活性负离子聚合法制备POSS基七臂星形聚合物及其表征

首先利用高真空活性负离子聚合方法制备聚异戊二烯锂(PI-Li)和(聚苯乙烯-b-聚异戊二烯)锂(PS-PI-Li)活性链,再与单羟基七乙烯基多面体齐聚倍半硅氧烷(VPOSS-OH)发生加成反应,一步法制备2种含羟基的七臂星形聚合物.用分级沉淀法去除低加成产物,即可得到纯的七臂星形聚合物7PI-POSS-OH和7(PS-PI)-POSS-OH,利用凝胶渗透色谱(GPC)、核磁共振波谱(1H-,13C-NMR)、红外光谱(FTIR)和基质辅助激光解吸电离飞行时间质谱(MALDI-TOF MS)表征了聚合物的化学结构、分子量及分子量分布,并通过热失重分析(TGA)测试了聚合物的热分解温度.     

负离子聚合制备环氧化八臂星形聚异戊二烯及其表征

利用仲丁基锂引发异戊二烯进行高真空负离子聚合制备聚异戊二烯基锂活性链(PI-Li),再与八乙烯基多面体齐聚倍半硅氧烷(OVPOSS)在环己烷中发生加成反应,一步法制得八臂星形聚合物.利用分级沉淀去除稍过量的的线型聚异戊二烯以及低加成产物,即可得到纯的八臂星形聚异戊二烯(8PI-POSS).最后,通过甲酸/过氧化氢对8PI-POSS中的聚异戊二烯链进行部分氧化反应,获得环氧化八臂星形聚异戊二烯(8EPI-POSS).利用核磁共振波谱(~1H-,~(13)C-NMR)、凝胶渗透色谱(GPC)、傅里叶变换红外光谱(FTIR)和基质辅助激光解吸电离飞行时间质谱(MALDI-TOF MS)对聚合物的化学结构、分子量及分子量分布进行表征.实验结果表明,通过调节单体与引发剂的摩尔比,成功合成了不同聚合度的8PI-POSS和8EPI-POSS;并且通过改变氧化反应的温度和时间以及氧化试剂的用量,可以简易改变8EPI-POSS的环氧度.最后,通过热失重分析(TGA)测试了几种聚合物的热分解温度,结果显示,PI均聚物在200oC左右开始分解,而由于POSS的引入,8PI-POSS和8EPI-POSS在340oC左右才开始分解,并且与PI均聚物相比,在800oC还有大概3%的残留组分.     

星型POSS/PMMA复合材料的ATRP合成及其热性能研究

以γ-氯丙基三乙氧基硅烷为原料合成八官能团γ-氯丙基多面体低聚倍半硅氧烷(POSS),以该POSS为引发剂,通过原子转移自由基聚合(ATRP)合成具有星型结构的POSS/PMMA复合材料.通过傅立叶红外(FTIR)、核磁共振(NMR)、凝胶渗透色谱(GPC)和X-射线衍射(XRD)等手段对POSS和POSS/PMMA的化学组成和结构进行了表征,结果表明已经合成八官能团γ-氯丙基POSS,POSS/PMMA复合材料具有分子设计的预定结构,且复合材料的分子结构得到了较好的控制.通过ATRP法实现了POSS在聚合物中的单分散.此外,TGA的研究表明,POSS的引入提高了聚合物的热稳定性.     

POSS基树枝状大分子的合成与应用

树枝状大分子(dendrimer)是一种高度支化、纳米尺度的人工合成大分子,具有独特的物理化学性能和重要的应用前景。利用具有8个可官能化顶点的多面体低聚倍半硅氧烷(POSS)作为树枝状大分子的核心,可在一定程度上简化树枝状大分子繁琐的合成与分离过程,在低代数时就可获得较大的表面官能团密度,并使树枝状分子呈现球形对称结构。POSS基树枝状大分子结合了POSS和树枝状分子结构与性能的优势,是一类极具潜力的有机-无机纳米杂化材料。本文综述了近年来POSS基树枝状大分子的最新研究成果,介绍了具有代表性的POSS基树枝状大分子的合成方法以及它们在催化剂、生物材料、液晶材料和发光材料等领域的应用研究进展,并对该新型材料的发展趋势做了展望。     

POSS/聚氨酯复合材料结构与性能的研究进展

多面体低聚倍半硅氧烷(POSS)是新兴的有机/无机杂化材料,其特殊的笼状结构可以从纳米尺度上影响聚氨酯体系的结晶行为、微相分离程度、交联密度等结构特征。少量添加即可大幅提高聚氨酯的耐水性、热稳定性、力学性能,以及阻燃性能、黏结性能、韧性等。本文从POSS/聚氨酯复合材料的结构出发,介绍了化学合成POSS基聚氨酯及物理共混POSS/聚氨酯复合材料,总结分析了悬垂型、星型、串珠型以及物理混合POSS基聚氨酯复合材料的结构特点,以及POSS结构差异对其复合材料性能的影响与影响机理。     

含POSS侧基的非环二烯烃易位聚合及离子型杂化聚合物表征

基于七异丁基-胺丙基-多面体低聚倍半硅氧烷(POSS-NH₂)与溴丁烯或溴代十一烯反应, 一步法合成了含POSS侧基的两种杂化二烯烃. 以钌卡宾络合物为催化剂的非环二烯烃易位(ADMET)聚合, 短链二烯烃未能发生, 而长链二烯烃能顺利实现. 将杂化二烯烃转变为离子型杂化二烯烃, 其ADMET聚合活性较高, 随着反应时间延长, 聚合物分子量明显增大, 分子量分布变窄, 体现了逐步聚合的特征. 核磁共振分析揭示了聚合物的不饱和结构和聚合反应的变化过程. 主链不饱和的无定形聚合物, 经氢化作用转变为饱和的离子型杂化聚乙烯, POSS基团精确地连接在聚乙烯骨架的侧位上, 且POSS基团和聚乙烯骨架均表现出较强的结晶能力. 这种离子型杂化聚乙烯具有球形的单分子或聚集形态, 可直接构筑纳米尺度的聚合物材料.     

不同拓扑结构的POSS/聚合物的合成及热稳定性的研究

以单官能团笼状倍半硅氧烷(POSS)、八官能团笼状倍半硅氧烷(POSS)分别为引发剂,CuCl/2,2联吡啶为催化剂,采用原子转移自由基聚合方法制备了"蝌蚪"形、星形POSS/PMMA和POSS/PMMA-b-PS复合材料。研究结果表明:通过ATRP法,能成功制备具有特定结构的POSS/PMMA和POSS/PMMA-b-PS复合材料。相比于纯的聚合物基体,星形POSS/PMMA复合材料的热稳定性降低,"蝌蚪"形POSS/PMMA复合材料的热稳定性提高。"蝌蚪"形POSS/PMMA-b-PS比星形POSS/PMMA-b-PS的热稳定性好。     

HBPS-PEO多臂星形聚合物电解质的合成及离子导电性的研究

通过叠氮化超支化聚苯乙烯(HBPS-N3)与端炔基聚乙二醇单甲醚(ay-PEO)的点击反应,合成了以超支化聚苯乙烯(HBPS)为核、不同分子量的聚氧化乙烯(PEO)为臂的多臂星形聚合物(HBPS-PEO),并利用ATR-FTIR,1H-NMR,GPC对合成的星形聚合物的结构进行了表征.将该种星形聚合物与双三氟甲基磺酰亚胺锂(LiTFSI)进行复合,制备了星形聚合物为基体的聚合物电解质,通过交流阻抗技术和DSC对该聚合物电解质的离子导电性能及热性能进行了研究.结果表明,星形结构可以在一定程度上抑制结晶的形成,这种新型的星形聚合物电解质的室温电导率明显高于相应的线形聚合物电解质,当n(EO)/n(Li)=40,PEO臂的分子量为1000时,该星形聚合物电解质的离子电导率最高,30℃时为6.7×10-5Scm-1,40℃时可以达到1.2×10-4Scm-1;TGA结果表明,制备的星形聚合物的初始分解温度(Tonset)都高于360℃,具有良好的热稳定性.     

官能团化聚己内酯的合成与表征

通过分子结构设计合成了新型含有侧基官能团的聚己内酯材料.首先,通过亲核加成反应,由溴乙酸乙酯与烯胺合成2-乙氧甲酰甲基环己酮;然后以间氯过氧化苯甲酸为氧化剂,通过Baeyer-Villiger氧化反应,得到带有官能团的己内酯单体,6-乙氧甲酰甲基-ε-己内酯;该单体在异辛酸亚锡(Sn(Oct)2)的催化下,本体开环聚合得到相应的均聚物及其与ε-己内酯的共聚物.采用1H-NMR、13C-NMR、GPC和DSC表征了聚合物的结构和热力学性能.随着6-乙氧甲酰甲基-ε-己内酯在共聚物中的含量增加,共聚物的分子量降低,同时熔点和熔融焓也随之降低.     

POSS基杂化含氟丙烯酸酯共聚物涂膜的表面相分离与疏水性研究

采用自由基溶液聚合法成功合成了多面体低聚倍半硅氧烷(POSS)基杂化含氟丙烯酸酯共聚物,并采用核磁共振仪(NMR)和凝胶渗透色谱仪(GPC)表征了共聚物,其中POSS和含氟单体分步加入到反应中.首先将共聚物溶解到三氟三氯乙烷(F113)和乙酸乙酯的混合溶剂中配制成溶液,然后通过直接在玻璃片上滴落共聚物溶液制备了共聚物涂膜.采用扫描电子显微镜(SEM)、X-射线光电子能谱(XPS)、原子力显微镜(AFM)和接触角测量仪考察了F113和乙酸乙酯的配比对共聚物涂膜表面形貌、表面元素组成、表面粗糙度以及表面疏水性的影响.实验数据表明POSS在表面能够聚集成纳米颗粒并能极大增强涂膜表面粗糙度和疏水性.共聚物表面同时存在POSS聚集与有机相微相分离两类相分离行为,并形成了复合粗糙结构.虽然POSS和含氟段竞争迁移到表面,但是随着混合溶剂中F113的增多,涂膜表面含氟量越来越多,同时POSS在表面的聚集体越来越少,表面平均粗糙度越来越小,最终涂膜的疏水性越来越强,这说明F113有助于提升氟的趋表迁移能力,使涂膜表面含氟链段占据较多的表面空间,从而抑制了POSS在表面聚集分布.当使用纯F113作为溶剂时,共聚物涂膜的表面氟含量为45.25%,平均粗糙度为93.4 nm,此时静态水接触角最大为135.0?,表现出优异的疏水性.     

Bridged polyhedral oligomeric silsesquioxane (POSS): A potential member of silsequioxanes

Two novel and well-defined polyhedral oligomeric silsesquioxanes（POSS） with two same Si₈O₁₂ cores and a reactive NH group, namely bridged-POSS（2a and 2b）,have been prepared by the traditional ’corner-capping’ reaction.X-ray diffraction demonstrates that those two POSS have the similar T₈ structure.From the thermo-gravimetric analysis,bridged-POSS shows the belter thermal degradation stability than the contrastive POSS.     

Poly(ethylene imine) hybrids containing polyhedral oligomeric silsesquioxanes: Preparation, structure and properties

Both octaglycidyletherpropyl polyhedral oligomeric silsesquioxane and hepta(3,3,3-trifluoropropyl)glycidyletherpropyl polyhedral oligomeric silsesquioxane were synthesized via the hydrosilylation reactions between octahydrosilsesquioxane [and/or hepta(3,3,3-trifluoropropyl)hydrosilsesquioxane] and allyl glycidyl ether. The polyhedral oligomeric silsesquioxane (POSS) macromers were characterized by means of Fourier transform infrared and nuclear magnetic resonance spectroscopy. The inter-component macromolecular reactions between the POSS macromers and poly(ethylene imine) (PEI) were employed to prepare the POSS-containing organic-inorganic PEI hybrids. The inclusion of octaglycidyletherpropyl POSS into PEI results in the formation of the organic-inorganic hybrid networks whereas the introducing hepta(3,3,3-trifluoropropyl)glycidyletherpropyl POSS to PEI affords the linear POSS-grafted PEI copolymers. Differential scanning calorimetry and thermogravimetric analysis show that the POSS-containing PEI hybrids displayed increased glass transition temperatures (T_g’s) and enhanced thermal stability compared to the plain PEI. These PEI hybrid composites can be significantly swollen with water without dissolving, suggesting the formation of hydrogels. The PEI hydrogels containing octaglycidyletherpropyl POSS is in reality the chemically-crosslinked hydrogels whereas the those containing hepta(3,3,3-trifluoropropyl)glycidyletherpropyl POSS displayed the behavior of physical hydrogels. The formation of physical hydrogels is ascribed to the microphase-separated morphology in the hybrids. In addition, the hybrids containing hepta(3,3,3-trifluoropropyl)glycidyletherpropyl POSS exhibited the typical amphiphilicity as evidenced by the increase in surface hydrophobilicity.     

直接熔融聚合法制备以胆酸为核的星型聚(D,L-乳酸)药物缓释材料及其表征

以廉价的外消旋乳酸(D,L-LA)为原料,胆酸为核,氧化亚锡为催化剂,采用熔融聚合法合成了星型结构的胆酸-聚(D,L-乳酸)共聚物,分别考察了预聚时间、催化剂种类、用量以及熔融共聚时间等的影响,并用FT-IR、1HNMR、GPC等对共聚物进行了表征。当胆酸和乳酸的投料比(以物质的量计)为1∶64、预聚8h、熔融共聚8h、熔融温度160℃、催化剂用量0.3%时,以51.9%的产率生成了重均分子量(Mw)达5600(分散度Mw/Mn=1.37)的共聚物。分析表明,每个星型结构高分子中含有一个胆酸单元核心。本方法步骤少,有利于该类含特殊功能基团的药物缓释材料的廉价、快速合成。     

Highly stretchable and self-healing hydrogels based on poly(acrylic acid) and functional POSS

Herein, we present a novel way for the production of self-healing hydrogels with stretch beyond 4200% than their initial length and relatively high tensile strength(0.1?0.25 MPa). Furthermore, the hydrogel was insensitive to notch. Even for the samples containing V-notches, a stretch of 2300% was demonstrated. The hydrogels were developed by in situ crosslinking of the self-assembled colloidal poly(acrylic acid)(PAA)/functionalized polyhedral oligomeric silsesquioxane(POSS) micelles. This was achieved by the addition of functionalized polyhedral oligomeric silsesquioxane with tertiary amines and hydroxyls(POSS-AH) into the PAA reaction solution. The POSS-AH led to micellar growth, then the dualcrosslinked network was constructed. One type of crosslink was formed by hydrogen-bonding and ionic interactions between PAA chains and POSS-AH, the other type of crosslink was formed by covalent bonds between PAA and bis(N,N'-methylenebis-acrylamide).     

Study on thermal degradation and combustion behaviors of PC/POSS hybrids

Polycarbonate/polyhedral oligomeric silsesquioxane hybrids were prepared based on bisphenol A polycarbonate (PC) and trisilanolphenyl-POSS (TPOSS) by the melt blending method. Investigation of transmission electronic microscopy and Fourier transform infrared spectroscopy confirms that the nanoscale TPOSS particles were well dispersed in the PC matrix and there is no chemical reaction between the TPOSS particles and PC matrix during the melt blending. The thermal degradation behaviors of the PC/TPOSS hybrids were investigated. The presence of TPOSS significantly affects the thermal degradation process of PC. The combustion behaviors of the hybrids were evaluated by cone calorimetry experiments. The addition of TPOSS significantly decreased the value of peak heat release rate of the hybrids. Moreover, the addition of TPOSS at 2 wt% leads to the maximum decrease of the PHRR. And scanning electron microscopy and X-ray photoelectron spectroscopy were used to explore the char residues of the pure PC and the hybrids.     

聚甲基丙烯酸甲酯/星形聚乙二醇半互穿聚合物网络的形状记忆性能和分子机理

采用非共价复合方法,设计并合成了具有星形结构的聚甲基丙烯酸甲酯/星形聚乙二醇半互穿聚合物网络(PMMA/SPEG)和聚甲基丙烯酸甲酯/线性聚乙二醇半互穿聚合物网络(PMMA/LPEG).研究了PEG分子量对PMMA/SPEG和PMMA/LPEG的热性能、机械性能、动态机械性能和形状记忆性能的影响.结果表明,与PMMA/LPEG相比,星形结构的嵌入显著提高了PMMA/SPEG复合物的机械性能、形状回复率和回复速度.采用Edwards管道模型理论对其形状记忆效应的分子机理进行了阐释,利用材料的应力松弛特性对机理分析进行了验证.     

不同内核结构PEG-b-PCL胶束的制备及其载药性能的研究

以聚乙二醇单甲醚作大分子引发剂,异辛酸亚锡作催化剂,将不同比例的ε-己内酯(CL)与4-甲基-ε-己内酯(MCL)单体开环共聚,并通过控制CL和MCL的投料比以及投料方式,得到了疏水链段上CL和MCL不同比例和分布的4组聚合物.核磁和凝胶渗透色谱法表征了聚合物的结构,示差扫描量热法,广角X射线衍射和红外光谱表征了聚合物的结晶性.采用透析的方法,制备了4种聚合物的纳米胶束,以及载药(阿霉素DOX)胶束,并研究了胶束的自组装行为以及对阿霉素的包裹和释放情况.结果表明MCL单体的引入降低了聚合物的结晶性,提高了对DOX的载药量,加快了DOX的释放.通过激光共聚焦显微镜和流式细胞仪研究了Hep G2肝癌细胞对不同内核结构载药胶束的内吞情况,并用MTT法考察了胶束对细胞的毒害作用,细胞实验发现,Hep G2细胞对载DOX胶束的内吞以及载DOX胶束对细胞的杀伤能力和胶束内核的结构相关.     

Positive Luminescent Sensor for Aerobic Conditions Based on Polyhedral Oligomeric Silsesquioxane Networks

There are numerous numbers of hypoxia-selective luminescent probes based on oxygen quenching of phosphorescence.We show a unique design for luminescent probes to detect hyperoxia utilizing hybrid networks consisting of aggregation-induced emission(AIE)-active dyes and disulfide linkers.At the initial state,emission from the AIE-active dyes is inducible by suppressing energy-consumable intramolecular motions in the hybrid matrices,while the decrease in intensity was detected by releasing molecular motions corresponded to bond scission at the disulfide linkers.Particularly,it was shown that this process selectively proceeds in hypoxia.As a result,positive luminescent signals were obtained in hyperoxia.