苯乙烯-丁二烯-苯乙烯/聚乙烯基甲基醚共混体系相容性的FT-IR及DSC研究

嵌段高聚物、均聚物共混体系相容性是近年来研究的热点。本工作以光学显微镜、DSC、FT-IR为手段,研究了三嵌段高聚物苯乙烯-丁二烯-苯乙烯(SBS);SBS-48、SBS-30,SBS-28与聚乙烯基甲基醚共混体系的相容性。DSC结果表明,随SBS中PS含量的升高,体系相容性变好,PS段分子量增大,也有助于体系相容。FT-IR结果表明PVME中COCH_3在1100cm~(-1)附近呈现的双峰的相对强度对体系的相容性十分敏感,而由于苯环C—H振动产生的698cm~(-1)峰位却不象PS/PVME体系那样随相容性的改变而有显著的改变。总而言之,嵌段高聚物SBS/均聚物PVME共混体系中,体系的相容性依赖于嵌段高聚物在体系中的组份含量及嵌段高聚物中PS的重量百分含量,PS段分子量的大小对体系相容性也有影响。     

FT–IR spectroscopic and thermal studies of poly(styrene-co-1-vinyl naphthalene) and poly(vinyl methyl ether) blends

The FT–IR spectroscopic analysis and the thermal behavior of the blends of styrene-1-vinyl naphthalene copolymers [P(S-co-1VN)] and poly(vinyl methyl ether) (PVME) were investigated in this work. The copolymers containing 23, 50, and 80% by weight of styrene were synthesized by radical polymerization. The blend films of the P(S-co-1VN) and PVME were cast from the mixed solvent of benzene/trimethylbenzene [50/50 (v/v)]. It was found from the optical clarity and the glass transition temperature behavior that the blends of PVME with P(S-co-1VN) of 80 wt % styrene and 20 wt % 1-vinylnaphthalene (1VN) show miscibility below 50 wt % of the copolymer concentration and the concentration range to show miscibility becomes wider as the composition of 1VN decreases in the copolymers. From the FT–IR results, the relative peak intensity of the 1100 cm^?1 region due to COCH₃ bond of PVME and the peak position of 774 cm^?1 region due to the naphthyl ring of 1VN were sensitive to the miscibility of the P(S-co-1VN)/PVME blends. The frequency differences of the phenyl ring and the naphthyl ring in the P(S-co-1VN) from each frequency in the P(S-co-1VN)/PVME blends increase with increasing composition of styrene in the copolymers and with increasing concentration of PVME in the blends. A threshold energy exists to induce molecular interaction between the naphthyl ring of 1VN and the COCH₃ of PVME and to result in the miscible blends, regardless of the copolymer composition as well as the blend concentration. The threshold energy was estimated as about 3.689 × 10^?21 cal (779 cm^?1) for the P(S-co-1VN)/PVME blend system. It can be concluded that the miscibility in P(S-co-1VN)/PVME blends is largely affected by the composition of the copolymers, and the blends become more miscible as the composition of styrene in the copolymers increases.     

Miscibility of poly(vinyl methyl ether) and poly(styrene-co-2-vinylnaphthalene) blends by FT-IR spectroscopy and Tg measurements

Miscibility of blends consisting of poly(vinyl methyl ether) (PVME) and poly(styreneco-2-vinylnaphthalene) [P(S-co-2VN)] was investigated by means of Fourier transform infrared (FT-IR) spectroscopy and thermal analysis. Copolymers containing 21, 51, and 84 wt % of styrene were synthesized by radical polymerization. Based on optical clarity and glass transition temperatures, it was shown that the miscibility in P(S-co-2VN)/PVME blends is largely affected by compositions of the copolymers as well as concentrations of the blend. From the FT-IR results, the relative intensity at 1100 cm^?1 peak of COCH₃ band of PVME and the position of naphthyl ring of 2VN were sensitive to the miscibility of the blends. It was observed that blends of PVME with P(S-co-2VN) of 84 wt % styrene or P(S-co-2VN) of 51 wt % styrene are miscible over the entire concentration ranges of the blends. Blends of PVME with P(S-co-2VN) containing 21 wt % of styrene are immiscible below 65 wt % PVME. In the miscible P(S-co-2VN)/PVME blends, there was observed a large shift in the naphthyl frequency at a characteristic wavelength of 748 cm^?1. © 1993 John Wiley & Sons, Inc.     

Miscibility and Thermal Behaviour of Poly(styrene-co-itaconic acid)/Poly(butyl methacrylate-co-4-vinylpyridine) Mixtures. Accessibility and Self-Association Effects

Summary: The miscibility and thermal behaviour of binary mixtures of poly(styrene-co-itaconic acid) containing 11 or 27 mol % of itaconic acid (PSIA-11 or PSIA27) with poly(butyl methacrylate) (PBMA)or poly(butyl methacrylate-co-4-vinylpyridine) containing 10 or 26 mol% of 4-vinylpyridine (PBM4VP-10, PBM4V-P26) were investigated by differential scanning calorimetry, scanning electron microscopy, FTIR spectroscopy and thermogravimetry. The results showed that 11 mol % of itaconic acid and 10 mol % of 4-vinylpyridine respectively introduced within the polystyrene and poly(butyl methacrylate) matrices induced the miscibility of this pair of polymers due to specific interactions of hydrogen bonding type with partial pyridine protonation that occurred between the two copolymers as evidenced by FTIR from the appearance of two new bands at 1607 cm⁻¹ and 1640 cm⁻¹. Increasing itaconic acid content from 11 to 27 mol % led to a decrease of the intensity of the specific interactions within PSIA-27/PBM4VP blends and is attributed to both accessibility and self association effects as evidenced by DSC from the change of the shape of the Tg- composition curves and by FTIR spectroscopy. As shown from the thermogravimetric study, the presence of these specific interactions delayed the anhydride formation and improved the thermal stability of the blends.     

Phase behavior in mixtures of a homopolymer and a block copolymer. 4. SALS and SAXS studies

Phase behavior of blends of poly(vinyl methyl ether) (PVME) with four styrene-butadiene-styrene (SBS) triblock copolymers, being of various molecular weights, architecture, and compositions, was investigated by small-angle light scattering. Small-angle X-ray scattering investigation was accomplished for one blend. Low critical solution temperature (LCST) and a unique phase behavior, resembling upper critical solution temperature (UCST), were observed. It was found that the architecture of the copolymer greatly influenced the phase behavior of the blends. Random phase approximation theory was used to calculate the spinodal phase transition curves of the ABA/C and BAB/C systems; LCST and resembling UCST phase behavior were observed as the parameters of the system changed. Qualitatively, the experimental and the theoretical results are consistent with each other. © 1996 John Wiley & Sons, Inc.     

Fourier-transform infrared study of polystyrene/poly(vinyl methyl ether) blends

Fourier-transform infrared (FTIR) studies of polystyrene (PS)/poly(vinyl methyl ether) (PVME) blends are presented. Both compatible (one-phase) and phase-separated blends were studied. In the case of compatible PS/PVME blends, there is strong evidence for molecular interactions. The interaction spectrum was obtained by digital subtraction techniques. In contrast, no interaction is detected for the phase-separated blends. In view of these results, molecular interactions must play a role in the compatibility of the two polymers. The merits of factor analysis and least-squares fit methods, as pertaining to our data, are also discussed.     

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).     

High-temperature fourier transform infrared study of polystyrene/poly(vinyl methyl ether) blends

Fourier transform infrared (FTIR) studies of polystyrene (PS)/poly(vinyl methyl ether) (PVME) miscible blends as a function of temperature are presented. Below the lower critical solution temperature (LCST) little change is observed in the interaction spectrum obtained via digital subtraction techniques. Once above the LCST, the magnitude of the interaction spectrum decreases as a result of the phase separation process. Comparison of the behavior of the ether C? O stretching band in the reference PVME and in the blends has yielded a lower limit estimate for the interaction energy of about 0.15 kcal/mol.     

Preparation and properties of phenylene oxide–aryl ether sulphone block copolymers and their blends

We have prepared triblock copolymers of poly(phenylene oxide) (PPO) and polysulphone (PSF) of the form PPO–PSF–PPO in order to assess their intrinsic mechanical properties and their potential as interfacial compatibilizers in polystyrene/PSF blends. For sufficiently long polysulphone block lengths, we observed microphase separation both in the triblock copolymers and in their blends with polystyrene. The triblock polymers, nevertheless, showed very similar microdeformation behavior to the PPO homopolymer, suggesting the phase separation to play a minor role. On the other hand, the compatibility of the poly(phenylene oxide) blocks and polystyrene ensured a high degree of interphase adhesion in blends containing both polystyrene and free PSF, even for relatively high homopolymer molecular weights. © 1996 John Wiley & Sons, Inc.     

聚苯乙烯溶胀聚苯乙烯－聚丁二烯－聚苯乙烯三嵌段共聚物微区的研究

嵌段共聚物/均聚物共混体系,各嵌段会形成各自的相,并且嵌段间的连接点一定在两相之间的界面上,这一要求极大地影响了嵌段共聚物/均聚物共混体系的链构象和相行为.     

Unexpected consequences of block polydispersity on the self-assembly of ABA triblock copolymers

Controlled/"living" polymerizations and tandem polymerization methodologies offer enticing opportunities to enchain a wide variety of monomers into new, functional block copolymer materials with unusual physical properties. However, the use of these synthetic methods often introduces nontrivial molecular weight polydispersities, a type of chain length heterogeneity, into one or more of the copolymer blocks. While the self-assembly behavior of monodisperse AB diblock and ABA triblock copolymers is both experimentally and theoretically well understood, the effects of broadening the copolymer molecular weight distribution on block copolymer phase behavior are less well-explored. We report the melt-phase self-assembly behavior of SBS triblock copolymers (S = poly(styrene) and B = poly(1,4-butadiene)) comprised of a broad polydispersity B block (M(w)/M(n) = 1.73-2.00) flanked by relatively narrow dispersity S blocks (M(w)/M(n) = 1.09-1.36), in order to identify the effects of chain length heterogeneity on block copolymer self-assembly. Based on synchrotron small-angle X-ray scattering and transmission electron microscopy analyses of seventeen SBS triblock copolymers with poly(1,4-butadiene) volume fractions 0.27 ≤ f(B) ≤ 0.82, we demonstrate that polydisperse SBS triblock copolymers self-assemble into periodic structures with unexpectedly enhanced stabilities that greatly exceed those of equivalent monodisperse copolymers. The unprecedented stabilities of these polydisperse microphase separated melts are discussed in the context of a complete morphology diagram for this system, which demonstrates that narrow dispersity copolymers are not required for periodic nanoscale assembly.     

Blends of poly(2,6–dimethyl–1,4–phenylene oxide) with styrene copolymers

Binary blends of poly(2,6–dimethyl–1,4–phenylene oxide) (PPE) with various styrene copolymers were investigated. Poly(styrene–co–acrylonitrile) (SAN), poly[styrene–co–(methyl methacrylate)] (SMMA), poly[styrene–co–(acrylic acid)] (SAA) and poly[styrene–co–(maleic anhydride)] (SMA) are only miscible with PPE when the amount of comonomer is rather small. From calculated binary interaction densities it can be concluded that the strong repulsion between PPE and comonomer limits miscibility. In blends of PPE with SAN, as well as with ABS, the inter-facial tension between the blend components is significantly reduced upon addition of polystyrene–block–poly–(methyl methacrylate) diblock copolymers (PS–b–PMMA) and polystyrene–block–poly (ethylene–co–butylene)–block–poly–(methyl methacrylate) triblock copolymers (PS–b–PEB–b–PMMA). They show a profound influence on morphology, phase adhesion and mechanical blend properties.     

Reactively and physically compatibilized immiscible polymer blends: stability of the copolymer at the interface

This paper reports on the interfacial behaviour of block and graft copolymers used as compatibilizers in immiscible polymer blends. A limited residence time of the copolymer at the interface has been shown in both reactive blending and blend compatibilization by preformed copolymers. Polystyrene (PS)/polyamide6 (PA6), polyphenylene oxide (PPO)/PA6 and polymethylmethacrylate (PMMA)/PA6 blends have been reactively compatibilized by a styrene-maleic anhydride copolymer SMA. The extent of miscibility of SMA with PS, PPO and PMMA is a key criterion for the stability of the graft copolymer at the interface. For the first 10 to 15 minutes of mixing, the in situ formed copolymer is able to decrease the particle size of the dispersed phase and to prevent it from coalescencing. However, upon increasing mixing time, the copolymer leaves the interface which results in phase coalescence. In PS/LDPE blends compatibilized by preformed PS/hydrogenated polybutadiene (hPB) block copolymers, a tapered diblock stabilizes efficiently a co-continuous two-phase morphology, in contrast to a triblock copolymer that was unable to prevent phase coarsening during annealing at 180°C for 150 minutes.     

聚合物共混物的超高效液相色谱-空间排阻色谱在线联用分离与表征

黏合剂和涂料行业中, 聚合物共混物表征是分析的难题, 分离技术的研究一直备受关注. 本文设计并搭建了超高效液相色谱-空间排阻色谱在线联用系统(UHPLC-SEC), 采用羟基聚丁二烯(HTPB)考察了二维色谱系统的溶剂兼容性及正交性, 以苯乙烯-丁二烯嵌段共聚物(SBS)、 苯乙烯-异戊二烯嵌段共聚物(SIS)和聚甲基丙烯酸酯(PMMA)共混物研究了二维色谱系统的适用性. 结果表明, HTPB分子量及分布的UHPLC-SEC测定结果与SEC测定结果一致, 峰尖分子量(M_p)为3407 Da, 重均分子量(M_w)为6573 Da, 分散系数(PDI)为2.36, 相对标准偏差(RSD)均小于5.7%, 系统的溶剂兼容性和正交性良好. UHPLC-SEC法测得聚合物共混物中PMMA, SBS和SIS的M_p, M_w和PDI与单个聚合物的SEC测定结果的相对误差均小于7.1%. PMMA, SBS和SIS共混物在200 °C加热3 h后, PMMA 稳定不变, SBS和SIS组分明显降解. UHPLC-SEC在线联用方法对聚合物共混物的表征结果准确、 重复性好, 为聚合物配方产品的失效分析提供了一种重要且有效的手段.     

Synthesis and Characterization of Crystalline Styrene‐b‐(Ethylene‐co‐Butylene)‐b‐Styrene Triblock Copolymers

By merit of dual catalysis of the cationic rare‐earth complex [(η⁵‐Flu‐CH₂‐Py)Ho(CH₂SiMe₃)₂(THF) (Flu = fluorenyl, Py = pyridyl) for the living polymerizations of butadiene (BD) and styrene (St), the crystalline styrene‐butadiene‐styrene (SBS) triblock copolymers consisting of elastic polybutadiene (PBD) sequences with suitable 1,4 regularity (about 70%) and crystalline syndiotactic polystyrene (sPS, [rrrr] > 99%) sequences were successfully synthesized through sequential addition of St, BD, and St monomers. The catalytic system showed high polymerization activities for St and BD in a controlled manner. The crystalline styrene‐b‐(ethylene‐co‐butylene)‐b‐styrene (SEBS) triblock copolymers were obtained by hydrogenation of the above SBS copolymers. The observation of a strong endothermic peak at 266 °C in their differential scanning calorimetry (DSC) curves confirmed the existence of the sPS blocks in the crystalline SEBS different from the industrial product Kraton SEBS‐1652. Thermal degradation temperature of the crystalline SEBS (418 ± 2 °C) indicated the well thermostability and process window of this polymer. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 55, 1243–1249     

Ionomeric blends. V. FTIR studies of ionic interactions in polyurethane-styrene blends

FTIR spectra of blends of lightly sulfonated polystyrene (PS-SSA) with polyurethanes (PU) containing a tertiary nitrogen in the chain extender were recorded. These blends exhibit a two-phase behavior, but the individual components are not phase separated. Earlier dynamic mechanical studies suggested the occurrence of proton transfer from the sulfonic acid to the tertiary nitrogen, which enhanced the miscibility via ionic interactions and resulted in the formation of a miscible blend between the PS-SSA and the hard segment of the PU, the soft segment being excluded. FTIR studies of these blends now confirm the proton transfer mechanism. A new absorption band at 3428 cm^?1 corresponds to a stretching vibration of an N⁺?H bond. The 1012 cm^?1 band of the SO₃H group, which strongly depends on the degree of protonation, shifts to lower frequency. The symmetric stretching vibration of the SO group, which occurred at 1043 cm^?1, shifts to lower frequency as well, suggesting a lower polarization of the S? O dipole due to the removal of H⁺.     

Immiscibility,upper critical solution temperature,and miscibility in blends of poly(vinyl ether)s with polyacrylics: Effects of pendant groups

Various phase behavior of blends of poly(vinyl ether)s with homologous acrylic polymers (polymethacrylates or polyacrylates) were examined using differential scanning calorimetry, optical microscopy (OM), and Fourier‐transformed infrared spectroscopy. Effects of varying the pendant groups of either of constituent polymers on the phase behavior of the blends were analyzed. A series of interestingly different phase behavior in the blends has been revealed in that as the pendant group in the acrylic polymer series gets longer, polymethacrylate/poly(vinyl methyl ether) (PVME) blends exhibit immiscibility, upper critical solution temperature (UCST), and miscibility, respectively. This study found that the true phase behavior of poly(propyl methacrylate)/PVME [and poly(isopropyl methacrylate)/PVME)] blend systems, though immiscible at ambient, actually displayed a rare UCST upon heating to higher temperatures. Similarly, as the methyl pendant group in PVE is lengthened to ethyl (i.e., PVME replaced by PVEE), phase behavior of its blends with series of polymethacrylates or polyacrylates changes correspondingly. Analyses and quantitative comparisons on four series of blends of PVE/acrylic polymer were performed to thoroughly understand the effects of pendant groups in either polyethers (PVE's) or acrylic polymers on the phase behavior of the blends of these two constituents. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 1521–1534, 2007     

Blends of styrene/maleic anhydride copolymers with polymethacrylates

The phase behavior of a series of styrene/maleic anhydride (SMA) copolymers with various polyacrylate and polymethacrylate homopolymers has been investigated using various techniques. None of the polyacrylates are miscible with SMA copolymers. Poly (methyl methacrylate) (PMMA) poly(ethyl methacrylate) (PEMA) and poly(n-propyl methacrylate) (PnPMA), are miscible with these copolymers over a certain range of maleic anhydride contents; whereas, the higher methacrylates apparently have no region of miscibility. For PEMA and PnPMA, the miscibility windows extend through 0% MA; hence, polystyrene is miscible with these polymethacrylates although the lower critical solution temperature is quite low. The exothermic heat of mixing styrene and ester analogs found here supports the observed miscibility of polystyrene with ethyl, n-propyl, and cyclohexyl (reported elsewhere) methacrylates. Lattice fluid interaction parameters for styrene-methacrylate obtained from the cloud points of these blends agree quite well with the Flory—Huggins parameters obtained from copolymer miscibility windows.     

Effect of transesterification products on the miscibility and phase behavior of poly(trimethylene terephthalate)/bisphenol A polycarbonate blends

Blends of poly(trimethylene terephthalate)/bisphenol A polycarbonate (PTT/PC) with different compositions were prepared by melt blending. The effect of transesterification on the miscibility and phase behavior of the blends was studied using DSC, DMA, and ¹H NMR. The DMA results revealed a two-phase system with partial miscibility. DSC thermograms of the first heating scan showed a crystallizable system in which addition of PC-phase reduces the degree of crystallinity. However, the cooling and also the second heating scans revealed the complete miscibility of all the blends. It was concluded that annealing at 300 °C (to remove thermal history of the blends) caused the constituents to undergo the transesterification reaction, which changes the blend to a miscible system. The miscibility is due to formation of block copolymers with different block lengths which also suppress the crystallization of the system. The degree of randomness and sequence lengths of the copolymers were determined to analyze the extent of transesterification reaction and structure of the system. It was observed that as the reaction progresses, the degree of randomness increases and the sequence length of the copolymers decreases. Moreover, both increase of reaction time and temperature increased the extent of reaction. The results of DSC and ¹H NMR showed that a small amount of reaction is needed to change this system to a miscible blend.     

Deformation behavior of triblock copolymers based on polystyrene: an FT-IR spectroscopy study

The effect of the long range order and thermal treatment on the micromechanical deformation of two triblock copolymers was investigated, i.e. polystyrene-b-polybutadiene-b-polycaprolactone (SBC) triblock copolymer with PS as the matrix and PCL cylindrical domains and a SBS triblock copolymers with 75 wt% of styrene. FTIR spectroscopy revealed information about the molecular orientation upon deformation of the separate components in the triblock copolymers. Films of SBC possess a higher ductility when the semi-crystalline PCL cylindrical microdomains are quenched. In this case, the deformation proceeds via cavitation of the PCL domains and subsequent shear yielding. Long range order of the cylinders leads to embrittlement since crazes formation and crack propagation can proceed along the cylindrical axis. For the SBS triblock copolymers, a morphological transition from lamellar to short rod cylindrical microdomains was obtained by changing the casting solvent from toluene to MEK, while macroscopic orientation could be achieved by compression molding in a channel die. The toluene cast films were ductile and deformed in a homogeneous way. The MEK cast films behaved brittle as a result of crazing. Loading parallel to the lamellae results in yielding by propagation of a stable macroscopic neck.