高氯酸锂的二甲基硅氧烷-环氧乙烷共聚物溶液的电导和弛豫

本文系统地研究了高氯酸锂的二甲基硅氧烷-环氧乙烷共聚物溶液(简写为DMS:EO:LiClO_4)的电导和弛豫随温度和盐浓度的变化规律。浓度为0.394 molL~(-1)时室温电导率达到极大值, 大于10~(-4)S cm~(-1)。通过比较发现, DMS与PEO形成共聚物并含有易离解的盐将促进离子运动。本文也提到只通过加热使这种溶液固化成膜的方法及膜的电导。     

新型PLA-PVP两亲性交联共聚物的初步研究

先以聚乙二醇(PEG)为中心嵌段,经消旋-丙交酯(D,L—LA)开环扩链,进而用丙烯酸酯封端制备了可生物降解交联剂。然后以辛酸亚锡为催化剂、甲基丙烯酸羟乙酯(HEMA)为共引发剂引发D,L—LA开环聚合,制备了末端双键功能化的大分子单体(PLA-HEMA)。最后以可降解交联剂、大分子单体和N-乙烯基吡咯烷酮(NVP)为原料,采用自由基聚合方法合成了新型可生物降解两亲性交联共聚物,并对其亲水性和力学性能进行了研究。     

侧链含卤素基团聚芳醚酮的合成及性能

通过分子设计, 合成了新型含碘基苯基的双酚单体4-碘苯基对苯二酚(I-Ph-HQ), 利用上述单体与含氟双酚单体(3-三氟甲基)苯基对苯二酚和氟酮通过亲核取代缩聚反应合成了一系列侧链含卤素基团的聚芳醚酮共聚物(PEEK-CF₃-I). 通过FTIR和 ¹H NMR等测试手段, 表征了共聚物的化学结构. 研究了所合成的PEEK-CF₃-I共聚物的介电性能、热性能和机械性能, 探讨了共聚物中含碘侧基和含氟侧基含量的变化及对材料各项性能的影响. 研究表明, 共聚物中含碘侧基含量的增加能够显著提升共聚物的玻璃化转变温度, 其中共聚物材料PEEK-CF₃-I-10%的玻璃化转变温度为153 ℃, 同时材料依然能够保持优异的机械性能和较低的介电常数.     

稀土络合催化苯乙炔直接成膜聚合 Ⅰ.环烷酸钕盐络合催化苯乙炔直接成膜聚合

首次应用环烷酸钕-三异丁基铝络合催化体系在己烷-甲苯混合溶剂中,于室温下使苯乙炔直接聚合成膜获得成功。研究了成膜聚合反应特征及动力学行为。发现溶剂及聚合温度的选择是成膜的关键。成膜的临界条件为:[Nd]>1×10~(-5)mol/ml;[M]≥1×10~(-4)mol/ml;Al/Nd>1(摩尔比)。成膜聚合具有典型的链锁聚合反应特征,在适宜的聚合条件下,转化率可达96.5％。在不同溶剂和不同温度下聚合反应速率不同。聚苯乙炔膜可为黄色、橙色或红色,这与聚合时间、温度、单体浓度以及己烷/甲苯(体积比)有关。     

EPR-g-PS接枝共聚物的大分子单体共聚物合成及表征

将阴离子聚合所得末端带有烯丙基的窄分布聚苯乙烯大分子单体(PSallyl)与乙烯、丙烯在钒催化体系下进行共聚合,得到聚苯乙烯(PS)支链沿乙丙橡胶(EPR)主干无规分布的接枝共聚物EPR-g-PS。接枝效率为70％左右。大分子单体的分子量、加入量,催化剂浓度和聚合温度等对共聚反应及其产物结构有明显的影响。丁酮为选择沉淀剂可分离未反应的聚苯乙烯大分子单体。用紫外光谱、核磁共振、渗透压和凝胶渗透色谱法测定了纯制接枝共聚物的组成和分子量。结果表明所合成的EPR-g-PS的聚苯乙烯含量为5—45％;支链为分子量1.0—7.8×10~4的窄分布((?)=1.05—1.17)聚苯乙烯;平均支链数为1—4。     

含LiClO4的接枝聚合物网络的结构,形态与离子导电性能研究

聚合物网络快离子导体成膜后有良好的机械强度、尺寸稳定性,但室温电导率稍偏低。本文通过大单体技术合成兼具优良室温电导率(σ_(298K)=4.8×10~(-5)S·cm~(-1))与机械强度的接枝聚合物网络快离子导体,并研究了网络结构、形态与离子导电性之间的关系。 1 实验部分 1.1 试剂及精制 试剂均为化学纯。分子量为800与2000的聚氧化乙烯(PEO800,     

聚乙二醇-聚醋酸乙烯酯-盐复合膜导电性能的研究

采用PEG/PVAc复合物作为高分子固体电解质的基质材料,PEG/PVAc<1/1(mol)时两者有较好的混溶性并破坏了PEG的结晶。研究了高氯酸盐对PEG/PVAc复合膜导电率的影响,结果是随着盐浓度的增加,导电率增大,在同一盐浓度下电导率依次Y(ClO_4)_3>Nd(ClO_4)_3>LiClO_4>NaClO_4,首次将稀土盐用于高分子固体电解质,得到了较高的室温电导率(10~(-6)s·cm~(-1))。加入添加剂以及提高温度和湿度,均能提高复合膜的导电率。     

2-亚甲基丁二酸酐和甲基丙烯酸甲酯的共聚反应研究

2—亚甲基—丁二酸酐(M_1,ITANH)和甲基丙烯酸甲酯(M_2,MMA)在四氢呋喃(THF)中以过氧化二苯甲酰(BPO)作引发剂进行自由基共聚合。由作图法衣得这两种单体在66℃的共聚竞聚率:表明它们趋于嵌均共聚。用粘度法和GPC测量了共聚物的分子量和分子量分布。共聚物在温和的条件下进行部分水解,得到一带有短的羧基侧链的聚电解质[11]。将[11]与无机盐LiClO_4混合后测得电导率δ-2.8272×10~(-4)S·cm~(-1),表明它具有较好的离子导电性。     

聚环氧乙烷大单体与丙烯酸乙酯的共聚及其规整接枝共聚物的表征

本工作研完了末端为甲基丙烯酸酯型的聚环氧乙烷大单体与丙烯酸乙酯的溶液自由基共聚。结果表明,大单体接枝效率和共聚物分子量受单体总浓度、投料比、大单体分子量及引发剂等的影响,接枝效率最高可达90％以上,分子量可在5-15×10~4范围内变化。丙烯酸乙酯与大单体共聚的竞聚率为0.83。共聚物用萃取法精制后,用IR、~1H-NMR、裂解色谱、GPC和膜渗透压计等进行了表征。证实产物有预期的规整接枝共聚物结构。平均接枝数为2—11。     

聚丙烯酸锂与1-丁基-3-甲基咪唑溴离子液体的阳离子交换反应

通过聚丙烯酸锂(PAALi)与1-丁基-3-甲基咪唑溴(BmimBr)离子液体进行阳离子交换, 将1-丁基-3-甲基咪唑阳离子引入到聚丙烯酸锂结构中, 形成了丙烯酸锂(AALi)与1-丁基-3-甲基咪唑丙烯酸盐(BmimAA)离子液体的无规共聚物[P(AALi-BmimAA)]. 研究了反应时间、温度、投料比、反应物浓度及聚丙烯酸锂分子量等对离子交换程度的影响. 对不同离子交换程度时聚合物电导率的研究结果表明, 所有共聚物的电导率均比聚丙烯酸锂的有明显提高, 并且随着阳离子交换程度的增加, 电导率出现极值. 在聚丙烯酸锂的15%水溶液中, 当Bmim+与Li+的投料摩尔比为1∶1时, 在80 ℃下交换反应24 h, 得到的共聚物的Bmim+与Li+摩尔比为0.0387, 其电导率最高, 为1.44×10-8 S/cm, 比聚丙烯酸锂的电导率(1.06×10-11 S/cm)提高了3个数量级. 向此共聚物中掺杂LiTFSI, 电导率再次提高2个数量级, 最高可达2.90×10-6 S/cm.     

Electrodeposition of copper on a Pt(111) electrode in sulfuric acid containing poly(ethylene glycol) and chloride ions as probed by in situ STM

This study employed real-time in situ STM imaging to examine the adsorption of PEG molecules on Pt(111) modified by a monolayer of copper adatoms and the subsequent bulk Cu deposition in 1 M H(2)SO(4) + 1 mM CuSO(4)+ 1 mM KCl + 88 μM PEG. At the end of Cu underpotential deposition (~0.35 V vs Ag/AgCl), a highly ordered Pt(111)-(√3 × √7)-Cu + HSO(4)(-) structure was observed in 1 M H(2)SO(4) + 1 mM CuSO(4). This adlattice restructured upon the introduction of poly(ethylene glycol) (PEG, molecular weight 200) and chloride anions. At the onset potential for bulk Cu deposition (~0 V), a Pt(111)-(√3 × √3)R30°-Cu + Cl(-) structure was imaged with a tunneling current of 0.5 nA and a bias voltage of 100 mV. Lowering the tunneling current to 0.2 nA yielded a (4 × 4) structure, presumably because of adsorbed PEG200 molecules. The subsequent nucleation and deposition processes of Cu in solution containing PEG and Cl(-) were examined, revealing the nucleation of 2- to 3-nm-wide CuCl clusters on an atomically smooth Pt(111) surface at overpotentials of less than 50 mV. With larger overpotential (η > 150 mV), Cu deposition seemed to bypass the production of CuCl species, leading to layered Cu deposition, starting preferentially at step defects, followed by lateral growth to cover the entire Pt electrode surface. These processes were observed with both PEG200 and 4000, although the former tended to produce more CuCl nanoclusters. Raising [H(2)SO(4)] to 1 M substantiates the suppressing effect of PEG on Cu deposition. This STM study provided atomic- or molecular-level insight into the effect of PEG additives on the deposition of Cu.     

Poly(ethylene glycol)‐based amphiphilic model conetworks: Synthesis by RAFT polymerization and characterization

Poly(ethylene glycol) (PEG)‐containing quasi‐model amphiphilic polymer conetworks (APCNs) were prepared by reversible addition fragmentation chain transfer (RAFT) polymerization using α,ω‐bis(2‐cyanoprop‐2‐yl dithiobenzoate)‐PEG as a bifunctional RAFT macrochain transfer agent (macro‐CTA) and stepwise additions of a hydrophobic monomer and a crosslinker (crosslinker: macro‐CTA = 10:1, reaction time 24 h). Three different types of monomers, methyl methacrylate (MMA), n‐butyl acrylate and styrene, were employed as the hydrophobic monomers, whereas ethylene glycol dimethacrylate, ethylene glycol diacrylate and 1,4‐divinylbenzene served as the respective crosslinkers. PEG homopolymer hydrophilic quasi‐model networks were also prepared by RAFT‐polymerizing the three crosslinkers directly onto the two active ends of the PEG‐based macro‐CTA. From the three ABA triblock copolymers prepared, the MMA‐containing one was obtained at the highest polymerization yields. The crosslinking yields of the three ABA triblock copolymers with the corresponding crosslinkers were higher than those of the PEG‐based macro‐CTA with the same crosslinkers. The degrees of swelling (DSs) of all conetworks were measured in water and in tetrahydrofuran (THF). The DSs of the APCNs in THF were higher than those in water, whereas the reverse was true for the DSs of the hydrophilic homopolymer networks. Finally, the aqueous DSs of the APCNs were lower than those of the corresponding hydrophilic homopolymer networks. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 7556–7565, 2008     

Physical properties of poly(ethylene glycol) (PEG)-based resins for combinatorial solid phase organic chemistry: a comparison of PEG-cross-linked and PEG-grafted resins

Three series of poly(ethylene glycol) (PEG)-based polymers were synthesized and characterized with respect to their physical properties. Polyoxyethylene-polyoxypropylene (POEPOP), polyoxyethylene-polyoxetane (SPOCC), and polyoxyethylene-polystyrene (POEPS-3) were synthesized respectively by anion polymerization, cation polymerization, and radical polymerization. Both bulk and suspension modes were used to synthesize the polymers from derivatized PEG monomers (PEG 400, PEG 900, and PEG 1500). The three supports were compared with two commercially available PEG-grafted supports (TentaGel S OH, ArgoGel-OH) and two polystyrene supports (aminomethylated polystyrene [PS-NH2] and macroporous aminomethylated polystyrene [PLAMS]) with respect to their swelling properties, loading, NMR spectral quality, as well as solvent and reagent accessibility. Loadings of 0.3-0.7 mmol/g were obtained for the PEG-based resins. Swelling of the PEG-based resins was determined to be higher than that of the PEG-grafted resins and polystyrene supports. The PEG-based resins gave better resolved high-resolution NMR spectra than the PEG-grafted resins when examined by magic angle spinning nanoprobe (MAS) NMR spectroscopy. Moreover, fluorescence quenching of polymer bound 2-amino-benzoate by protonation with p-toluenesulfonic acid showed moderate to fast diffusion through the polymer depending on the solvent and the polymer matrix.     

松香基聚醚酯弹性体的制备及表征

通过松香与聚醚丙烯酸酯的Diels Alder加成产物与聚乙二醇、柠檬酸的缩聚反应,合成出松香基聚醚酯弹性体,产物采用红外、拉伸、DSC和TGA进行了表征。 TGA测试表明,松香基聚醚酯弹性体的10%热失重温度在300 ℃以上,拉伸测试表明,拉伸强度为0.26～0.62 MPa,断裂伸长率为338%～458%。     

The metal loading ability of beta-amyloid N-terminus: a combined potentiometric and spectroscopic study of copper(II) complexes with beta-amyloid(1-16), its short or mutated peptide fragments, and its polyethylene glycol (PEG)-ylated analogue

Alzheimer's disease (AD) is becoming a rapidly growing health problem, as it is one of the main causes of dementia in the elderly. Interestingly, copper(II) (together with zinc and iron) ions are accumulated in amyloid deposits, suggesting that metal binding to Abeta could be involved in AD pathogenesis. In Abeta, the metal binding is believed to occur within the N-terminal region encompassing the amino acid residues 1-16. In this work, potentiometric, spectroscopic (UV-vis, circular dichroism, and electron paramagnetic resonance), and electrospray ionization mass spectrometry (ESI-MS) approaches were used to investigate the copper(II) coordination features of a new polyethylene glycol (PEG)-conjugated Abeta peptide fragment encompassing the 1-16 amino acid residues of the N-terminal region (Abeta(1-16)PEG). The high water solubility of the resulting metal complexes allowed us to obtain a complete complex speciation at different metal-to-ligand ratios ranging from 1:1 to 4:1. Potentiometric and ESI-MS data indicate that Abeta(1-16)PEG is able to bind up to four copper(II) ions. Furthermore, in order to establish the coordination environment at each metal binding site, a series of shorter peptide fragments of Abeta, namely, Abeta(1-4), Abeta(1-6), AcAbeta(1-6), and AcAbeta(8-16)Y10A, were synthesized, each encompassing a potential copper(II) binding site. The complexation properties of these shorter peptides were also comparatively investigated by using the same experimental approach.     

二甲亚砜-二(4,4,4-三氟-1-(2-噻酚基)丁二酮-1,3)合铜单晶的ESR研究

由于过渡金属配合物的顺磁共振研究可以导出金属未成对电子的磁性质和金属离子与配体之间的成键信息。在对体系各种不同状态的研究中,以晶体的ESR数据最为准确可靠。β-二酮配合物一直是化学工作者开展研究的活跃领域。当中心金属离子为铜(Ⅱ)时,ESR     

聚(L-丙氨酸-co-羟丙-L-谷氨酰胺)无规共聚物的两亲性及其胶束行为研究

采用丙氨酸作为疏水聚合单体,谷氨酸作为亲水聚合单体,一步开环聚合反应,合成了具有两亲性的聚氨基酸无规共聚物.利用IR,1H-NMR等方法对所合成的聚合物进行了详细的表征,结果表明两种单体都能够按照投料比参加聚合反应生成无规共聚物.对比聚丙氨酸-聚羟丙谷氨酰胺嵌段共聚物,探讨了无规共聚物与嵌段共聚物在两亲性及结构性质上的差异和特点.研究表明,聚(L-丙氨酸-co-羟丙-L-谷氨酰胺)无规共聚物与嵌段共聚物一样,具有两亲性,在水溶液中也能够形成胶束,但胶束尺寸较嵌段共聚物要小,胶束形态也不像嵌段共聚物是规整的球形.实验发现,亲疏水单体的比例对胶束的形成有很大影响,P(A10-co-HPG40)所制得的胶束分散最为均匀.所形成的胶束以疏水的聚丙氨酸为内核,亲水的聚羟丙谷氨酰胺为外壳.     

超支化聚硅氧基硅烷的合成及其表征

基于线性聚硅氧烷在国防、能源和化工等领域的广泛应用,具有新颖拓扑结构和大量功能性端基的超支化聚硅氧烷引起了国内外科学工作者的广泛兴趣[1~7].到目前为止,主要是采用水解缩聚的方法合成超支化单体,在铂系催化剂存在下进行硅氢加成反应或者在碱催化剂存在下进行质子转移聚合制备超支化聚合物[8~12].然而,以上合成超支化聚硅氧烷的方法仍然存在一定的不足.例如,水解法步骤繁琐,通常在第一步反应结束后需要多次除水,并继续滴加单氯硅烷以得到完全取代的大单体;同时多官能度单体容易水解自缩聚,产生A2B4或A3B6等副产物,不仅不利于结构控…     

PEG／PED-g-CB化学敏电阻材料的制备及其气敏性能的研究

以不同分子量聚乙二醇(PEG)为基体，PEG接枝改性的炉法炭黑(PEG-g-CB)为导电裁流子，采用溶液分散工艺制得一种新鞭的气敏传感器材料。研究了PEG分子量对接枝率及对各种溶剂蒸气的响应性、响应灵敏度的影响；用透射电子显微镜(TEM)和紫外—可见分光光度计考察了两种炭黑粒子分散行为、袁面特性差异及其对响应重复性、稳定性的影响。结果表明，PEG／PEG-g-CB复合材料化学敏电阻体对其良溶剂蒸气如THF、氯仿、丙酮具有很强的响应性，其电阻值可提高到初始电阻的10^4～10^6倍。将这种材料再放入干燥空气中时，电阻又恢复到初始值；而对其不良溶剂如正己烷、甲苯几乎不响应。随PEG分子量的提高，响应灵敏度下降；响应的重复稳定性受炭黑粒子分散行为的影响，从聚合物溶胀行为及逾渗导电理论解释了实验结果。