聚膦腈-g-聚己内酯共聚物的合成与表征

通过三甲基碘硅烷与聚二(2-甲氧基乙氧基)膦腈侧链上的醚键反应后水解得到侧链含部分羟基的聚膦腈,然后利用聚膦腈的侧链羟基在异辛酸亚锡催化作用下,引发己内酯单体开环聚合制备了聚膦腈-g-聚己内酯共聚物.该共聚物中聚己内酯链段的接枝率和侧链长度可通过改变三甲基碘硅烷和己内酯单体的投料来控制.     

超支化聚合物结构和形貌的表征与分析

用固定化酶Novozyme435(NV435)催化2,2-二羟甲基丁酸(BHB)与ε-己内酯(ε-CL)开环缩聚得到端基中一端带有一个羧基,另一端带有多个羟基的超支化共聚酯。利用核磁共振分析(NMR)、傅立叶红外(FTIR)、凝胶渗透色谱仪(GPC)对超支化聚合物进行结构表征,用扫描电子显微镜(SEM)分析了聚合物的表面形貌。     

富勒烯衍生物引发的富勒烯末端封端聚己内酯的合成

利用带活性羟基的N-取代3,4-富勒烯吡咯烷作为引发剂,引发ε-己内酯开环聚合,制备了一种具有新型结构的富勒烯末端封端聚己内酯,通过核磁共振(1H NMR,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)等手段对产物进行了结构表征,并用热重(TG)分析和差示扫描量热(DSC)分析的方法进行了热学性能分析.结果表明,与聚己内酯相比产物热稳定性增加.     

由高效双键易位闭环反应合成环状聚ε-己内酯

研究了合成环状大分子的一种新方法,即借助活性开环聚合反应和高效双键易位闭环反应(RCMR)合成环状聚ε-己内酯.首先,ε-己内酯在环状引发剂2,2-二丁基-2-锡-1,3-二氧环庚烷(DSDOP)的作用下,进行活性开环聚合反应,获得双羟基封端的聚ε-己内酯(PCLOH);然后,在对甲苯磺酸、1,3-二环己基碳二亚胺(DCC)和4-二甲氨基吡啶(DMAP)的作用下,将PCLOH与3-丁烯酸反应转化为双烯丙基封端的聚ε-己内酯(allylPCL);在Grubbs催化剂(Cl2(Cy3)2Ru CHPh)的作用下,将allylPCL经RCMR环化成环状聚ε-己内酯,并采用SEC,NMR,TGA以及DSC等技术对聚合物的结构和热力学性能进行了表征,SEC和黏度表征结果显示环状聚ε-己内酯具有较小的动态力学体积,TGA和DSC表征结果显示环状聚ε-己内酯的热分解温度较其线型前体高13℃,环化的结果使其熔点和结晶度下降.结果表明allylPCL在较稀(2.5×10-5mol/L)体系中,借助Grubbs催化剂进行的RCMR分子内环化反应效率高,环化产物无需进一步分离提纯.     

新型改性聚己内酯型聚氨酯弹性体的合成及性能

用不同种类异氰酸酯[脂肪族六亚甲基二异氰酸酯(HDI)和脂环族异佛尔酮二异氰酸酯(IPDI)]对聚己内酯(PCL)进行改性,得到两端为羟基的异氰酸酯改性的PCL预聚体.将未改性和改性的PCL端羟基进行磷酸化后[磷酸化组分PCL210磷酸酯(A)、PCL205/HDI磷酸酯(B)和PCL205/IPDI磷酸酯(C)]与双官能度的环氧(1,4-丁二醇二缩水甘油醚,E)进行开环交联反应,得到生物相容且可降解的聚己内酯型聚氨酯弹性体材料(AE,BE和CE).聚己内酯型聚氨酶弹性体的力学性能、静态水接触角、体外降解/溶胀和细胞毒性测试结果表明,PCL异氰酸酯的改性有助于提高材料的强度、弹性、耐疲劳性和降解速率,同时未明显提高材料的细胞毒性.     

聚己内酯/聚缩水甘油醚两亲性超枝状大分子的合成及表征

通过简单的两步反应, 合成出新型超枝状聚己内酯/聚缩水甘油醚嵌段共聚物. 以月桂醇为引发剂, 通过开环聚合反应合成羟基封端的聚己内酯; 将聚己内酯进一步和萘钾反应, 得到基于己内酯的大分子引发剂; 引发缩水甘油醚的聚合, 最终形成聚己内酯/聚缩水甘油醚嵌段共聚物. 通过核磁共振氢谱、红外光谱和葡聚糖凝胶色谱对聚合物进行定性表征. 结果表明, 所得到的聚合物既具有聚己内酯的特征峰, 又有聚缩水甘油醚的特征峰, 通过核磁共振氢谱计算出二者在嵌段共聚物中的比例. 在这些聚合物骨架上存在大量的羟基末端基团, 葡聚糖凝胶色谱表征得到单峰, 进一步证明聚合物为嵌段共聚物. 相对于单纯的聚己内酯, 这种聚合物结构的突出优势在于其具有大量可修饰的高活性端基基团, 通过对端基基团的后修饰, 可实现各类配体及多种药物的偶联, 使这种新型材料有可能应用于多功能靶向药物传递.     

聚(苯乙烯-ε-己内酯)嵌段共聚物的研究

本文采用活性阴离子聚合方法合成聚(苯乙烯-ε-己内酯)嵌段共聚物。研究了聚合反应条件,并用GPC、柱上溶解分级及红外光谱进行表征。对产物进行结构分析,产物为聚(苯乙烯-ε-己内酯)嵌段共聚物,具有多相结构,是由无定形聚苯乙烯链段、无定形聚-ε-己内酯链段和结晶型聚-ε-己内酯链段组成的嵌段共聚物。对该嵌段共聚物的性能进行了测试。     

以高顺式聚丁二烯为软段的三嵌段共聚物的制备

从高顺式端羟基聚丁二烯(HTPB)出发,分别以ε-己内酯和苯乙烯为单体合成了2类以高顺式聚丁二烯为软段的三嵌段共聚物.以高顺式HTPB为大分子引发剂、辛酸亚锡为催化剂,引发ε-己内酯的开环聚合,合成了聚己内酯-b-聚丁二烯-b-聚己内酯三嵌段共聚物(CLBCL);通过高顺式HTPB末端羟基与2-溴代异丁酰溴(BBi B)间的酯化反应制备了ATRP大分子引发剂(Bi B-PB-Bi B),进而引发苯乙烯进行电子转移活化再生催化剂原子转移自由基聚合(ARGET ATRP)反应,合成了聚苯乙烯-b-聚丁二烯-b-聚苯乙烯三嵌段共聚物(SBS),反应具有较好的可控性,产物分子量分布较窄.通过红外光谱(FTIR)、核磁共振氢谱(1H-NMR)和碳谱(13CNMR)、热重分析(TGA)和示差扫描量热分析(DSC)等对所制备共聚物的结构和性能进行了测试表征.TGA曲线表明,提高聚己内酯链段的含量,可在一定程度上提高CLBCL共聚物的热稳定性;SBS共聚物的热分解过程表现为一个阶段,与HTPB相比,其热稳定性略有提高.从CLBCL共聚物的DSC曲线上可明显观察到聚丁二烯链段的玻璃化转变温度和聚己内酯链段的熔点;SBS共聚物具有2个玻璃化转变温度,为–104.1和102.4oC,分别对应于聚丁二烯链段和聚苯乙烯链段的玻璃化转变温度.     

聚己内酯接枝淀粉纳米晶的制备

通过异氰酸酯与端羟基聚己内酯反应制备端异氰酸酯基预聚体,再接枝到淀粉纳米晶表面,制备了端基分子量可控的聚己内酯接枝淀粉纳米晶。分别用FTIR和1H NMR对所制备的聚己内酯接枝淀粉纳米晶进行表征,结果表明,有少量聚己内酯接枝到淀粉纳米晶表面。XRD结果表明,接枝了少量聚己内酯后的淀粉纳米晶的晶型和结晶度与未接枝的淀粉纳米晶基本一致。聚己内酯接枝淀粉纳米晶的熔融温度由115℃左右提高到122℃左右,并且温度范围变宽。浸润性实验表明,聚己内酯接枝淀粉纳米晶与水不浸润,其表面已具有疏水性。聚己内酯仅接枝在淀粉纳米晶的表面,改善了淀粉纳米晶表面的疏水性能和与聚酯类聚合物的界面相容性。聚己内酯接枝淀粉纳米晶有望用于可降解聚酯类高分子材料,如聚乳酸(PLA)、聚己内酯(PCL)、聚丁二酸丁二醇酯(PBS)等,改善其力学性能和生物降解性能等。     

官能团化聚己内酯的制备及其生物应用

聚己内酯(PCL)是一种疏水的、半结晶的、可降解的脂肪族聚合物,其具有良好的生物相容性、药物透过性和机械性能,在药物缓释和组织工程领域得到了广泛的关注。由于其结晶性强,亲水性差,生物降解速度慢,限制了其在生物医用领域更广泛的应用。聚己内酯的官能团化可实现对聚酯材料亲疏水性、降解速率等物化性质的调节,同时,活性官能团的引入便于对PCL的进一步化学修饰,有利于拓宽聚己内酯类材料的生物医用领域。本文详细介绍在聚己内酯骨架引入侧基官能团的化学方法,并简要阐述了官能团化聚己内酯在生物医用材料领域的应用。     

Molecular parameters of hyperbranched polymers made by self‐condensing vinyl polymerization of macroinimers

The molecular weight averages and the degree of branching, DB, of a hyperbranched polymer obtained by self‐condensing vinyl polymerization (SCVP) of a macroinimer A‐(m)_γ‐B* is calculated by modifying the existing equations for SCVP. The polydispersity is lowered by a factor (γ + 1), where γ is the degree of polymerization of the macroinimer. DB decreases with γ, however, at full conversion the DB of the polymacroinimer is approximately 60% higher than expected from the “dilution” of an AB* inimer with linear m units. This is the result of the existence of a new kind of branched units. The structure of polymacroinimers is similar to the pattern of a highly branched copolymer obtained by self‐condensing vinyl copolymerization. However, the polydispersity index and the DB of these two processes are different, for a given molecular weight the polydispersity and the DB of the macroinimer is lower than the corresponding parameters for SCVCP at the same value of γ.     

支化PEG-b-PCL嵌段共聚合物的合成

以聚乙二醇甲基丙烯酸酯(PEGMA)为大分子引发剂进行ε-己内酯的酶催化开环聚合, 合成出嵌段共聚物, 然后将其转化成大分子引发剂型单体(Macroinimer), 最后通过原子转移自由基聚合(ATRP)制备出一种新型结构的嵌段型支化聚合物.     

Branched Azobenzene Side‐Chain Liquid‐Crystalline Copolymers Obtained by Self‐Condensing ATR Copolymerization

Summary: The one step synthesis of a series of branched azobenzene side‐chain liquid‐crystalline copolymers by the self‐condensing vinyl copolymerization (SCVCP) of a methyl acrylic AB* inimer, 2‐(2‐bromoisobutyryloxy)ethyl methacrylate (BIEM), with the monomer 6‐(4‐methoxy‐azobenzene‐4′‐oxy)hexyl methacrylate (M), by atom transfer radical polymerization (ATRP) in the presence of CuBr/N,N,N′,N′,N″‐pentamethyldiethylenetriamine as a catalyst system, and in chlorobenzene solvent, is reported. The degree of branching (DB), and the molecular weights and polydispersities of the resultant polymers were determined by NMR spectroscopy and size exclusion chromatography, respectively. The phase behaviors of the branched copolymers were characterized by differential scanning calorimetry (DSC) and thermal polarized optical microscopy (POM). The degree of branching of the branched copolymers could be controlled by the comonomer ratio in the feed and influenced their liquid‐crystal properties. Liquid‐crystal properties were not exhibited when the comonomer ratio was low. Comonomer ratios greater than 8 gave polymers with a lower number of branches, which exhibited both a smectic and a nematic phase.

A polarized optical micrograph of the smectic phase texture of a polymer synthesized here with a higher comonomer feed ratio (magnification × 400).     

A novel macroinimer of polyethylene oxide: synthesis of hyper branched networks by photoinduced H-abstraction process

A novel poly(ethylene oxide) macroinimer (PEO-macronimer) possesing methacryloyl and tertiary amino end groups was prepared by ring-opening polymerization of ethylene oxide initiated by potassium 2-methylaminoethoxide and termination of living ends of PEO with methacryloyl chloride. NMR analysis showed that the macronimer contains equal amount of amino and methacrolyl groups indicating efficient initiation and termination processes. The dimethylamine end group in conjunction with benzophenone under UV irradiation produced ternary amine methylene radicals via H-abstraction mechanism which initiates the polymerization. Photopolymerization in solutions at high macroinimer concentration or in films resulted in the formation of insoluble networks. The crosslinked polymers exhibit high swelling capacity in organic solvents and water due to the hyperbranched nature.     

The dispersion polymerization of unsaturated monomers initiated by the macromonomeric initiator

The dispersion polymerizations of styrene (St) and methyl methacrylate (MMA) initiated by poly(oxyethylene) macroinimer (PEO-MIM) in ethanol/water were investigated at 50, 60 and 80°C. The polymerisation rate vs. conversion dependence was described by with a maxim at the beginning of polymerisation. Polymerization was faster with MMA than with St. The limiting conversion was inversely proportional to temperature and was much more pronounced with St. The rate of polymerization increased with temperature. The overall initial activation energy increased with conversion and reached value ca. 25 kJ.mol⁻¹ for MMA and 50 kJ.mol⁻¹ for styrene at ca. 60% conversion. The particle size was observed to decrease with increasing the macroinimer concentration. The polymer dispersions were unstable and a large amount of coagulum appeared during the polymerisation especially in the styrene-containing reaction system.     

Synthesis of a novel macroinimer based on thiophene and poly(ε‐caprolactone) and its use in electrochromic device application

Synthesis of a novel macroinimer comprising poly(ε‐caprolactone) (PCL) and thiophene (Th) and its use in electrochromic device (ECD) application have been reported. First, a novel Th monomer ( 5 ) with miktofuntional initiator groups (primary hydroxyl and tertiary bromide at the third position of the thiophene ring) was synthesized in a four‐step reaction sequence. Density functional theory‐predicted bond lengths, angles, and vibrations of 5 were in good agreement with available experimental vibrational spectra. Subsequently, ring‐opening polymerization of ε‐caprolactone (ε‐CL) was carried out in bulk using 5 as the initiator and tin(II) 2‐ethylhexanoate (Sn(Oct)₂) as the catalyst at 115 °C, which led to α‐thiophene end‐capped PCL macroinimer (PCL‐Th). Furthermore, PCL‐Th macroinimer was used in electrochemical copolymerization with pyrrole (Py) and Th. PCL‐Th/PTh copolymer film synthesized on indium tin oxide‐coated glass slide showed electrochromic behavior. Optical analyses of the PCL‐Th/PTh copolymer film indicated that the copolymer film was suitable to be used as an anodically coloring material for ECD applications. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Control of electron transfer in supramolecular systems

The fluorescence quantum yield of zinc porphyrin (ZnP) covalently linked to 9,10-bis(phenylethynyl)anthracene (AB) is strongly dependent upon the solvent properties. The bichromophoric system ZnP-AB exhibits 'normal' zinc porphyrin fluorescence in solvents that cannot coordinate to the central zinc atom. In contrast, if a Lewis base, such as pyridine, is added to a sufficiently polar solvent, the fluorescence is significantly quenched. Picosecond transient absorption measurements, in conjunction with fluorescence quenching and cyclic voltammetric measurements, suggest that the quenching mechanism is intramolecular electron transfer from ZnP to AB. The charge separated state. ZnP*+-AB*-, has a lifetime of not more than 220 ps before recombining. If a secondary electron acceptor, iron(III) porphyrin (FeP), is covalently connected to the AB unit, a second electron transfer from AB*- to FeP occurs and the charge separated state, ZnP*+-AB-FeP*-, has a lifetime of at least 5 ns. This demonstrates that electron transfer might be sensitively tuned (switched on) by specific solvent effects.     

Hyperbranched fluorocopolymers by atom transfer radical self‐condensing vinyl copolymerization

Hyperbranched fluorocopolymers were synthesized by the atom transfer radical self‐condensing vinyl copolymerization (ATR–SCVCP) of an inimer, either p‐chloromethylstyrene (CMS) or p‐bromomethylstyrene (BMS), with 2,3,4,5,6‐pentafluorostyrene (PFS), with 2,2′‐bipyridine together with CuCl or CuBr as the ligand/catalyst system. The reaction conditions were studied to provide for control over the copolymer compositions, molecular weights, degrees of branching, and properties, as characterized by ¹H, ¹³C, and ¹⁹F NMR spectroscopy, gel permeation chromatography, elemental analysis, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and solubility tests. Copolymers having number‐average molecular weights from 2.9 to 260 kDa and polydispersities (weight‐average molecular weight/number‐average molecular weight) from 1.8 to 4.8 were obtained. The molar fractions of PFS units increased with increases in the feed ratio of PFS to the inimer. The degrees of branching were typically about 30% with the feed of 1.0 or 2.0 equiv of PFS with respect to the inimer, although slight variations could be achieved through the variation of the inimer composition. Under similar reaction conditions with CuCl as the catalyst, ATR–SCVCP of BMS with PFS led to higher degrees of branching than ATR–SCVCP of CMS with PFS. Solubility tests indicated that the polymers prepared under conditions that avoided extensive biradical coupling were soluble in a broad range of organic solvents. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 4754–4770, 2005     

Intramolecular NH/pi complexes of 2-allylaniline derivatives in the ground and excited states

The photochemical and photophysical properties of three 8-allyl-1,2,3,4-tetrahydroquinolines (1a-c) have been studied. These compounds exhibit a 2-allylaniline-like photochemical behavior, undergoing photocyclization to lilolidines (3a-c). The absorption, emission, and excitation spectra of 1a-c, employing convenient model compounds for comparison, demonstrate the formation of a NH/pi intramolecular ground-state complex (AB). This species can absorb light at long wavelengths (330-340 nm), giving rise to the corresponding excited complex AB*. Emission from AB* is red-shifted (420 nm) with respect to that observed when the monomer A is excited (lambda(exc) = 300 nm). These experimental results have been rationalized by means of density-functional theory calculations.     

Photo-Induced Self-assembly of Copolymer-Capped Nanoparticles into Colloidal Molecules

Colloidal molecules (CMs) are precisely defined assemblies of nanoparticles (NPs) that mimic the structure of real molecules, but externally programming the precise self-assembly of CMs is still challenging. In this work, we show that the photo-induced self-assembly of complementary copolymer-capped binary NPs can be precisely controlled to form clustered AB _x or linear ( AB ) _y CMs at high yield (x is the coordination number of NP- B s, and y is the repeating unit number of AB clusters). Under UV light irradiation, photolabile p-methoxyphenacyl groups of copolymers on NP- A *s are converted to carboxyl groups (NP- A ), which react with tertiary amines of copolymers on NP- B to trigger the directional NP bonding. The x value of AB _x can be precisely controlled between 1 and 3 by varying the irradiation duration and hence the amount of carboxyl groups generated on NP- A s. Moreover, when NP- A * and NP- B are irradiated after mixing, the assembly process generates AB clusters or linear ( AB ) _y structures with alternating sequence of the binary NPs. This assembly approach offers a simple yet non-invasive way to externally regulate the formation of various CMs on demand without the need of redesigning the surface chemistry of NPs for use in drug delivery, diagnostics, optoelectronics, and plasmonic devices.