聚乙二醇/聚己内酯两亲性三嵌段共聚物纳米胶束

研究了制备聚乙二醇-b-聚己内酯-b-聚乙二醇两亲性三嵌段共聚物(PECL)纳米胶束的各种影响因素,发现PECL纳米胶束的粒径受制备方法的影响较大,且随着PECL的相对分子质量和混合溶剂中二氯甲烷用量的增大而增大。PECL的临界聚集浓度小于4×10-6mol/L,随着共聚物相对分子质量的增大而减小,纳米分散液的临界聚沉浓度随着PECL中PCL相对分子质量的增加而减小,分散液稳定性下降。     

DNA Hairpin Stabilization on a Hydrophobic Surface

DNA hybridization in the vicinity of surfaces is a fundamental process for self‐assembled nanoarrays, nanocrystal superlattices, and biosensors. It is widely recognized that solid surfaces alter molecular forces governing hybridization relative to a bulk solution, and these effects can either favor or disfavor the hybridized state depending on the specific sequence and surface. Results presented here provide new insights into the dynamics of DNA hairpin‐coil conformational transitions in the vicinity of hydrophilic oligo(ethylene glycol) (OEG) and hydrophobic trimethylsilane (TMS) surfaces. Single‐molecule methods are used to observe the forward and reverse hybridization hairpin‐coil transition of adsorbed species while simultaneously measuring molecular surface diffusion in order to gain insight into surface interactions with individual DNA bases. At least 35 000 individual molecular trajectories are observed on each type of surface. It is found that unfolding slows and the folding rate increases on TMS relative to OEG, despite stronger attractions between TMS and unpaired nucleobases. These rate differences lead to near‐complete hairpin formation on hydrophobic TMS and significant unfolding on hydrophilic OEG, resulting in the surprising conclusion that hydrophobic surface coatings are preferable for nanotechnology applications that rely on DNA hybridization near surfaces.     

聚酯纤维的附生结晶法改善纤维的表面浸润性

将聚对苯二甲酸乙二醇酯(PET)纤维置入过冷态的聚乙二醇(PEG)和聚己二酸丁二酯(PBA)熔体,制备了PET纤维/PEG基体和PET纤维/PBA基体复合体系。使用偏光显微镜和原子力显微镜研究了这两种异质复合体系的界面结晶形态,利用接触角测量仪测量了附生结晶法改性前后PET纤维织物的接触角。结果表明,纤维置入温度和结晶等条件决定附生体系的横穿晶体形态结构,选取合适的树脂并采用附生结晶的方法可明显改善PET纤维织物的表面浸润性,并有望改善PET纤维增强复合材料内部的界面结构。     

聚乳酸的增塑改性

采用溶液共混法,以聚乙二醇(PEG)、邻苯二甲酸二丁酯(DBP)、邻苯二甲酸二辛酯(DOP)作为增塑剂,对聚左旋乳酸(PLA)进行增塑改性.用综合热分析仪对改性PLA的热性能进行了表征.讨论了不同的增塑剂及其用量对改性PLA性能的影响:当增塑剂的含量增加时,改性PLA的强度下降,伸长率增加,并逐渐由脆性向韧性转变;玻璃化转变温度(Tg)和熔点(Tm)下降.当增塑剂的质量比≤20%时,共混物各组分间有较好的相容性.PEG400改性的PLA效果较好.     

星形聚乙二醇-聚乳酸嵌段共聚物的合成与表征

以不同臂数和分子量的星型聚乙二醇(sPEG)和L-丙交酯为原料,采用开环聚合法合成了以星型聚乙二醇为内部嵌段、聚L-乳酸为外部嵌段的多臂星形聚乙二醇-聚乳酸嵌段共聚物(sPEG-b-PLLA)。研究了sPEG的臂数、分子量及L-丙交酯/sPEG投料比等参数对产物结构与性能的影响。并分别用红外光谱(FT-IR)、核磁共振(1H-NMR)、凝胶渗透色谱(GPC)、差示扫描量热(DSC)对产物进行了表征,证实所合成的嵌段共聚物具有预期的结构。结果表明,sPEG-b-PLLA为结晶性聚合物,且表现出与PLLA相似的晶型,随着PLLA链段的增加,产物的结晶度也呈增大的趋势;与PLLA相比,sPEG-b-PLLA的接触角随着PEG链段的增多而增大,表明其亲水性明显改善。     

聚乙二醇及其络合物的^13C CP／MAS谱

报导了聚乙二醇及其络合物的~(13)C CP/MAS谱并测量了质子旋转坐标系自旋-晶格弛豫时间,结果反映了络合物的相结构或分子堆积结构不同于聚乙二醇。     

硫酸钙催化环氧乙烷的聚合反应

用硫酸钙催化环氧乙烷聚合得到了一种中高分子量的聚乙二醇。用红外、核磁等仪器对产物进行了表征。通过测定反应体系压降速率定性描述了聚合速率,研究发现,聚合速率与单体浓度呈二次关系,与催化剂用量呈一次关系;该反应具有准活性聚合特点。     

聚乙二醇刷型聚合物在聚砜膜上的光化接枝

对在聚砜薄膜上接枝的聚乙二醇的形貌做了大量研究,探讨了在透明平整的无孔聚砜薄膜上接枝刷型聚乙二醇的条件。首先制作出了透明且光滑平整的无孔聚砜薄膜,然后以对叠氮苯甲酸为光敏剂,在λ=365 nm紫外光的辐照下,用二步法将聚乙二醇接枝在聚砜膜表面,通过X射线-光电子能谱分析、原子力学显微镜及椭圆偏振仪等测试手段,对接枝前后聚砜膜表面形貌进行了表征,证明接枝的聚乙二醇层呈刷状。     

Tunable Assembly of Gold Nanoparticles on Nanopatterned Poly(ethylene glycol) Brushes

The organization of metallic nanoparticles (NPs) into ordered arrays on nanopatterned surfaces is an enabling process to fabricate devices and study the properties of the particles. Tailoring the interaction between NPs and nanopatterns is a necessity to gain a high level of control in this process. Here, nanopatterned poly(ethylene glycol) (PEG) brushes are presented as a platform for the organization of Au NPs on surfaces. The binding of citrate‐stabilized Au NPs to the PEG brushes depends on the size of the particles and molecular weight of the brushes: the density of NPs immobilized on the nanopatterns of PEG brushes increases with decreasing the diameter of the particles and increasing the chain length of the brushes. The key aspect of the process is to pattern PEG brushes with high resolution and chemical contrast to provide controllable and specific interaction between Au NPs and nanopatterns at a single particle resolution. The modulation of the number (0–4) of Au NPs (e.g., 30 nm) per patterned feature with a high level of accuracy and the generation of patterned heterostructures that consist of two different sizes (e.g., 40 and 20 nm) of particles constitute two examples showing the capabilities of the presented platform.     

透明质酸/胶原蛋白/聚乙二醇复合水凝胶的研究

针对透明质酸、胶原蛋白水凝胶力学性能差的问题,采用两步交联法将透明质酸、胶原蛋白与聚乙二醇双丙烯酸酯制备成一种兼具生物相容性和高强度的复合水凝胶。研究制备了具有相同胶原蛋白和聚乙二醇双丙烯酸酯质量分数,不同透明质酸质量分数的水凝胶,从微观结构和力学强度调控了复合水凝胶的理化性能,并用L-赖氨酸对复合凝胶进行改性。SEM结果表明,三元复合水凝胶具有蜂窝状的内部结构,孔径范围在80~180μm,赖氨酸浓度达40 mmol/L时,水凝胶的压缩模量达414 k Pa,是改性前模量的19倍。细胞毒性和体内植入实验表明该水凝胶浸提环境对细胞生长无明显抑制作用,产生较低的免疫排斥反应,有望用于软骨等组织的修复。     

乙二醇掺杂对PVA/PEDOT∶PSS导电纤维结构和性能的影响

通过湿法纺丝制备聚乙烯醇(PVA)/聚3,4-乙撑二氧噻吩:聚对苯乙烯磺酸(PEDOT∶PSS)共混纤维,为改善共混纤维的导电性能,在PVA/PEDOT∶PSS共混纺丝液中加入乙二醇,制备出掺杂不同乙二醇含量的共混纤维。探究了乙二醇掺杂对PVA/PEDOT∶PSS共混纤维结构和性能的影响,并分析机理。采用红外光谱、原子力显微镜、显微共聚焦激光拉曼光谱仪,高阻计和电子单纤维强力仪对共混纤维的结构和性能进行测试表征。结果表明,随着乙二醇掺杂量的增加,共混纤维电导率逐渐增加,最高达到15.9 S/cm;拉曼光谱显示乙二醇掺杂使PEDOT主链发生苯醌转变,PEDOT的主要特征峰发生红移;红外光谱显示掺杂不改变共混纤维的化学组成;原子力显微镜结果显示随着乙二醇掺杂质量分数的提高,PEDOT与过剩PSS发生相分离,共混纤维表面粗糙度增加;此外,随着乙二醇掺杂质量分数的提高,共混纤维的拉伸强度逐渐升高,断裂伸长逐渐降低。     

Engineering of poly(ethylene glycol) chain-tethered surfaces to obtain high-performance bionanoparticles

Abstract

A poly(ethylene glycol)-b-poly[2-(N,N-dimethylamino)ethyl methacrylate] block copolymer possessing a reactive acetal group at the end of the poly(ethylene glycol) (PEG) chain, that is, acetal-PEG-b-PAMA, was synthesized by a proprietary polymerization technique. Gold nanoparticles (GNPs) were prepared using the thus-synthesized acetal-PEG-b-PAMA block copolymer. The PEG-b-PAMA not only acted as a reducing agent of aurate ions but also attached to the nanoparticle surface. The GNPs obtained had controlled sizes and narrow size distributions. They also showed high dispersion stability owing to the presence of PEG tethering chains on the surface. The same strategy should also be applicable to the fabrication of semiconductor quantum dots and inorganic porous nanoparticles. The preparation of nanoparticles in situ, i.e. in the presence of acetal-PEG-b-PAMA, gave the most densely packed polymer layer on the nanoparticle surface; this was not observed when coating preformed nanoparticles. PEG/polyamine block copolymer was more functional on the metal surface than PEG/polyamine graft copolymer, as confirmed by angle-dependent x-ray photoelectron spectroscopy. We successfully solubilized the C₆₀ fullerene into aqueous media using acetal-PEG-b-PAMA. A C₆₀/acetal-PEG-b-PAMA complex with a size below 5 nm was obtained by dialysis. The preparation and characterization of these materials are described in this review.     

聚乙二醇二丙烯酸酯齐聚物的合成及其红外激光固化性能研究

使用3种方法合成了具有不同分子量的聚乙二醇二丙烯酸酯（PEGDA）齐聚物,包括：聚乙二醇（PEG）与丙烯酸反应,聚乙二醇与丙烯酰氯反应,聚乙二醇钠与丙烯酰氯反应,并在此基础上对3种合成方法进行比较。研究了聚乙二醇二丙烯酸酯齐聚物的红外激光固化反应,利用红外分析测定双键转化率,发现随着齐聚物分子量增大,激光固化后的双键转化率有所上升。     

Studies on epoxy-polysulfone blend

Synthesis of carboxyl terminated poly (ethylene glycol adipate) (CTPA) and amine terminated poly(amide sulfone) (PS) based on the CTPA and an aromatic diamine has been described. The products were characterized by¹³C NMR and IR spectroscopic analysis, nonaqueous titration, viscosity measurement and solubility characteristic studies. Effect of incorporation of the developed PS on epoxy matrix was studied. Epoxy-PS blends were evaluated with respect to their thermal and dynamic mechanical properties. Paper presented at the poster session of MRSI AGM VI, Kharagpur, 1995     

Exploring the formation of focal adhesions on patterned surfaces using super-resolution imaging

The formation of focal adhesions on various sizes of fibronectin patterns, ranging from 200 μm to 250 nm, was systematically investigated by total internal reflection fluorescence microscopy and super-resolution imaging. It was found that cells adhered to and spread on these micro/nanopatterns, forming focal adhesions. On a micrometer scale the shape of the focal adhesions was elongated. However, on the nanometer scale, the shape of focal adhesions became dotlike. To further explore the distribution of focal adhesion proteins formed on surfaces, a localization-based super-resolution imaging technique was employed in order to determine the position and density of vinculin proteins. A characteristic distance of 50 nm was found between vinculin molecules in the focal adhesions, which did not depend on the size of the fibronectin nanopatterns. This distance was found to be crucial for the formation of focal adhesions. In addition, the density of vinculin at the focal adhesions formed on the nanopatterns increased as the pattern size decreased. The density of the protein was found to be 425 ± 247, 584 ± 302, and 703 ± 305 proteins μm(-2) on the 600, 400, and 250 nm fibronectin patterns respectively. Whereas 226 ± 77 proteins μm(-2) was measured for the matured focal adhesions on homogeneous fibronectin coated substrates. The increase in vinculin density implies that an increase in mechanical load was applied to the focal adhesions formed on the smaller nanopatterns.     

聚乙二醇对合成无定形磷酸钙的影响

采用聚乙二醇(PEG)先与钙反应后,再与磷源溶液反应,在低温环境中制得无定形磷酸钙.借助XRD分析讨论了PEG∶CaCl₂配比及PEG分子量与形成无定形磷酸钙之间的关系,实验结果表明,PEG∶CaCl₂配比为1∶1和PEG分子量为10000是形成稳定无定形磷酸钙的最佳条件.其PEG稳定无定形磷酸钙的作用可理解为:在合成过程中PEG易存在于无定形磷酸钙Ca₉(PO₄)₆团簇之间和吸附在无定形磷酸钙颗粒周围,有效地阻止了无定形磷酸钙向晶态的转变.     

网状聚合物冠醚的压电性能研究

合成了３种网状聚合物冠醚;聚乙二醇双环氧丙基醚,聚一缩二乙二醇双环氧丙基醚和聚二缩三乙二醇双环氧丙基醚。实验表明,ＮＰＣＥ与金属盐络合后具有良好的压电性能,并络合金属直 多,了子价态越高和阴离子体积越小,则压电性能越好,电导率越高。