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。     

用ATRP法构筑核壳型梯度极性的多羟基多臂星状超支化聚合物及聚合物刷——三层聚合物刷的合成与表征

设计并通过原子转移自由基聚合方法 (ATRP)合成了核壳型具有梯度极性的多羟基多臂星状聚合物刷 .端羟基超支化聚 (3 乙基 3 羟甲基氧杂环丁烷 )与 2 溴 异丁基酰溴反应制得大分子引发剂 (HP Br) ,以Cu(I)Br和N ,N ,N′ ,N′ ,N″ 五甲基二乙基三胺 (PMDETA)为催化体系 ,进行甲基丙烯酸甲酯 (MMA)的ATRP反应 ,得到以甲基丙烯酸甲酯为臂的多臂星状超支化聚合物 (HP g PMMA) .又以HP g PMMA为引发剂 ,进行甲基丙烯酸羟乙酯 (HEMA)的ATRP聚合 ,得到核壳型具有梯度极性的多羟基多臂星状超支化聚合物 (HP g PMMA b PHEMA) ,继续将其羟基官能团溴代化 (与 2 溴 异丁基酰溴反应 ) ,引发HEMA的ATRP溶液聚合 ,得到了多臂星状超支化聚合物刷 .产物的结构用1 H NMR、FTIR、GPC等进行了表征和测试 .     

丙烯酰胺多面体低聚倍半硅氧烷在超临界CO2中的RAFT聚合

以超临界CO₂为聚合介质, 硫代苯甲酰基特丁基硫酯(TTBT)为链转移剂, 通过可逆加成-断裂链转移(RAFT)聚合制备了聚丙烯酰胺多面体低聚倍半硅氧烷(PAMPOSS)均聚物及其与甲基丙烯酸甲酯(PMMA)的嵌段共聚物(PAMPOSS-b-PMMA). 对产物结构组成和分子量及其分布进行表征. 结果表明, 在TTBT的控制下, POSS的均聚物和嵌段共聚物具有高分子量及窄分子量分布. 含POSS单体在超临界CO₂中为均相聚合, POSS聚合物的结晶性在一定程度上影响其在超临界CO₂中溶解性.     

AB_2型星形杂臂偶氮液晶聚合物的合成及表征

通过原子转移自由基聚合(ATRP)与ATRP衍生物化学修饰结合的方法,合成了一系列AB2型星形杂臂偶氮液晶聚合物.其中,A为聚苯乙烯,B为聚6-[4-(4′-甲氧基苯基)偶氮苯氧基己酯](PMMAZO).合成分三步进行.首先,以ATRP方法得到ω-溴聚苯乙烯活性链PS(Br).然后对PS(Br)进行化学改性,得到带两个末端溴原子的聚苯乙烯活性链PS(Br)2·最后,以PS(Br)2作为双官能团大分子引发剂,引发6-[4-(4′-甲氧基苯基)偶氮苯氧基]己酯(MMAZO)发生ATRP聚合,得到星形杂臂PS(PMMAZO)2聚合物.进一步对聚合产物进行了GPC和1H-NMR分析.结果表明合成产物是预期的星形杂臂聚合物,产物分子量可控且分子量分布狭窄.同时,以DSC和POM表征了星形杂臂聚合物的液晶性.     

γ-取代丙基环四硅氧烷的合成及其与D_4的乳液共聚反应

本文合成了四种γ-取代丙基环四硅氧烷。通过阳离子型和阴离子型乳液共聚的方法,分别使其与八甲基环四硅氧烷共聚,合成了含有γ-羟丙基、γ-氯丙基和γ-乙酰氧丙基等活性碳官能团有机硅聚合物的稳定乳液;研究了乳液共聚反应过程中的单体转化率、聚合物分子量的变化以及温度、催化剂、乳化剂、取代基团等因素的影响。     

POSS星型聚合物对PMMA复合凝胶聚合物电解质性能的影响

为了提高凝胶聚合物电解质(GPE)的离子传输性,以低聚倍半硅氧烷(POSS)为核,臂结构为聚甲基丙烯酸甲酯(PMMA),臂聚合度不同的八臂星型聚合物(POSS-(PMMA3)8、POSS-(PMMA6)8、POSS-(PMMA9)8)为改性剂,分别与PMMA共混制备复合GPE,研究了POSS星型聚合物臂结构对复合GPE电性能影响的规律.结果表明,POSS星型聚合物的引入,使得复合GPE的电导率较纯PMMA基GPE均有显著提高,其中臂聚合度较小的POSS-(PMMA3)8复合GPE在室温的电导率最大,比纯PMMA基GPE提高了3.5倍.分析了该星型聚合物不同含量以及锂盐浓度等对复合凝胶聚合物电解质的影响,发现锂盐浓度在凝胶体系中为0.6 mol/L,该星型聚合物含量为聚合物基体15 wt%时,复合凝胶聚合物电解质电导率最大为2.73×10-4S/cm.研究了温度对复合凝胶聚合物电解质离子传输性能的影响规律,发现其离子传输规律符合Arrhenius方程.在此基础上,提出了该凝胶电解质体系的离子传输微观结构模型.     

ATRP与点击化学结合制备树状星型聚合物

本文通过将ATRP技术和点击化学相结合的方法来制备树状星型聚合物[(PMMA)2PSt]4. 首先通过1,3-偶极环加成反应对ATRP的核预聚物进行端基修饰, 得到后继ATRP反应的大分子引发剂, 进而引发第二单体的ATRP聚合生成树状星型聚合物.     

结构可控的聚合物长短刷接枝纳米粒子

通过RAFT聚合制备了一系列窄分子量分布的聚(γ-甲基丙烯酰氧基丙基三乙氧基硅烷)(PTEPM)-b-聚甲基丙烯酸甲酯(PMMA)嵌段共聚物和PTEPM、PMMA低聚物.将具有不同PMMA分子量的2种PTEPM-b-PMMA共聚物与低聚物PMMA或PTEPM进行共组装(微相分离),形成片、柱、球等不同PTEPM相区结构.采用盐酸气氛处理,PTEPM相区水解交联形成倍半硅氧烷SiO1.5内核,分离纯化得到聚合物长短刷接枝纳米粒子.使用这种相分离-交联-分散制备方法,调节嵌段共聚物分子结构和三组分比例,可实现聚合物接枝纳米粒子内核形状和尺寸、接枝密度、长短刷比例、长刷长度的精确调控.这些纳米粒子是研究聚合物纳米复合材料结构-性能关系的理想模型体系.     

紫外光固化超支化聚硅氧烷的合成及其光固化动力学研究

利用γ-甲基丙烯酰氧基丙基三甲基硅氧烷的受控水解反应即A2-B3单体对法来制备超支化聚硅氧烷,并对合成出的聚合物通过FT-IR、1H-NMR和多角度激光光散射技术(MALLS)进行了表征.结果表明,所得聚合物具有超支化结构且分子中含有大量活性官能团,从而可以实现紫外光引发固化.通过等温差示光量热实验(DPC)研究了聚合物结构、引发剂用量、光强度和聚合温度对聚合物光固化行为的影响规律,并得到了其中一种聚合物的光固化动力学参数,光固化反应总级数约为3,表观活化能为16.9kJ/mol.     

具有温敏性的混合胶束的制备与表征及药物体外释放

通过原子转移自由基聚合(ATRP)合成了以胆固醇为端基的两亲性聚(N-异丙基丙烯酰胺)(Chol-PNIPAAm),利用FTIR、1H-NMR和GPC等方法表征了聚合物的结构.将该两亲性温敏聚合物与聚乙二醇单甲醚硬脂酸酯(mPEG-SA)通过简单混合,即可得到稳定的Chol-PNIPAAm/mPEG-SA混合胶束体系....     

Synthesis of silsesquioxane nanocomposites

In order to investigate the effect of presence of well defined nano-sized inorganic particles on the molecular mobility a conformation statistics of polymer chains, well defined polystyrene (PS) and poly(methyl methacrylate) (PMMA) macromolecules containing polyhedral oligomeric silsesquioxanes nanoparticles (POSS) were synthesized by copper-mediated atom transfer radical polymerization (ATRP). Two approaches were used for the synthesis — the first involves POSS as the initiator of ATRP; the second way considers an addition of POSS to the polymer (prepared by ATRP) with an appropriate functional group. Kinetics of polymerization was determined using common analytical methods and it was compared to the polymerizations initiated by low-molecular weight initiators, regarding the polymerization rate, initiation efficiency and polydispersity of the polymer. Efficiency of the initiation with POSS-containing initiators was low, causing remnants of inseparable free POSS in polymer. The second approach bypassed these disadvantages —POSS is connected to the polymer through a pending allyl group using the very efficient hydrosilylation reaction. Presented at the 1st Bratislava Young Polymer Scientists Workshop, Bratislava, 20–23 August 2007.     

原子转移自由基法合成八臂星型聚苯乙烯

设计合成了星型聚合物引发剂四(2,2-二氯乙酸)季戊四醇酯(TDCAP), 并通过原子转移自由基聚合合成了八臂星型聚苯乙烯. 用FTIR, 1H NMR和GPC等手段对引发剂和星型高分子的结构进行了表征.     

Reverse Atom Transfer Radical Polymerization of MMA in the Presence of CaCO3/SiO2 Two-Component Composite Particles

Summary: We previously discovered that structurally well-defined polymer/inorganic composite particles, i.e., poly(methyl methacrylate) (PMMA)/CaCO₃/SiO₂ three-component composite particles, can be achieved via reverse atom transfer radical polymerization (ATRP), using 2,2′-azo-bis-isobutyronitrile as initiator and Cu^II bromide as catalyst. In the present study, the influence of the mass ratio of CaCO₃/SiO₂ two-component composite particles to methyl methacrylate (MMA) on the rate and behavior of the polymerization was studied in detail. The results illustrate that increasing the mass ratio of CaCO₃/SiO₂ two-component composite particles will decrease the overall rate of polymerization of MMA under standard reverse ATRP conditions. Thermal properties of the obtained well-defined particles were characterized and determined by thermogravimetric analysis (TGA). The results indicate that well-defined PMMA chains grafted on the surface of CaCO₃/SiO₂ particles were only degraded by random chain scission of C C linkages within the PMMA chain, which is different from the degradation of PMMA chains prepared via traditional radical polymerization. This difference is reasonably ascribed to the difference between the end groups of PMMA prepared via reverse ATRP and that via traditional radical polymerization, which has been confirmed by end group analysis measured by ¹H–NMR spectroscopy.     

ATRP法制备两亲性嵌段共聚物的研究

以α 溴代丙酸乙酯 (EPN Br)为引发剂、氯化亚铜 (CuCl)和联二吡啶 (bpy)组成的混合体系为催化剂 ,引发苯乙烯聚合 ,得到了端基为卤原子的单分散聚苯乙烯 (PS X)预聚体 .以此PS X为大分子引发剂、CuCl和N ,N ,N′ ,N″ ,N″ 五甲基二亚乙基三胺 (PMDETA) bpy的混合体系为催化剂 ,引发N ,N 二甲基丙烯酰胺(DMAA)聚合 ,得到了分子量分布较窄的聚苯乙烯 b 聚N ,N 二甲基丙烯酰胺 (PS b PDMAA)两亲性嵌段共聚物 .考察了大分子引发剂的分子质量、聚合介质及配位剂等对聚合过程的影响 .并用GPC、IR、1 H NMR等对产物进行了表征 .研究结果表明 ,该聚合反应体系符合原子转移自由基聚合的特征 .     

Synthesis of Poly(methyl methacrylate) Labeled with Fluorescein Moieties via Atom Transfer Radical Polymerization

Fluorescein chromophore‐labeled poly(methyl methacrylate) (PMMA) was prepared via atom transfer radical polymerization (ATRP) with two novel bromine‐containing fluorescein derivatives, 3,6‐bi(2′‐bromo‐2′‐methyl‐propionic acid) fluorescein ester (Fla‐Br) and 3‐(2′‐bromo‐2′‐methyl‐propionic acid) fluorescein ester (Flb‐Br), as the functional initiators, and CuBr/PMDETA as the catalyst, respectively. The above mentioned fluorescein containing bromine were synthesized in our lab. The ATRP of PMMA was proved in a controlled fashion. The resultant PMMA with narrow molecular weight distribution was endowed with the fluorescein chromophore incorporated into the polymer backbone. The presence of the fluorescein labeling of the polymers was confirmed by ¹H‐NMR and GPC trace under UV detector. The UV spectroscopy and fluorescence measurements of the resultant polymer gave further evidence of the functionality of the fluorescein labeling.     

Octafunctional cubic silsesquioxane (CSSQ)/poly(methyl methacrylate) nanocomposites: Synthesis by atom transfer radical polymerization at mild conditions and the influence of CSSQ on nanocomposites

Organic/inorganic hybrid star‐like nanocomposites from two different octafunctional cubic silsesquioxane (CSSQ) nano‐cage cores and poly(methyl methacrylate) (PMMA) were synthesized using atom transfer radical polymerization (ATRP) at mild conditions, in which octafunctional octakis(3‐hydroxypropyldimethylsiloxy)octasilsesquioxane (OHPS) and octa(aminophenyl)silsesquioxane (OAPS) nano‐cages were used as ATRP initiators. The polymerization was carried out at 50 °C in acetonitrile/water mixture. ¹H‐NMR and GPC were employed to characterize the obtained nanocomposites. GPC data revealed that the resulting nanocomposites exhibit unimodal and narrow molecular weight distributions indicating well‐controlled synthesis and well‐defined hybrid nanocomposites with star architecture. The influence of CSSQ nano‐cages on the thermal property of nanocomposites was investigated using differential scanning calorimetry and thermal gravimetric analysis (TGA). It was observed that the nanocomposites exhibit significantly higher glass transition temperature compared with its linear counterpart because of slow relaxation caused by the star‐like architecture. TGA study, however, did not reveal any significant improvement in thermal stability of nanocomposites as compared with linear PMMA. Finally, field emission scanning electron microscopy images of fractured surfaces of nanocomposite sample films showed well dispersed CSSQ nano‐cages in PMMA matrix without phase separation. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 766–776, 2008     

甲基丙烯酸甲酯的反向原子转移自由基聚合反应 研究

在较低的温度(60℃)和较低的AIBN/CuCl~2/配位剂摩尔比(1:2:4)条件下,用乙腈为溶剂,实现了甲基丙烯酸甲酯(MMA)的反向原子转移自由基聚合(RATRP)。联二吡啶(bpy)为配位剂时,所合成的聚甲基丙烯酸甲酯(PMMA)的分子量分布可低至1.08。用1,10-菲咯啉(phen)代替bpy,MMA的聚合反应速率加快,但其分子量分布稍宽(1.40左右),并进一步研究了bpy和phen作为混合配位剂时对MMA反向ATRP聚合的影响。用RATRP反应所得的带有卤素端基的PMMA作为苯乙烯ATRP的大分子引发剂,成功地合成了具有预期结构的苯乙烯与甲基丙烯酸甲酯嵌段共聚物,大分子引发剂的引发效率接近于1,说明在RATRP过程中由自由基引发剂引发MMA进行一般自由基聚合反应的可能性甚微。     

Benzyl Bromide Functionalized Poly(Phenyleneethynylene)s as Macroinitiators in the Atom Transfer Radical Polymerization of Methyl Methacrylate

Abstract

The behavior of benzyl bromide functionalized poly(phenyleneethynylene)s as macroinitiators in the atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA) was investigated. The ¹H NMR observation of the ATRP using the exclusively para‐linked poly(phenyleneethynylene) macroinitiator PPE1A, and the low molecular weight initiator R‐BzBr, respectively, revealed lower reactivity for the macroinitiator. Comparison of graft copolymers, which were obtained from ATRP of MMA with PPE1A and the partially meta‐linked poly(phenyleneethynylene) PPE1B, showed higher reactivity in the case of PPE1B, expressed by a larger degree of polymerization in the PMMA side chains, as well as higher initiatior efficiency. This might be caused by better solubility of the less symmetric PPE1B. Investigation of the graft copolymers PPE2A and PPE2B was carried out by means of ¹H NMR spectroscopy, gel permeation chromatography (GPC) as well as UV/vis spectroscopy. Impairment of the delocalized π‐electron system of the conjugated polymers during the ATRP was not detectable.