一种具备巯基点击化学功能的二硫代酯RAFT链转移剂的合成

以2,2-二硫二吡啶,2-巯基乙醇为原料,醋酸为催化剂,合成了2-羟乙基-二硫吡啶(PⅠ)。以PⅠ、4-氰基-4-(硫代苯甲酰)戊酸(PⅡ)为原料,1-(3-二甲氨基丙基)-3-乙基碳二亚胺盐酸盐(EDC)、4-二甲氨基吡啶(DMAP)为催化剂,合成了一种新的可逆加成-断裂链转移自由基聚合(RAFT)链转移剂4-氰基-4-(硫代苯甲酰)戊酸-2-二硫吡啶乙酯(PⅢ)。以PⅢ为RAFT链转移剂,偶氮二异丁腈(AIBN)为引发剂,甲基丙烯酸甲酯(MMA)为单体,采用RAFT制备了聚甲基丙烯酸甲酯(PMMA)。用1 H-NMR分析了链转移剂的的分子结构,用GPC测得PMMA聚合物的分子量及其分布。结果表明:能用于巯基点击化学的二硫吡啶基团被接到PⅡ的末端,成功制备了一种具备巯基点击化学功能的二硫代酯RAFT链转移剂(PⅢ),利用PⅢ,通过RAFT聚合制备了分子量分布狭窄的PMMA聚合物。     

RAFT聚合法合成甲基丙烯酸酯共聚物及其在负性光致抗蚀剂中的应用

以甲基丙烯酸(MAA)、甲基丙烯酸苄基酯(BZMA)、甲基丙烯酸羟乙酯(HEMA)和丙烯酸正丁酯(BA)为共聚单体,偶氮二异丁腈(AIBN)为引发剂,2-(十二烷基三硫代碳酸酯基)-2-甲基丙酸(DMP)为链转移试剂,采用可逆加成-断裂链转移聚合(RAFT)制备了甲基丙烯酸酯共聚物(PMBBH)。利用傅立叶红外光谱(FT-IR)、核磁共振氢谱(¹HNMR)和凝胶渗透色谱(GPC)对共聚物的结构进行了表征。以共聚物PMBBH为基体树脂制备了负性光致抗蚀剂,考察了PMBBH的分子量对光致抗蚀剂分辨率的影响。结果表明,以数均分子量为5.45×10³ g/mol,重均分子量为7.79×10³ g/mol的PMBBH-2作为基体树脂时,该光致抗蚀剂得到的图像轮廓清晰,图形分辨率可达50 μm。     

用多官能链转移剂通过普通自由基聚合制备两亲性杂臂星形聚合物

以偶氮二异丁腈为引发剂,四(3-巯基丙酸季戊四醇四酯)(PETMP)为链转移剂进行甲基丙烯酸甲酯(MMA)的自由基聚合,得到了含有残余巯基的聚甲基丙烯酸甲酯大分子链转移剂(HS-PMMA).然后,以HS-PMMA作为大分子链转移剂进行甲基丙烯酸叔丁酯(tBMA)的自由基聚合,合成了杂臂星形聚合物.最后,将所得杂臂星形聚合物的PtBMA链段水解得到了两亲性杂臂星形聚合物.     

医用生物相容性接枝共聚物负载阿霉素和香豆素的研究

以一端连有单电子转移自由基聚合(RAFT)链转移剂的聚乙二醇(PEG)为大分子链转移剂,调控2-(4-羟基丁酰氧基)甲基丙烯酸叔丁酯(t BHBMA)的RAFT聚合,得到的PEG-b-Pt BHBMA嵌段共聚物引发丙交酯的开环聚合,制得接枝共聚物PEG-b-(Pt BA-g-PLA).通过聚乳酸末端的羟基与7-甲氧基香豆素-3-羧酸(COU)中羧基的酯化反应,得到了含有荧光标记分子的接枝共聚物PEG-b-(Pt BA-g-PLA-COU).该聚合物主链选择性水解,得到了含有荧光标记分子的两亲性接枝共聚物PEG-b-(PAA-g-PLA-COU).以PEG-b-(PAA-g-PLA-COU)为药物载体,对阿霉素(DOX)进行了负载,制得了含有荧光标记分子的聚合物载药胶束.利用紫外光谱和动态光散射测定了载药胶束的载药量和胶束尺寸.     

聚[2-(4-苯基偶氮苯氧基)乙基丙烯酸酯]的合成及光响应性能研究

从4-羟基偶氮苯出发,依次与2-氯乙醇、丙烯酰氯反应,合成了2-(4-苯基偶氮苯氧基)乙基丙烯酸酯(PAPEA)。接着以PAPEA为单体,二硫代苯甲酸异丁腈酯(CPDB)为链转移剂,偶氮二异丁腈(AIBN)为引发剂,利用可逆加成-断裂链转移(RAFT)聚合法合成了聚[2-(4-苯基偶氮苯氧基)乙基丙烯酸酯](PPAPEA)均聚物,同时考察了反应时间、引发剂和链转移剂浓度等因素对聚合反应的影响。利用FT-IR、1H-NMR和GPC等对单体和聚合物的结构进行了表征,并利用UV对聚合物的光响应性能进行了测试。结果表明,PAPEA的聚合反应动力学曲线呈良好的线性关系,分子量分布较窄(小于1.3);均聚物在紫外光照下的异构化速率随分子量的增大而减缓,而其在自然光下的回复速率变化不大。     

在选择性溶剂中进行RAFT聚合一步合成核交联的纳米胶束

在选择性溶剂中,大分子RAFT试剂PSSC(S)Ph和AIBN引发剂存在下,进行4乙烯基吡啶(4VP)和二乙烯基苯(DVB)的RAFT聚合,一步合成了稳定的平头型胶束.大分子RAFT试剂是通过以二硫代苯甲酸2(乙氧甲酰基)2丙酯为链转移剂,AIBN为引发剂进行苯乙烯的RAFT聚合反应获得的.嵌段共聚,胶束化和交联反应一锅完成.1HNMR,DLLS,SLLS,TEM和AFM等验证了产品的组成与结构.     

RAFT聚合制备氟硅嵌段共聚物及结构性能

以三硫代酯封端的聚二甲基硅氧烷作为大分子链转移剂,通过可逆加成-断裂链转移聚合(RAFT)制备了一系列聚二甲基硅氧烷-b-聚甲基丙烯酸十二氟庚酯(PDMS-b-PDFHMA)二嵌段共聚物.利用凝胶渗透色谱(GPC)、傅里叶变换红外光谱(FT-IR)、氢核磁共振谱(1H-NMR)对该嵌段共聚物的组成、结构和分子量进行了表...     

通过RAFT自由基聚合合成含叠氮端基的聚N-异丙基丙烯酰胺

S-十二烷基-S′-(2-羧基-异丙基)三硫羧酸酯与叠氮乙醇反应合成了一种新型叠氮链转移剂(2);在2存在下通过可逆加成-断裂链转移(RAFT)自由基聚合合成了含叠氮端基的聚N-异丙基丙烯酰胺(3).其结构经1H NMR, IR和GPC表征.研究结果表明,3呈现较好的温敏性,低临界溶液温度为28.5 ℃.     

含氟丙烯酸酯与苯乙烯共聚物的RAFT合成及表征

通过可逆加成-断链链转移(RAFT)溶液聚合,以三硫代碳酸酯为RAFT试剂,偶氮二异丁腈(AIBN)为引发剂,1,4-二氧六环为溶剂,制备甲基丙烯酸(2,2,2-三氟)乙酯(TFEMA)和苯乙烯(St)共聚物.详细研究了不同引发剂的用量、RAFT试剂与引发剂摩尔比以及聚合温度等实验条件对聚合反应过程的影响.通过GPC、FTIR测试共聚物的分子量、分子量分布和分子结构,并用静态接触角仪和AFM分别表征聚合物膜的接触角、表面能及膜的表面形貌.     

可还原降解梳形阳离子聚合物的合成

通过缩合聚合和可逆加成-断裂链转移聚合(RAFT)合成了一种新型可还原降解的梳形聚阳离子.首先,以具有化学选择性的三氟甲磺酸钪催化苹果酸、二硫二丙酸、癸二醇的三元缩合聚合得到了含多个侧羟基的聚(苹果酸-co-二硫二丙酸)癸二酯;将羟基酯化修饰为双硫酯后,通过甲基丙烯酸二甲氨基乙酯(DMAEMA)的RAFT聚合制备了梳型聚甲基丙烯酸二甲氨基乙酯(PDMAEMA).采用1H-NMR和GPC等测试方法对该聚合物进行结构表征.该梳形阳离子聚合物在还原性环境中可通过双硫键的断裂降解成为小分子量PDMAEMA低聚物.     

Reversible addition–fragmentation chain transfer mediated radical polymerization of asymmetrical divinyl monomers targeting hyperbranched vinyl polymers

Reversible addition–fragmentation chain transfer (RAFT) mediated radical polymerizations of allyl methacrylate and undecenyl methacrylate, compounds containing two types of vinyl groups with different reactivities, were investigated to provide hyperbranched polymers. The RAFT agent benzyl dithiobenzoate was demonstrated to be an appropriate chain‐transfer agent to inhibit crosslinking and obtain polymers with moderate‐to‐high conversions. The polymerization of allyl methacrylate led to a polymer without branches but with five‐ or six‐membered rings. However, poly(undecenyl methacrylate) showed an indication of branching rather than intramolecular cycles. The hyperbranched structure of poly(undecenyl methacrylate) was confirmed by a combination of ¹H, ¹³C, ¹H–¹H correlation spectroscopy, and distortionless enhancement by polarization transfer 135 NMR spectra. The branching topology of the polymers was controlled by the variation of the reaction temperature, chain‐transfer‐agent concentration, and monomer conversion. The significantly lower inherent viscosities of the resulting polymers, compared with those of linear analogues, demonstrated their compact structure. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 26–40, 2007     

Reversible Addition-Fragmentation Chain Transfer Polymerization of Methyl Methacrylate in Microemulsion: The Influence of Reaction Conditions on Polymerization

The reversible addition-fragmentation chain transfer (RAFT) polymerization of methyl methacrylate (MMA) using cetyltrimethylammonium bromide (CTAB) as surfactant and a difunctional RAFT agent S,S′-bis (α, α′-dimethylacetic acid) trithiocarbonate (BDAT) as chain transfer were conducted in microemulsion. The influence of polymerization temperature and concentration of RAFT agent on the polymerization were investigated, respectively. The results showed that the molecular weight of products increased linearly with conversion, the polydispersity indexes remained low value, and the polymerization processes were totally under control with increasing concentration of RAFT agent, the polymerization behavior exhibited living polymerization characters. In addition, the influence of RAFT concentration on the particle size was investigated by TEM. The results indicated that the particles were highly monodispersed and the particle size increased with increasing concentration of RAFT agent.     

SET‐RAFT of MMA mediated by ascorbic acid‐activated copper oxide

In this work, cupric oxide (CuO) or cuprous oxide (Cu₂O) was used as the catalyst for the single electron transfer‐reversible addition‐fragmentation chain transfer (SET‐RAFT) polymerization of methyl methacrylate in the presence of ascorbic acid at 25 °C. 2‐Cyanoprop‐2‐yl‐1‐dithionaphthalate (CPDN) was used as the RAFT agent. The polymerization occurred smoothly after an induction period arising from the slow activation of CuO (or Cu₂O) and the “initialization” process in RAFT polymerization. The polymerizations conveyed features of “living”/controlled radical polymerizations: linear evolution of number‐average molecular weight with monomer conversion, narrow molecular weight distribution, and high retention of chain end fidelity. From the polymerization profile, it was deduced that the polymerization proceeded via a conjunct mechanism of single electron transfer‐living radical polymerization (SET‐LRP) and RAFT polymerization, wherein CPDN acting as the initiator for SET‐LRP and chain transfer agent for RAFT polymerization. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Synthesis of methacrylate derivatives oligomers by dithiobenzoate‐RAFT‐mediated polymerization

Reversible addition fragmentation chain transfer (RAFT) was used to synthesize methacrylic acid oligomers and oligo(methacrylic acid)‐b‐poly(methyl methacrylate) (PMAA‐b‐PMMA) with targeted degree of polymerization ≈ 10. Characterization is by size‐exclusion chromatography (SEC) and electrospray mass‐spectrometry. SEC data are presented as hydrodynamic volume distributions (HVDs), the only proper means to present comparative and meaningful SEC data when there is no unique relationship between size and molecular weight. The RAFT agent, (4‐cyanopentanoic acid)‐4‐dithiobenzoate (CPADB), produced dithiobenzoic acid as a side product during the polymerization of methacrylate derivatives. Precipitation in diethyl ether proved to be an easy way to remove this impurity from the PMAA‐RAFT oligomers. Both unpurified and purified macro‐RAFT agent were used to prepare amphiphilic PMAA‐b‐PMMA copolymers. Diblock copolymer prepared from the purified PMAA homopolymer had a narrower HVD in comparison to those obtained from the equivalent unpurified macro‐RAFT agent. This work shows that while cyanoisopropyl‐dithiobenzoate or CPADB are good RAFT agents for methacrylate derivatives, they exhibit some instability under typical polymerization conditions, and thus when oligomers are targeted, optimal control requires checking for the degradation product and appropriate purification steps when necessary (the same effect is present for larger polymers but is unimportant). © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 2277–2289, 2008     

Living free‐radical polymerization (reversible addition–fragmentation chain transfer) of 6‐[4‐(4′‐methoxyphenyl)phenoxy]hexyl methacrylate: A route to architectural control of side‐chain liquid‐crystalline polymers

Side‐chain liquid‐crystalline polymers of 6‐[4‐(4′‐methoxyphenyl)phenoxy]hexyl methacrylate with controlled molecular weights and narrow polydispersities were prepared via reversible addition–fragmentation chain transfer (RAFT) polymerization with 2‐(2‐cyanopropyl) dithiobenzoate as the RAFT agent. Differential scanning calorimetry studies showed that the polymers produced via the RAFT process had a narrower thermal stability range of the liquid‐crystalline mesophase than the polymers formed via conventional free‐radical polymerization. In addition, a chain length dependence of this stability range was found. The generated RAFT polymers displayed optical textures similar to those of polymers produced via conventional free‐radical polymerization. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2949–2963, 2003     

Reversible Addition‐fragmentation Chain Transfer Polymerization Grafted from Silicon Surface to Prepare Poly(methyl methacrylate) Brushes

通过共价键锚固链转移剂4-氰基-4-二硫代苯甲酰基戊酸琥珀酯于硅片表面,然后采用可逆加成-断裂链转移（RAFT）自由基聚合方法制备了聚甲基丙烯酸甲酯（PMMA）高分子刷. 聚合动力学研究表明,在反应进行2小时后,PMMA的厚度随聚合时间的增大而几乎呈线性增大,具有明显的活性聚合特征. 用椭圆偏光仪、X-光电子能谱（XPS）、原子力显微镜（AFM）及接触角测试对硅片表面的PMMA高分子刷进行了表征.     

Synthesis of block and graft copolymers of styrene by raft polymerization,using dodecyl‐based trithiocarbonates as initiators and chain transfer agents

A series of dodecyl‐based monofunctional trithiocarbonate chain transfer agents (CTAs) were successfully synthesized, toward the reversible addition‐fragmentations chain transfer (RAFT) polymerization of styrene. The CTAs were used as initiators for RAFT polymerization, in the absence of the conventional free radical initiator, at higher temperature. Polystyrene (PS) of narrow polydispersity index (PDI) is synthesized. Subsequently, poly(styrene‐b‐benzyl methacrylate) diblock and poly(styrene‐b‐benzyl methacrylate‐b‐2‐vinyl pyridine) triblock copolymers were synthesized from the PS macro‐RAFT agent by simply heating with the second and third monomer, respectively. These experiments suggest that it should be possible to control the RAFT polymerization initiated by a CTA through the adjustment of the temperature of polymerization in such manner that initiation is tailored to proceed at faster rate (at higher temperature) in comparison to propagation (lower temperature). For the specific CTAs studied in this work, the polymerization rate of styrene was high in the case of the reinitiating cyano (CN)‐substituted group (R group) compared to the other groups studied. The results further show that 4‐cyano pentanoic acid group is superior to the other R groups used for the RAFT polymerization of styrene, especially based on the polydispersity at a given conversion as well as the variation in the expected and experimental number‐average‐molecular weights. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013     

Construction of PIB‐b‐PDEAEMA well‐defined amphiphilic diblock copolymers via sequential living carbocationic and RAFT polymerization

A series of well‐defined amphiphilic diblock copolymers consisting of hydrophobic polyisobutylene (PIB) and hydrophilic poly(2‐(diethylamino)ethyl methacrylate) (PDEAEMA) segments was synthesized via the combination of living carbocationic polymerization and reversible addition fragmentation chain transfer (RAFT) polymerization. Living carbocationic polymerization of isobutylene followed by end‐capping with 1,3‐butadiene was first performed at ?70 °C to give a well‐defined allyl‐Cl‐terminated PIB with a low polydispersity (M_w/M_n =1.29). This end‐functionalized PIB was further converted to a macromolecular chain transfer agent for mediating RAFT block copolymerization of 2‐(diethylamino)ethyl methacrylate at 60 °C in tetrahydrofuran to afford the target well‐defined PIB‐b‐PDEAEMA diblock copolymers with narrow molecular weight distributions (M_w/M_n ≤1.22). The self‐assembly behavior of these amphiphilic diblock copolymers in aqueous media was investigated by fluorescence spectroscopy and transmission electron microscope, and furthermore, their pH‐responsive behavior was studied by UV‐vis and dynamic light scattering. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 1478–1486