Synthesis of azidourethane block copolymers

Methods of structuring thermoreversible urethane block copolymers on the basis 3,3-bis-(azidomethyl)oxetane (BAMO) and 3-(azidomethyl)-3-methyloxetane (AMMO) were developed for the first time. Type (AB)_n copolymers of BAMO and AMMO have an amorphous crystalline structure but differ from the type B(AB)_n copolymers in that they contain less crystal phase and have a higher glass transition temperature and better physicomechanical properties.     

Spiro(benzoxasilole) catalyzed polymerization of oxetane derivatives

A spiro(benzoxasilole) catalyst, 3,3,3′,3′-tetrakis(trifluoromethyl)-1,1′-(3H,3H′)-spirobis(1,2-benzoxasilole) was used to polymerize 3,3-R,R′-oxetanes: BEMO (R, R′ = ethoxymethyl), AMMO (R = azidomethyl, R′ = methyl), NMMO (R = nitratomethyl, R′ = methyl), BAMO (R, R′ = azidomethyl), and BCMO (R, R′ = chloromethyl) with descending rates in this order. ³¹P-NMR of polymerization mixtures quenched using Bu₃P are consistent with an oxonium ion propagating species. Water is not a cocatalyst because it increases the induction period which is not eliminated by the proton trap 2,6-di-t-bu-tylpyridine. The propagating chains were terminated by transfer with the ether oxygen of the polymer either intermolecularly or intramolecularly. The index of propagation to chain transfer, Kk_ik_p/k_tr, varies over more than three orders of magnitude for BEMO > AMMO > NMMO > BAMO. However, k_p/k_tr for the four monomers differ by less than a factor of five indicating the same factors are affecting propagation and chain transfer. Addition of benzyl alcohol and propandiol produced poly(BEMO) having one and two hydroxyl termini, respectively. These telechelic polymers can be used to synthesize linear triblock or multiblock copolymers of oxetane derivatives. © 1992 John Wiley & Sons, Inc.     

Triblock copolymers based on cyclic ethers: Preparation and properties of tetrahydrofuran and 3,3-bis(azidomethyl) oxetane triblock copolymers

Novel energetic thermoplastic elastomers (TPEs) based on tetrahydrofuran (THF) and 3,3-bis (azidomethyl) oxetane (BAMO) were prepared in this present study by cationic living polymerization. A bifunctional catalyst, triflic anhydride [(CF₃SO₂)₂)O] was selected to be an initiator for the polymerization THF and BAMO. The resulting polymers were characterized by IR, NMR, and DSC, which demonstrated that triblock copolymers with A-B-A type were formed. The polymers were indicated from thermogravimetric analysis (TGA) to have decomposed at approximately 243°C. The decomposition enthalpies were determined by DSC. These enthalpies were varied with the poly-BAMO contents of the copolymers. The synthesized polymers exhibited relatively good mechanical properties and thermoplastic characteristics at room temperature. © 1994 John Wiley & Sons, Inc.     

Studies on the polymerization mechanism of 3-nitratomethyl-3′-methyloxetane and 3-azidomethyl-3′-methyloxetane and the synthesis of their respective triblock copolymers with tetrahydrofuran

Novel energetic oxetane derivatives, 3-nitratomethyl-3′-methyloxetane (NMMO) and 3-azidomethyl-3′-methyloxetane (AMMO), were used as monomers in a triflic anhydride [(CF₃SO₂)₂O] initiating polymerization system. The “living cationic” characteristics of the polymerization were investigated and confirmed via a ¹⁹F NMR technique. This living polymerization system was, thus, utilized in the synthesis of well-defined block copolymers. Novel polymers of the A—B—A— type with various molecular weights (M?_w = 14320–40660) and low polydispersity indexes (PDI = 1.11–1.29) were obtained. Two glass transition temperatures (T_g) near the respective T_gs of the homopolymers were found in the DSC thermograms of the block copolymers. The THF/AMMO copolymers were shown to possess higher thermal stability compared to THF/NMMO copolymers from thermogravimetric analysis (TGA). © 1995 John Wiley & Sons, Inc.     

RDX/AMMO推进剂的分子动力学

Molecular dynamics simulations have been performed to investigate well-known ener-getic material cyclotrimethylene trinitramine (RDX) crystal, 3-azidomethyl-3-methyloxetane (AMMO) and RDX/AMMO propellant. The results show that the binding energies on differ-ent crystalline surface of RDX changes in the order of (010)>(100)>(001). The interactions between RDX and AMMO have been analyzed by means of pair correlation functions. The mechanical properties of RDX/AMMO propellant, i.e. elastic coefficients, modulus, Cauchypressure, and Poisson's ratio, etc., have been obtained. It is found that mechanical properties are effectively improved by adding some amounts of AMMO polymers, and the overall effect of AMMO on three crystalline surfaces of RDX changes in the order of (100)>(010)>(001). The energetic properties of RDX/AMMO propellant have also been calculated and the results show that compared with the pure RDX crystal, the standard theoretical specific impulse of RDX/AMMO propellant decrease, but they are still superior to those of double base propellant.     

RDX/BAMO推进剂结合能、力学性质和能量性能的分子动力学模拟

利用分子动力学方法研究了著名的含能材料环三亚甲基三硝胺(RDX)、3,3′-双-(叠氮甲基)-氧杂环丁烷(BAMO)和RDX/BAMO推进剂. 结果表明, BAMO与RDX(010)面之间分子相互作用最强, 其次是(100)和(001)面. 以对相关函数g(r)描述了RDX和BAMO之间的相互作用. 计算了RDX/BAMO推进剂的弹性系数、模量、柯西压、泊松比等性能. 结果表明, BAMO的加入能够改善RDX的弹性力学性能, 相对改善效应的顺序为(100)>(001)>(010). RDX/BAMO推进剂的能量性能结果显示, BAMO的加入降低了RDX的比冲, 但仍高于著名的双基推进剂的比冲.     

3,3'-双叠氮甲基环氧丁烷-3-叠氮甲基-3'-甲基环氧丁烷无规共聚物的合成与结构表征

以1,4-丁二醇/三氟化硼乙醚为引发体系, 利用阳离子开环共聚合方法合成了3,3'-双叠氮甲基环氧丁烷(BAMO)与3-叠氮甲基-3'-甲基环氧丁烷(AMMO)的无规共聚物, 探讨了以Lewis酸为催化剂时活性链端与活性单体相互竞争的聚合反应机理. 同时根据GPC结果分析了聚合反应温度对产物分子量和分子量分布的影响. 结果表明, 在15 ℃时产物分子量可控且分布较窄. 通过1H NMR和13C NMR对无规共聚物的共聚组成及微观序列结构进行了表征, 结果表明, 共聚组成中两单体的摩尔比接近于1:1, 与投料比一致; 交替度接近50%, BAMO与AMMO链段的平均序列长度为2, 其结构单元呈随机分布的状态.     

Thermal degradation of aged polytetrahydrofuran and its copolymers with 3-azidomethyl-3′-methyloxetane and 3-nitratomethyl-3′-methyloxetane by thermogravimetry

The thermal decomposition behavior of the aged tetrahydrofuran copolymers with 3-azidomethyl-3′-methyloxetane (AMMO) or 3-nitratomethyl-3′-methyloxetane (NMMO) were studied by thermogravimetry and evolved gas analysis, and compared with aged polytetrahydrofuran (poly-THF) The thermal stability decreased in the order poly-THF > poly-AMMO-THF-AMMO > poly-NMMO-THF-NMMO, whereas the range of temperature for decomposition increased in the order poly-THF < poly-AMMO-THF-AMMO < poly-NMMO-THF-NMMO. The apparent activation energies of the degradation for polymers with ageing, calculated by the Ozawa method, were smaller than that without ageing. © 1996 John Wiley & Sons, Inc.     

Crystallization behavior of poly(3,3-bisethoxymethyl oxetane) and poly(3,3-bisazidomethyl oxetane)

Two crystal modifications have been found for poly(3,3-bisethoxymethyl oxetane) [poly- (BEMO)] by wide-angle x-ray powder diffraction and differential scanning calorimetry, while only one modification has been found for poly(3,3-bisazidomethyl oxetane) [poly(BAMO)]. Melting temperatures for the two polymers were nearly the same, varying from about 70 to about 90°C depending on the thermal treatment; higher crystallization temperatures resulted in higher melting temperatures. The equilibrium melting temperature T was found to be 125 and 128°C for poly(BEMO) and poly(BAMO), respectively, by using the Hoffman-Weeks extrapolation procedure. Measurement of the melting-point depression of Poly(BEMO) and poly(BAMO) in dibutyl phthalate yielded enthalpy of fusion values of 2.25 and 12.8 kcal/mol, respectively. The percent crystallinity for poly(BEMO) and poly(BAMO), respectively, was calculated to be 55-60 and 13-30% based on DSC and x-ray analysis.     

含聚二甲基硅氧烷侧链的丙烯酸酯共聚物的研究

采用含活性基团的聚二甲基硅氧烷与丙烯酸酯进行自由基共聚合，合成了自聚二甲基硅氧烷侧链的丙烯酸酯共聚物。采用ＩＲ，＾１Ｈ－ＮＭＲ，ＧＰＣ等分析方法对共聚物结构和组成进行了表征。通过接触角和Ｘ－射线光电子能谱对共聚物的表面性能和表面组成进行了研究，并通过粘接性能和破坏面形貌对共聚物与金属铝材和加成型硅橡胶的粘接性进行了探讨。     

Dynamic rheological behaviors of metallocene-based ethylene-butene copolymers and their blends with low-density polyethylene

The dynamic rheological properties of three metallocene-based ethylene-butene copolymers were examined and were compared with those of some conventional ethylene-butene copolymers and of a low density polyethylene (LDPE). Compared with the conventional ethylene copolymers, the metallocene-based copolymers exhibit the following dynamic rheological features: (1) lower viscoelastic moduli and viscosity at small frequencies, but larger viscoelastic moduli and viscosity at large frequencies, thus a small shear thinning effect; (2) larger values of flow activation energy; (3) a relatively fast relaxation rate. These features are the results of simultaneous absence of high molecular weight tails and low molecular weight tails in the metallocene-based copolymers. The dynamic rheological properties of blends of various ethylene-butene copolymers with LDPE were also investigated. It is found that the addition of LDPE can raise the viscosity at low frequencies but lower the viscosity and elasticity at higher frequencies, and retard the relaxation rate of the metallocene-based ethylene copolymers. However, the improvement in rheological properties by LDPE varies with the polymer samples and there is no improvement for the conventional copolymer G.     

Micro-composite systems by in-situ formation of liquid crystal polymers in commodity polymers

In-situ formation of polyimide was carried out in solution of copolymers derived from styrene and 4-vinylpyridine. The in-situ formed polyamic acid formed a strong hydrogen-bonding with pyridine moiety of the copolymers, resulting in homogeneous solutions. Cast films obtained from the solutions were clear and transparent without phase separations, and mechanical properties of the films were much stronger than those of films from the original copolymers. In-situ polymerization of acrylamide in poly(styrene) was carried out by anionic polymerization to form Nylon 3 which was dispersed in poly(styrene) as fine particles, and mechanical properties of the poly (styrene) were greatly improved.     

螺二芴基可溶性共聚物的合成及发光性能

以9,9'-螺二芴和不同链长的二烷氧基苯为单体, 以FeCl3为催化剂, 采用化学氧化法合成了一系列聚合物发光材料. 溶解度测试表明, 共聚物在二氯甲烷、四氢呋喃(THF)、氯仿等极性溶剂中具有良好的溶解性. 利用核磁共振氢谱(1H NMR)、傅里叶变换红外(FT-IR)光谱、紫外-可见(UV-Vis)光谱和荧光(PL)光谱研究了共聚物的化学结构和发光性能, 结果表明共聚物在二甲基亚砜(DMSO)中均发射蓝色荧光, 最大吸收和荧光发射峰分别为356和413 nm. 以硫酸奎宁溶液作为参比, 测得共聚物的荧光量子效率为0.69至0.77. 通过循环伏安法(CV)测得所合成的三种共聚物的最高占有分子轨道(HOMO)能级均位于-5.85至-5.69 eV之间.     

Synthesis and physicochemical properties of polyurethane block copolymers and their compositions with plasticizers

The synthesis of polyurethane block based on oligoesterdiols 4,4′-methylene-bis(phenylisocyanate), and various chain elongating agents was studied. The properties of these copolymers were compared (using literature data) with selected properties of polyurethanes obtained by the reactions of oligoetherdiols, viz., oligo-3,3′-bis(azidomethyl)oxetanediol and oligo-3-azidomethyl-3′-methyloxetanediol with diisocyanates. The complex of rheological and physicomechanical properties of the initial and plasticized polyurethane block copolymers was studied. Regularities of their deformation behavior were established. The process of mutual solubility was studied by the microinterference method for a wide range of systems block copolymers—plasticizers. On the basis of the data obtained, the phase diagrams were constructed for limitedly compatible systems.     

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.     

全共轭聚噻吩类和聚硒吩类嵌段共聚物的凝聚态结构调控

嵌段共聚物可发生微相分离形成丰富的介观尺度上的相结构,而共轭聚合物是一类具有特殊的力学、导电性能或光电功能的半刚性链高分子.全共轭嵌段共聚物因其兼具两者的特性而备受瞩目.本文着重介绍了近年来课题组在基于全共轭聚(3-烷基噻吩)和聚(3-烷基硒吩)嵌段共聚物体系的研究进展,通过改变体系的分子结构包括主侧链结构、侧链的烷基长度及取代基团等以及对体系在溶液状态及薄膜状态进行后处理包括改变溶剂、热处理、溶剂蒸气处理等来调控体系的微相分离行为和结晶行为,实现对材料凝聚态结构的调控.在此基础上,以有机场效应晶体管和聚合物太阳能电池器件作为最终体现聚噻吩或聚硒吩类体系凝聚态结构与性能关系的平台,将获得的调控体系凝聚态结构的有效策略用于实现其半导体材料物理性能的提升.     

Electrochemical copolymerization of 9,10-dihydrophenanthrene and 3-methylthiophene and characterization of their copolymer with tunable fluorescence properties

Electrochemical copolymerization of 9,10-dihydrophenanthrene and 3-methylthiophene was successfully achieved in boron trifluoride diethyl etherate by direct anodic oxidation of the monomer mixtures. The structure and properties of the copolymers were investigated with ultraviolet–visible, Fourier transform infrared spectroscopy, ¹H nuclear magnetic resonance, fluorescence spectra, and thermal analysis. The novel copolymers had the advantages of both poly(9,10-dihydrophenanthrene) and poly(3-methylthiophene), such as good electrochemical behavior, good mechanical properties, and high electrical conductivity. Fluorescence spectroscopy studies revealed that the copolymers had good fluorescence properties, and the emitting properties of the copolymer could be parameters by changing the feed ratio of the monomer mixtures during the electrochemical polymerization.     

Synthesis and drug release properties of novel pH- and temperature-sensitive copolymers based on a hyperbranched polyether core

Multi-arm star amphiphilic hyperbranched copolymers with poly(2-(dimethylamino) ethyl methacrylate) (PDMAEMA) shell and hyperbranched poly(3-ethyl-3-(hydroxymethyl)oxetane) (HBPO) core were synthesized by reversible addition?Cfragmentation chain transfer method. The hyperbranched copolymers were further modified by succinic anhydride (SUC) to obtain the novel pH- and thermosensitive hyperbranched copolymer HBPO-star-PDMAEMAs-SUC. The composition and morphology of synthesized copolymers were investigated by ¹H NMR, dynamic light scattering, and transmission electron microscopy. These copolymers exhibited phase transitions in response to pH and temperature. The pH-dependent release properties of the drug-loaded micelles were also investigated using indomethacin (IND) as a model drug. The IND-loaded micelles displayed a rapid drug release at an alkaline pH.     

Preparation and characterization of biodegradable nanoparticles based on amphiphilic poly(3-hydroxybutyrate)-poly(ethylene glycol)-poly(3-hydroxybutyrate) triblock copolymer

Amphiphilic triblock copolymers of poly(3-hydroxybutyrate)-poly(ethylene glycol)-poly(3-hydroxybutyrate) (PHB-PEG-PHB) were directly synthesized by the ring-opening copolymerization of β-butyrolactone monomer using PEG as macroinitiator. Their structure, thermal properties and crystallization were investigated by ¹H NMR, differential scanning calorimetry (DSC) and X-ray diffraction. It was found that both PHB and PEG blocks were miscible. With the increase in the PHB block length, the triblock copolymers became amorphous because amorphous PHB block remarkably depressed the crystallization of the PEG block. Biodegradable nanoparticles with core-shell structure were prepared in aqueous solution from the amphiphilic triblock copolymers, and characterized by ¹H NMR, SEM and fluorescence. The hydrophobic PHB segments formed the central solid-like core, and stabilized by the hydrophilic PEG block. The nanoparticle size was close related to the initial concentrations of the nanoparticle dispersions and the compositions of the triblock copolymers. Moreover, the PHB-PEG-PHB nanoparticles also showed good drug loading properties, which suggested that they were very suitable as delivery vehicles for hydrophobic drugs.     

Synthesis and characterization of all‐conjugated copolymers of 3‐hexyl‐thiophene and EDOT by grignard metathesis polymerization

Random regioregular copolymers of 3‐hexylthiophene and 3,4‐ethylenedioxythiophene were synthesized by grignard metathesis polymerization. Soluble copolymers were obtained with a high degree of regioregularity and with a monomer ratio close to the feed ratio. A comparison between the optical properties and the thin film morphologies of these copolymers and poly(3‐hexylthiophene) is also presented. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011