Effect of segmented poly(ester-siloxane)urethanes compositional parameters on differential scanning calorimetry and dynamic-mechanical measurements

Segmented poly(ester-siloxane)urethanes containing hard and soft segments were prepared by melt polyaddition using a multistep procedure. The soft segments based on poly(ethylene glycol adipate)diol as ester sequences and α,ω-poly(dimethylsiloxane)diol as silicone sequences were synthesized. The hard segments were based on aromatic or aliphatic diisocyanates and butanediol was used as chain extender. These polyurethane materials were analysed by differential scanning calorimetry and dynamic-mechanical analysis measurements. The shapes of thermal plots are significantly influenced by the soft and hard segment structures and also the compositional parameters.     

磺化苯乙烯-马来酸酐共聚物

磺化苯乙烯-马来酸酐共聚物是由苯乙烯-马来酸酐共聚物直接磺化并中和成钠盐制备。由于它分子中含有很多磺酸及羧酸负离子,因此,是一很好的阴离子聚电解质,被广泛用于泥浆稀释剂、水泥添加剂和皮革鞣剂等。     

Synthesis and characterization of biodegradable polymer： Poly （ethene maleic acid ester-co-D,L-lactide acid）

A novel biodegradable polymer--poly （ethene maleic acid ester-co-D,L-lactide acid） was synthesized by copolymerizing lactide and prepolymer, which was prepared by the condensation of maleic anhydride and glycol, using p-toluene sulphonic acid as a catalyst, attempting to improve the hydrophilicity, increase flexibility and modulate the degradation rate. FTIR,^1H NMR, MALLS and DSC were employed to characterize these polymers.     

两亲嵌段共聚物溶液内胶束形成的温度效应

合成了一系列具有两亲嵌段结构的聚（乙二醇）（PEO）一聚（丙二醇）（PPO）共聚物．利用荧光探针及示差量热法测定了共聚物水溶液的临界胶束形成温度（CMT）值．发现二嵌段共聚物（PEO－PPO）和三嵌段共聚物（PEO－PPO－PEO）有着类似的变化规律，即随共聚物分子中疏水链（PPO）长度的增大，其CMT值降低．但三嵌段共聚（PPO－PEO－PPO）则因疏水链段处于共聚物分子的两端，因而在溶液中有可能形成立体网状交联结构．此外，利用探针分子在不同极性溶剂中荧光峰值波长发生位移的现象可以对形成胶束内核的组织程度、极性大小进行估测．     

Glass transitions and mixed phases in block SBS

Differential scanning calorimetry (DSC) does not allow for easy determination of the glass‐transition temperature (T_g) of the polystyrene (PS) block in styrene–butadiene–styrene (SBS) block copolymers. Modulated DSC (MDSC), which deconvolutes the standard DSC signal into reversing and nonreversing signals, was used to determine the (T_g) of both the polybutadiene (PB) and PS blocks in SBS. The T_g of the PB block was sharp, at ?92 °C, but that for the PS blocks was extremely broad, from ?60 to 125 °C with a maximum at 68 °C because of blending with PB. PS blocks were found only to exist in a mixed PS–PB phase. This concurred with the results from dynamic mechanical analysis. Annealing did not allow for a segregation of the PS blocks into a pure phase, but allowed for the segregation of the mixed phase into two mixed phases, one that was PB‐rich and the other that was PS‐rich. It is concluded that three phases coexist in SBS: PB, PB‐rich, and PS‐rich phases. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 276–279, 2005     

苯乙烯-N-苯基马来酰亚胺-马来酸酐三元共聚物的合成与性能

以过氧化对苯二甲酸二叔丁酯为引发剂, 以一次投料方式, 采用溶液聚合法合成了苯乙烯-N-苯基马来酰亚胺-马来酸酐三元共聚物. 通过控制单体配比, 实现产物中N-苯基马来酰亚胺质量分数在48%~63%之间可调. 采用FTIR, ¹H NMR, ¹³C NMR和GPC技术对三元共聚物的化学组成、链序列结构和分子量进行了测试. 利用FOX方程计算的共聚物NPMI含量与¹H NMR核磁测试结果一致. DSC和TGA测试的结果表明, 当N-苯基马来酰亚胺质量分数>48%时, 共聚物的玻璃化转变温度(T_g)从202 ℃提高到215 ℃, 5%热失重温度高于363 ℃, 所以三元聚合物是一种优异的聚合物耐热剂.     

Miscibility as a function of copolymer composition in blends of a random copolymer and a homopolymer

Random copolymers of n-butyl acrylate (BA) and cyclohexyl acrylate (CHA) were synthesized by solution polymerization in cyclohexane. Blends of polystyrene with the poly(CHA-stat-BA) copolymers were prepared by solvent casting and coprecipitation. The miscibility of the blends was characterized by means of differential scanning calorimetry. While blends with a low content of CHA in the copolymer showed two characteristic glass-transition temperatures of the corresponding blend components, those with a CHA content higher than 70% presented good compatibility. Phase separation of the miscible blends took place after annealing at 200 °C for 1 h, which implies an upper miscibility gap (lower critical solution temperature).     

抗冲级SMA树脂的合成及研究进展

从脆性树脂的增韧机理出发，讨论了影响增韧SMA抗冲性能的主要工艺因素，比较了制备抗冲级SMA的近期研究的本体法、溶液法和拟本体法工艺特点，预期综合性能优良的抗冲级SMA材料有良好的应用前景。     

Simple analytical method for determination of microstructures of poly(ethylene-co-vinyl acetate) using the melting points

Microstructures of poly (ethylene-co-vinyl acetate) (EVA) are dependent on the distribution of VA units as well as the VA content. Simple analytical method to determine microstructure of EVA was established using melting points of EVA and correlationship with those of wax and its ester. EVAs with the VA contents of 9.5–40 wt% (3.3–17.8 mol%) were used. The melting points were analyzed using differential scanning calorimetry (DSC). EVAs had two melting points of T_m1 and T_m2 at 96–44 and 56 - 36 °C, respectively. The melting points were found to be closely related to the minimum carbon number participating in the crystal formation (CN_min). The crystalline size could be estimated by equation of CN_min = - ln [(106.7 - T_m)/214.8]/0.055 + 15. The CN_min1 and CN_min2 were 68–38 and 41–35, respectively. The CN_min1 decreased by about 4.5/mol% until 6.7 mol% of the VA content, while the CN_min2 slightly decreased by about 0.4/mol%. It was found that EVA would be generally composed of three ethylene block sizes of ~VA-(CH₂CH₂)_c1>20-VA-(CH₂CH₂)_15<c2<20-VA-(CH₂CH₂)_a<15-VÃ (c1 and c2: crystalline regions, a: amorphous region). Size of the amorphous region became smaller by increasing the CN_mins. EVAs deviated from the average trends could be explained by difference in the microstructures such as the ethylene block sizes and branched structures. It was possible to explain difference in the microstructures of EVAs with the same VA content by difference in the CN_mins obtained using the T_ms.     

Radiation grafting of styrene and maleic anhydride onto PTFE membranes and sequent sulfonation for applications of vanadium redox battery

Using γ-radiation technique, poly(tetrafluoroethylene) (PTFE) membrane was grafted with styrene (St) (PTFE-graft-PS) or binary monomers of St and maleic anhydride (MAn) (PTFE-graft-PS-co-PMAn), respectively. Then grafted membranes were further sulfonated with chlorosulfonic acid into ion-exchange membranes (denoted as PTFE-graft-PSSA and PTFE-graft-PSSA-co-PMAc, respectively) for application of vanadium redox battery (VRB). Micro-FTIR analysis indicated that PTFE was successfully grafted and sulfonated at the above two different conditions. However, a higher degree of grafting (DOG) was obtained in St/MAn binary system at the same dose due to a synergistic effect. Comparing with PTFE-graft-PSSA, PTFE-graft-PSSA-co-PMAc membrane showed higher water uptake and ion-exchange capacity (IEC) and lower area resistance (AR) at the same DOG. In addition, PTFE-graft-PSSA-co-PMAc with 6% DOG also showed a higher IEC and higher conductivity compared to Nafion membrane. Radiation grafting of PTFE in St/MAn binary system and sequent sulfonation is an appropriate method for preparing ion-exchange membrane of VRB.     

阴离子磺酸盐型Gemini表面活性剂与PEO-PPO-PEO嵌段共聚物相互作用的研究

用差示扫描微量热、等温滴定微量量热、动态光散射和核磁共振(NOESY,弛豫时间)技术,研究了在pH＝9时阴离子磺酸盐型Gemini表面活性剂12-3-12(SO₃)₂与PEO-PPO-PEO嵌段共聚物F127 (EO₉₇PO₆₉EO₉₇)和P123 (EO₂₀PO₇₀EO₂₀)之间的相互作用. 研究发现,随着12-3-12(SO₃)₂浓度的增大,聚合物的临界胶束温度(CMT)降低. 与传统的单链离子表面活性剂相比,12-3-12(SO₃)₂具有更强的降低共聚物CMT的能力. 此外,在低于聚合物的CMT时,12-3-12(SO₃)₂与聚合物单体可以形成聚合物/表面活性剂胶束聚集体;在高于聚合物的CMT时,12-3-12(SO₃)₂的加入首先与聚合物单体和胶束的混合物或聚合物胶束形成聚合物/12-3-12(SO₃)₂混合胶束,然后随着12-3-12(SO₃)₂浓度的增大,混合胶束逐步解离为小的聚集体,但是,即使在很高的12-3-12(SO₃)₂浓度时,混合胶束也未完全解离.     

双酚-S环氧树脂与琥珀酸酐固化反应动力学

用差示扫描量热法（ＤＳＣ）研究了双酚－Ｓ环氧树脂（ＢＰＳＥＲ）与琥珀酸酐固化反应的历程。实验结果表明,固化反应主要分两个阶段,前期由化学动力学控制,服从自催化机理。实验数据利用Ｋａｍａｌ方程处理得到两个速率常数ｋ、、ｋ２及两个反应级数ｍ、ｎ、ｋ１、ｋ２的值随反应温度的升高呈增大的趋势,总反应级数ｍ＋ｎ在２～２．５之间,当转化率达到４０％左右后,由于交联程度增加,分子量迅速增长,分子间扩散较慢,进入     

Synthesis and self-assembly of comb-like amphiphilic copolymer poly(maleic anhydride-<Emphasis Type="Italic">alt</Emphasis>-stearyl methacrylate)-<Emphasis Type="Italic">b</Emphasis>-poly(stearyl methacrylate)

Comb-like amphiphilic block copolymers of maleic anhydride (MA) and stearyl methacrylate (SMA) were prepared through the reversible-addition-fragmentation-transfer polymerization. The resultant copolymers were characterized by gel permeation chromatograph and ¹H NMR. The aggregation behaviors of P(MA-alt-SMA)-b-PSMA were investigated in tetrahydrofuran/water. It is of great interest that the aggregates with different morphologies and dimensions could be obtained by adjusting the polymer concentration, water content, and pH. The dimension and structure of these aggregates were investigated by transmission electron microscopy and dynamic light scattering. The effect of the copolymer–solvent interaction on these aggregations was discussed.     

Three models for chain conformation of block copolymers in solution and in solid state

Solution properties of polystyrene-poly(methyl methacrylate) (PS-PMMA) diblock copolymer, polystyrene-poly(tertiobutyl methacrylate) (PS-PtBuMA) diblock copolymer, and poly(ethylene oxide)-polystyrene-poly(ethylene oxide) (PEO-PS-PEO) triblock copolymer have been measured by viscometry. The PEO-PS-PEO copolymer has been studied also in solid state by differential scanning calorimetry and by optical microscopy. All the block copolymers present a conformational transition in solution at a given temperature region which is relatively narrow. If below this transition temperature a copolymer adopts a segregated conformation (dumb-bell model), above this transition adopts a nonsegregated or pseudo-gaussian conformation, and vice versa. In the transition temperature region the copolymer adopts a compressed segregated conformation (core and shell model). If the passage from the solution to the solid state is performed in a given constant temperature in which the copolymer presents a segregated or nonsegregated conformation the same conformation is observed in the solid state (memory effect). © 1996 John Wiley & Sons, Inc.     

Synthesis and Characterization of Amphiphilic Block Copolymer by Block Copolymerization of Butadiene and Acrylamide using Macroazoinitiator

Abstract

Macroazoinitiator (MAI) was prepared from hydroxyl‐terminated polybutadiene (HTPB) and 4,4′‐azobis‐4‐cyanopentanoic acid by direct polycondensation in the presence of 1‐methyl‐2‐chloropyridinium iodide at room temperature. This MAI used for block copolymerization of AAm at 60°C gave the best results in chloroform but the formation of a crosslinked product could not be ruled out in dioxane. It was inferred that for production of a linear block copolymer, homogeneous reaction mixture was required.

The resulting products were characterized by spectral studies IR and NMR, viscosity measurements. Distinct phase segregation of hydrophobic and hydrophilic blocks was evident through DSC analysis.     

Synthesis, optical, and thermal properties of conjugated, bispyridyl and tetrapyridyl compounds by Knoevenagel reaction

A series of conjugated, bispyridyl and tetrapyridyl compounds were synthesized from either terephthalaldehyde or isophthalaldehyde and activated pyridyl compounds by Knoevenagel reaction on heating in acetic anhydride in presence of acetic acid and their optical and thermal properties were examined. All of them exhibited photoluminescence in chloroform, tetrahydrofuran, and dimethyl sulfoxide as well as in solid state. In solid state, their emission spectra exhibited bathochromic shifts when compared with those in less or more polar solvents. Some compounds emitted UV light both in polar solvents and in the solid state; other compounds emitted UV light in polar solvents, but emitted visible light in the solid state.     

Synthesis of Diblock Copolymers With Cellulose Derivatives. 2. Characterization and Thermal Properties of Cellulose Triacetate-Block-Oligoamide-15

Well-defined A-block-B type cellulose derivatives consisting of cellulose triacetate (CTA) and oligoamide-15 were synthesized. Chemical structures of the diblock copolymers were characterized by MALDI-TOF MS, ¹H-NMR, and GPC. Influence of length of CTA and oligoamide-15 segments on their thermal properties was investigated by means of differential scanning calorimetry (DSC). All diblock copolymers displayed T _g, T _c, and T _m transition temperatures. Their T _g and T _m values increased with the increase of molecular weight of CTA segment. The crystallinity of diblock copolymers increased after isothermal crystallization at 200 °C. Its X-ray analysis revealed that the diblock copolymer had CTA II crystal structure. Thermal analysis supported microphase separation between CTA and oligoamide-15 segments at room temperature, because T _g and T _m values of polyamide-15 are −7 °C and 170–180 °C, respectively.     

Reactive functionalization of poly(lactic acid), PLA: Effects of the reactive modifier,initiator and processing conditions on the final grafted maleic anhydride content and molecular weight of PLA

A response surface methodology (RSM) design was used to analyze the effects of maleic anhydride (MA) and 2,5-bis(tert-butylperoxy)-2,5-dimethyl hexane (Luperox or L101) content, and TSE screw speed on the degree of grafted MA (MA_g) and number average molecular weight (M_n) of maleated PLA (PLA-g-MA), which can be used as a reactive compatibilizer in production of PLA blends with various components. PLA-g-MA's FTIR peaks indicated that MA was grafted onto the PLA backbone and oligomeric MA was also present. A maximum of 0.52 wt% MA_g determined by titration was achieved at the expense of a 50% reduction of M_n and an increase in the polydispersity index to around 2.0. Generally, increasing L101 increased the degree of grafting and decreased M_n. L101 and MA_g had a large effect on the stability of PLA-g-MA's M_n during storage. Nominally, amounts of MA equal to 4.5 wt%, L101 between 0.45 and 0.65 wt%, and screw speed of 20 rpm provided the optimal conditions for grafting MA onto PLA.     

Crystallization of tethered polyethylene in confined geometries

Ordered poly(ethylene)‐poly(vinylcyclohexane) (PE‐PVCH) block copolymers are employed to study the crystallization of tethered PE in confined geometries. The high T_g of the PVCH component of these materials forces PE chains to crystallize in well‐defined geometries dictated by the mesophase structure of the block copolymer. Effects of chain tethering on crystallization are examined through comparison of singly‐tethered PE chains in PE‐PVCH (EV) diblocks and doubly‐tethered PE in PVCH‐PE‐PVCH (VEV) triblocks. Crystallinity is independent of the block copolymer mesophase structure in both the EV and VEV systems, although crystallinity in VEV depends on the molecular weight of the PE block of the copolymer. Melting temperature data indicate that spatial confinement reduces crystallite size in EV and VEV, and that the double tethering of PE chains in VEV reduces crystallite size further through topological constraints. Crystal nucleation and growth depend strongly on the type of microstructure in both EV and VEV block copolymers. Differences in the overall rate of crystallization are correlated with the dimensional continuity of the PE microdomains. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37:2053–2068, 1999     

示差扫描量热法进展及其在高分子表征中的应用

示差扫描量热法(DSC)是表征材料热性能和热反应的一种高效研究工具,具有操作简便、应用广泛、测量值物理意义明确等优点.近年来DSC技术的发展大大拓展了高分子材料表征的测试范围,促进了对高分子物理转变的热力学和动力学的深入研究.温度调制示差扫描量热法(TMDSC)是DSC在20世纪90年代的标志性进展,它在传统DSC的线性升温速率的基础之上引入了调制速率,从而可将总热流信号分解为可逆信号和不可逆信号两部分,并能测量准等温过程的可逆热容.闪速示差扫描量热法(FSC)是DSC技术近年来的创新性发展,它采用体积微小的氮化硅薄膜芯片传感器替代传统DSC的坩埚作为试样容器和控温系统,实现了超快速的升降温扫描速率以及微米尺度上的样品测试,使得对于高分子在扫描过程中的结构重组机制的分析以及对实际的生产加工条件的直接模拟成为可能.本文从热分析基础出发,依次对传统DSC、TMDSC和FSC进行了介绍,内容覆盖其发展历史、方法原理、操作技巧及其在高分子表征中的应用举例,最后对DSC未来的发展和应用进行了展望.本文希望通过综述DSC原理、实验技巧和应用进展,帮助读者加深对DSC这一常用表征技术的理解,进一步拓展DSC表征高分子材料的应用.