxyanhydrides Mediated by Ni/Zn Complexes at JoVE.com

Controlled Photoredox Ring-Opening Polymerization of O-Carboxyanhydrides Mediated by Ni/Zn Complexes

介绍了由 Ni/锌配合物介导的受控 photoredox 环开放聚合的O-carboxyanhydrides 的协议。

镍/锌配合物介导的O-Carboxyanhydrides 的控制 Photoredox 环开聚合

Here, we describe an effective protocol that combines photoredox Ni/Ir catalysis with the use of a Zn-alkoxide for efficient ring-opening polymerization, ...

controlled-photoredox-ring-opening-polymerization-o-carboxyanhydrides

Research

JoVE Journal

Chemistry

Controlled Photoredox Ring-Opening Polymerization of O-Carboxyanhydrides Mediated by Ni/Zn Complexes

8.0K 次观看.  Nanjing University of Posts and Telecommunications. 介绍了由 Ni/锌配合物介导的受控 photoredox 环开放聚合的O-carboxyanhydrides 的协议。

视频: Controlled Photoredox Ring-Opening Polymerization of O-Carboxyanhydrides Mediated by Ni/Zn Complexes

Production of Disulfide-stabilized Transmembrane Peptide Complexes for Structural Studies

Physical interactions among the lipid-embedded alpha-helical domains of membrane proteins play a crucial role in folding and assembly of membrane protein complexes and in dynamic processes such as transmembrane (TM) signaling and regulation of cell-surface protein levels. Understanding the structural features driving the association of particular sequences requires sophisticated biophysical and biochemical analyses of TM peptide complexes. However, the extreme hydrophobicity of TM domains makes them very difficult to manipulate using standard peptide chemistry techniques, and production of suitable study material often proves prohibitively challenging. Identifying conditions under which peptides can adopt stable helical conformations and form complexes spontaneously adds a further level of difficulty. Here we present a procedure for the production of homo- or hetero-dimeric TM peptide complexes from materials that are expressed in E. coli, thus allowing incorporation of stable isotope labels for nuclear magnetic resonance (NMR) or non-natural amino acids for other applications relatively inexpensively. The key innovation in this method is that TM complexes are produced and purified as covalently associated (disulfide-crosslinked) assemblies that can form stable, stoichiometric and homogeneous structures when reconstituted into detergent, lipid or other membrane-mimetic materials. We also present carefully optimized procedures for expression and purification that are equally applicable whether producing single TM domains or crosslinked complexes and provide advice for adapting these methods to new TM sequences.

Biophysical and biochemical studies of interactions among membrane-embedded protein domains face many technical challenges, the first of which is obtaining appropriate study material. This article describes a protocol for producing and purifying disulfide-stabilized transmembrane peptide complexes that are suitable for structural analysis by solution nuclear magnetic resonance (NMR) and other analytical applications.

生产二硫键稳定的跨膜肽复合物的结构研究

Physical  interactions among the lipid-embedded alpha-helical domains of membrane  proteins play a crucial role in folding and assembly of membrane ...

科研

化学

Anticancer Metal Complexes: Synthesis and Cytotoxicity Evaluation by the MTT Assay

Titanium (IV) and vanadium (V) complexes are highly potent anticancer agents. A challenge in their synthesis refers to their hydrolytic instability; therefore their preparation should be conducted under an inert atmosphere. Evaluation of the anticancer activity of these complexes can be achieved by the MTT assay.
The MTT assay is a colorimetric viability assay based on enzymatic reduction of the MTT molecule to formazan when it is exposed to viable cells. The outcome of the reduction is a color change of the MTT molecule. Absorbance measurements relative to a control determine the percentage of remaining viable cancer cells following their treatment with varying concentrations of a tested compound, which is translated to the compound anticancer activity and its IC50 values. The MTT assay is widely common in cytotoxicity studies due to its accuracy, rapidity, and relative simplicity.
Herein we present a detailed protocol for the synthesis of air sensitive metal based drugs and cell viability measurements, including preparation of the cell plates, incubation of the compounds with the cells, viability measurements using the MTT assay, and determination of IC50 values.

A method for synthesis of air-sensitive titanium and vanadium anticancer agents is described, along with the evaluation of their cytotoxic activity towards human cancer cell line by the MTT Assay.

抗癌金属配合物的合成与细胞毒性评价MTT法

Titanium (IV) and vanadium (V) complexes are highly potent anticancer agents. A challenge in their synthesis refers to their hydrolytic instability; ...

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 ...

Ethylene Polymerizations Using Parallel Pressure Reactors and a Kinetic Analysis of Chain Transfer Polymerization

We demonstrate a method for high-throughput catalyst screening using a parallel pressure reactor starting from the initial synthesis of a nickel &#945;-diimine ethylene polymerization catalyst. Initial polymerizations with the catalyst lead to optimized reaction conditions, including catalyst concentration, ethylene pressure and reaction time. Using gas-uptake data for these reactions, a procedure to calculate the initial rate of propagation (kp) is presented. Using the optimized conditions, the ability of the nickel &#945;-diimine polymerization catalyst to undergo chain transfer with diethylzinc (ZnEt2) during ethylene polymerization was investigated. A procedure to assess the ability of the catalyst to undergo chain transfer (from molecular weight and 13C NMR data), calculate the degree of chain transfer, and calculate chain transfer rates (ke) is presented.

A protocol for the high-throughput analysis of polymerization catalyst, chain transfer polymerizations, polyethylene characterization, and reaction kinetic analysis is presented.

乙烯聚合中使用并联电抗器的压力和链转移聚合的动力学分析

We demonstrate a method for high-throughput catalyst screening using a parallel pressure reactor starting from the initial synthesis of a nickel ...

Atom Transfer Radical Polymerization of Functionalized Vinyl Monomers Using Perylene as a Visible Light Photocatalyst

A standardized technique for atom transfer radical polymerization of vinyl monomers using perylene as a visible-light photocatalyst is presented. The procedure is performed under an inert atmosphere using air- and water-exclusion techniques. The outcome of the polymerization is affected by the ratios of monomer, initiator, and catalyst used as well as the reaction concentration, solvent, and nature of the light source. Temporal control over the polymerization can be exercised by turning the visible light source off and on. Low dispersities of the resultant polymers as well as the ability to chain-extend to form block copolymers suggest control over the polymerization, while chain end-group analysis provides evidence supporting an atom-transfer radical polymerization mechanism.

A method for the atom transfer radical polymerization of functionalized vinyl monomers using perylene as a visible-light photocatalyst is described.

使用苝作为可见光光催化功能化的乙烯基单体原子转移自由基聚合

A standardized technique for atom transfer radical polymerization of vinyl monomers using perylene as a visible-light photocatalyst is presented. The ...

Facile Synthesis of Worm-like Micelles by Visible Light Mediated Dispersion Polymerization Using Photoredox Catalyst

Presented herein is a protocol for the facile synthesis of worm-like micelles by visible light mediated dispersion polymerization. This approach begins with the synthesis of a hydrophilic poly(oligo(ethylene glycol) methyl ether methacrylate) (POEGMA) homopolymer using reversible addition-fragmentation chain-transfer (RAFT) polymerization. Under mild visible light irradiation (&#955; = 460 nm, 0.7 mW/cm2), this macro-chain transfer agent (macro-CTA) in the presence of a ruthenium based photoredox catalyst, Ru(bpy)3Cl2 can be chain extended with a second monomer to form a well-defined block copolymer in a process known as Photoinduced Electron Transfer RAFT (PET-RAFT). When PET-RAFT is used to chain extend POEGMA with benzyl methacrylate (BzMA) in ethanol (EtOH), polymeric nanoparticles with different morphologies are formed in situ according to a polymerization-induced self-assembly (PISA) mechanism. Self-assembly into nanoparticles presenting POEGMA chains at the corona and poly(benzyl methacrylate) (PBzMA) chains in the core occurs in situ due to the growing insolubility of the PBzMA block in ethanol. Interestingly, the formation of highly pure worm-like micelles can be readily monitored by observing the onset of a highly viscous gel in situ due to nanoparticle entanglements occurring during the polymerization. This process thereby allows for a more reproducible synthesis of worm-like micelles simply by monitoring the solution viscosity during the course of the polymerization. In addition, the light stimulus can be intermittently applied in an ON/OFF manner demonstrating temporal control over the nanoparticle morphology.

This article describes a process for producing polymeric self-assembled nanoparticles using visible light mediated dispersion polymerization. Using low energy visible light to control the polymerization allows for the reproducible formation of self-assembled worm-like micelles at high solids content.

使用Photoredox催化剂蠕虫状胶束的简便合成可见光介导的分散聚合

Presented herein is a protocol for the facile synthesis of worm-like micelles by visible light mediated dispersion polymerization. This approach begins ...

Anionic Polymerization of an Amphiphilic Copolymer for Preparation of Block Copolymer Micelles Stabilized by &#960;-&#960; Stacking Interactions

In this study, an amphiphilic copolymer that includes a core-forming block with phenyl groups was synthesized by living anionic polymerization of phenyl glycidyl ether (PheGE) on methoxy-polyethylene glycol (mPEG-b-PPheGE). Characterization of the copolymer revealed a narrow molecular distribution (PDI &#60; 1.03) and confirmed the degree of polymerization of mPEG122-b-(PheGE)15. The critical micelle concentration of the copolymer was evaluated using an established fluorescence method with the aggregation behavior evaluated by dynamic light scattering and transmission electronic microscopy. The potential of the copolymer for use in drug delivery applications was evaluated in a preliminary manner including in vitro biocompatibility, loading and release of the hydrophobic anti-cancer drug doxorubicin (DOX). A stable micelle formulation of DOX was prepared with drug loading levels up to 14% (wt%), drug loading efficiencies &#62; 60% (w/w) and sustained release of drug over 4 days under physiologically relevant conditions (acidic and neutral pH, presence of albumin). The high drug loading level and sustained release is attributed to stabilizing &#960;-&#960; interactions between DOX and the core-forming block of the micelles.

The key steps of living anionic polymerization of phenyl glycidyl ether (PheGE) on methoxy-polyethylene glycol (mPEG-b-PPheGE) are described. The resulting block copolymer micelles (BCMs) were loaded with doxorubicin 14% (wt%) and sustained release of drug over 4 days under physiologically relevant conditions was obtained.

一个两亲性共聚物的阴离子聚合通过π-π堆积作用稳定嵌段共聚物胶束的制备

In this study, an amphiphilic copolymer that includes a core-forming block with phenyl groups was synthesized by living anionic polymerization of phenyl ...

A Simple and Efficient Protocol for the Catalytic Insertion Polymerization of Functional Norbornenes

Norbornene can be polymerized by a variety of mechanisms, including insertion polymerization whereby the double bond is polymerized and the bicyclic nature of the monomer is conserved. The resulting polymer, polynorbornene, has a very high glass transition temperature, Tg, and interesting optical and electrical properties. However, the polymerization of functional norbornenes by this mechanism is complicated by the fact that the endo substituted norbornene monomer has, in general, a very low reactivity. Furthermore, the separation of the endo substituted monomer from the exo monomer is a tedious task. Here, we present a simple protocol for the polymerization of substituted norbornenes (endo:exo ca. 80:20) bearing either a carboxylic acid or a pendant double bond. The process does not require that both isomers be separated, and proceeds with low catalyst loadings (0.01 to 0.02 mol%). The polymer bearing pendant double bonds can be further transformed in high yield, to afford a polymer bearing pendant epoxy groups. These simple procedures can be applied to prepare polynorbornenes with a variety of functional groups, such as esters, alcohols, imides, double bonds, carboxylic acids, bromo-alkyls, aldehydes and anhydrides.

We describe the catalytic insertion polymerization of 5-norbornene-2-carboxylic acid and 5-vinyl-2-norbornene to form functional polymers with a very high glass transition temperature.

功能性降冰片烯的催化聚合插入一种简单高效的协议

Norbornene can be polymerized by a variety of mechanisms, including insertion polymerization whereby the double bond is polymerized and the bicyclic ...

Extraction of Ramie Fiber in Alkali Hydrogen Peroxide System Supported by Controlled-release Alkali Source

This protocol demonstrates a method for ramie fiber extraction by scouring raw ramie in an alkali hydrogen peroxide system supported by a controlled-release alkali source. The fiber extracted from ramie is a type of textile material of great importance. In previous studies, ramie fiber was extracted in an alkali hydrogen peroxide system supported only by sodium hydroxide.However, due to the strong alkalinity of sodium hydroxide, the oxidation reaction speed of hydrogen peroxide was difficult to control and thus resulted in great damage to the treated fiber. In this protocol, a controlled-release alkali source, which is composed of sodium hydroxide and magnesium hydroxide, is used to provide an alkali condition and buffer the pH value of the alkali hydrogen peroxidesystem. The substitution rate of magnesium hydroxide can adjust the pH value of the hydrogen peroxide system and has great influence on the fiber properties. The pH value and oxidation-reduction potential (ORP) value, which represents the oxidation ability of alkali hydrogen peroxide system, were monitored using a pH meter and ORP meter, respectively. The residual hydrogen peroxide content in the alkali hydrogen peroxide system during the extraction process and the chemical oxygen demand (COD) value of wastewater after fiber extraction are tested by KMnO4 titration method. The yield of fiber is measured using a precision electronic balance, and residual gums of fiber are tested by a chemical analysis method. The polymerization degree (PD value) of fiber is tested by an intrinsic viscosity method using the Ubbelohde viscometer. The tensile property of fiber, including tenacity, elongation, and rupture, is measured using a fiber strength instrument. Fourier transform infrared spectroscopy and X-ray diffraction are used to characterize the functional groups and crystal property of fiber. This protocol proves that the controlled-release alkali source can improve the properties of the fiber extracted in an alkali hydrogen peroxide system.

Presented here is a protocol for extraction of ramie fiber in alkali hydrogen peroxide system supported by controlled-release alkali source.

缓释碱源负载碱性过氧化氢体系中苎麻纤维的提取

This protocol demonstrates a method for ramie fiber extraction by scouring raw ramie in an alkali hydrogen peroxide system supported by a ...

Preparation of Hollow Polystyrene Particles and Microcapsules by Radical Polymerization of Janus Droplets Consisting of Hydrocarbon and Fluorocarbon Oils

In this article, we have demonstrated a method for producing hollow particles and microcapsules using oil droplets consisting of hydrocarbon oil (styrene) and fluorocarbon oil (perfluoro-n-octane, PFO) in aqueous surfactant (sodium dodecylsulfate, SDS) solutions. Since fluorocarbon oils are immiscible with hydrocarbon oils, the two oils are separated. Emulsions are prepared by stirring styrene/PFO/aqueous SDS solution mixtures at 80 &#176;C. The type of emulsions and the morphology of droplets in the emulsions are observed by light microscope and scanning confocal fluorescence microscope. It is found that oil droplets with Janus-type morphologies consisting of mutually immiscible styrene and PFO are formed in aqueous SDS solutions. Polystyrene particles are fabricated by radical polymerization of the ternary mixtures of styrene/PFO/aqueous SDS solution at 80 &#176;C. The morphologies of the polystyrene are confirmed by scanning electron microscopy and scanning transmission electron microscopy observations. These observations show the preparation of hollow polystyrene particles with a single hole on the surface. To our knowledge, this method is a novel strategy using the immiscibility of hydrocarbon and fluorocarbon oils. The hollow particles can also be applied to the preparation of microcapsules.

A protocol for the fabrication of hollow polymer particles and microcapsules by radical polymerization using emulsions consisting of styrene, perfluoro-n-octane, and aqueous SDS (sodium dodecylsulfate) solution is presented.

由烃类和氟碳油组成的同液滴的自由基聚合制备空心聚苯乙烯颗粒和微胶囊

In this article, we have demonstrated a method for producing hollow particles and microcapsules using oil droplets consisting of hydrocarbon oil (styrene) ...