Poly(styrene-b-(ethylene-co-butylene)-b-styrene) (SEBS) triblock copolymers are promising for anion exchange membranes (AEMs), because of cost-effectiveness, C-C backbone, and natural microphase separation. Standard SEBS with low polystyrene (PS) and highly elastic poly(ethylene-co-butylene) (PEB) blocks, exhibits limited ionexchange capacity and poor dimensional stability. Herein, hydrogenating poly(styrene-b-butadiene-b-styrene) (SBS) with 86% 1,4-butadiene units turns the soft middle block into crystalline regions, improving mechanical and dimensional stability. To facilitate ion transport, methoxypolyethylene glycol (MPEG) chains are grafted onto PS blocks, quaternized with trimethylamine for cationic sites, followed by alkalization. The resulting SEBSg-PEG-x AEMs display distinct hydrophilic-hydrophobic phase separation, continuous ion-conducting channels, and enhanced physicochemical stability. The optimal SEBS-g-PEG-3 membrane shows 148.5 mScm- 1 conductivity at 80 degrees C, 20.63 MPa tensile strength, and 1572 mWcm- 2 peak power density in H2/O2 fuel cells. These findings indicate that integrating crystalline PEB domains with grafted hydrophilic MPEG chains boosts mechanical strength and ion transport, extending the applications of high-performance SEBS-based AEMs in fuel cells.

In this work, furan-terminated polystyrene (FPS) and polyisoprene (FPI) building blocks with molecular weights ranging from 3000 to 5000 were synthesized via living anionic polymerization. A series of styrene-isoprene-styrene (SIS) block copolymers with thermoreversible structures (DASIS) were then prepared through the Diels-Alder (DA) reaction between the furan groups of FPS/FPI and N,N'-(1,4-phenylene)bismaleimide (BMI). The microstructure, dynamic bond formation and thermoreversibility of the as-synthesized polymers were characterized by 1H-NMR, FT-IR, DSC and other analytical techniques. The results demonstrated that DASIS block copolymers with molecular weights of 80000–130000 were successfully fabricated. Benefiting from the unique properties of dynamic DA bonds, the precise connection of building blocks to form macromolecules was achieved at a mild temperature of 60 °C, while the efficient dissociation and recovery of building blocks were realized at an elevated temperature of 150 °C, thus enabling the flexible regulation of the monomer ratio in DASIS. With the increase in the mass fraction of the PS phase in DASIS from the initial 20

Many toughening strategies have been employed to address the inherent brittleness of epoxy resin (Ep), but at the cost of strength and modulus. Herein, a series of poly(arylene pyridine) copolymers (MTAP-X) were synthesized via superacid-catalyzed polyhydroxyalkylation and blended directly with epoxy precursors in varying ratios. Both MTAP-X copolymers and epoxy composites were characterized using 1H NMR, FT-IR, TGA, DSC, DMTA, SEM, and AFM, as well as mechanical and impact testing. The results demonstrate that the twisted aromatic molecular structures of MTAP-X, controlled by the m-terphenyl to p-terphenyl ratio, enhances both the toughness and mechanical properties of epoxy composites by increasing free volume and incorporating rigid biphenyl units. As the proportion of meta-terphenyl in triphenyls increases from 30% to 60%, MTAP-X copolymers significantly enhance the tensile strength, Young's modulus and toughness of the epoxy composites. Although further increasing the meta-terphenyl content improves toughness, it compromises the mechanical strength of the epoxy composites. At an optimal loading of 7.5 wt % MTAP-50 copolymer, the KIC, GIC, impact strength, tensile strength, and Young's modulus increase by 92.87%, 220.39%, 93.14%, 59.66%, and 46.61%, respectively, compared to pure Ep. The toughening mechanism is attributed to the ability of adjacent phenyl groups in the MTAP-X copolymers to rotate toward each other through sigma-bonds, thereby increasing free volume. Additionally, strong interfacial interactions between the pyridine ring, suspended from the polymer backbone, and the Ep contribute to the toughening effect. The rigid copolymer backbone further reinforces the epoxy network, enhancing the overall strength and durability of the Ep.

Herein, an anionic polymerization method was employed to synthesize a series of amphiphilic poly(ethylene oxide-b-styrene-b-isoprene-b-styrene-b-ethylene oxide) penta-block copolymers (OSISO). Their molecular structure and properties were comprehensively characterized using GPC,H-1-NMR, thermodynamic rheological testing and water contact angle test. Notably, the hydrophilic characteristics exhibited a proportional increase with the rise in poly(ethylene oxide) (PEO) content, ranging from 1.3 to 12.6 wt%. The polystyrene blocks with low number-average molecular weight (2000-3500) reduced the copolymer melt viscosity, surpassing a tenfold decrease than the control sample within the temperature range of 50-150 degrees C. Resultantly, this series of OSISO copolymers could be used to develop amphiphilic hot-melt pressure-sensitive adhesives (HMPSAs) by low temperature hot-melt processing method (<120 degrees C). HMPSAs loaded with 2 wt% of geniposide, prepared by an optimized composition formula of OSISO copolymers, tackifiers, and plasticizers (in a ratio of 5:5:2), displayed excellent in vitro drug release performance. Additionally, these adhesives presented impressive 180 degrees peeling strength (0.05-0.14 kN/m) without residues left on the substrate in the 180 degrees peeling tests. The incorporation of PEO block significantly enhanced both the adhesive properties and accumulative drug release. Geniposide showed a burst release behavior with a moderate accumulative drug release (15-30 wt%), attributed to the PEO phase without crystallization behavior of long PEO chains.

Poly(styrene-b-(ethylene-co-butadiene)-b-styrene) copolymers (SEBS) have garnered significant attention to develop anion exchange membranes (AEMs) for fuel cells. However, SEBS commodities encounter a formidable obstacle of fabricating high-performance AEMs as thermoplastic elastomer. Herein, a series of poly(styrene-bbutadiene-b-styrene) copolymers (SBS) with high content of 1,4-butadiene units (>90 % of middle block) and variable content of polystyrene (PS, 51.3, 61.6 and 70.7 wt%) has been designed to develop SEBS AEMs with high-strength polyethylene phase via hydrogenation, chloromethylation, quaternization and alkalization. The results demonstrate that high PS content broadens the ion transport channel, improves the ion exchange capacity (IEC) and alkali resistance stability, and substantially boosts the ion conductivity, water uptake and swelling ratio of AEMs. Besides, the high proportion of polyethylene phase from 1,4-butadiene unit of SBS copolymers provides good dimensional stability to the AEMs. Remarkably, the AEMs with 70.7 wt% PS and an IEC value of 3.37 mmol g(-1) significantly upgrades the ionic conductivity to -190 mS cm(-1) at 80 degrees C. It attains a peak power density of -1000 mW cm(-2) at 2.09 A cm(-2) in a H-2/O-2 single cell operating at 80 degrees C. This outstanding performance underscores the promising potential of such SEBS copolymers in the development of high-performance SEBS AEMs for fuel cells.

The effects of grafting level of polyethylene glycol (PEG) grafted styrene ethylene propylene styrene (SEPS) on the intrinsic brittleness of epoxy thermosets were studied. The SEPS-g-PEG block copolymer (BCP) was synthesized by grafting various grafting degree of PEG (i.e., 10%, 20%, 30%, and 40%) on polystyrene (PS) blocks of SEPS following Williamson ether synthesis method. A total of 10 wt% of the BCP modifiers were dispersed in epoxy thermosets. PEG side chains were miscible in the epoxy which formed a uniform BCP dispersion within the epoxy thermoset matrix. As the degree of PEG grafting was increased, the BCP phase was absorbed in the epoxy matrix. This absorption occurred because the increase in PEG grafting provided more miscible PEG chains to bind the BCP and epoxy nanostructures together. The differential scanning calorimeter and dynamic mechanical thermal analysis analyses indicated that BCP toughened epoxy exhibited an improved glass transition temperature (Tg). At a 40% PEG grafting degree in the BCP, the critical stress intensity factor (KIC) and critical strain energy release rate (GIC) increased up to 80% and 180%, respectively. This trend suggested that the energy associated with fractures could be absorbed through the deformation of the softer phases when a load was applied to them. Mechanical tests of pure epoxy and toughened Epoxy/SEPS-g-PEGx image

Through anionic two-stage polymerization, block-type styrene-butadiene rubber (SSBR) with systematically regulable low-temperature loss peaks is successfully prepared. The influence of 1,2-Bd unit in the soft segment of block-type SSBR on mechanical properties, dynamic mechanical properties, and microscopic morphology is studied, while pressure factors are introduced into dynamic mechanical studies. The block-type SSBR with a soft segment containing 21.9 wt% of 1,2-Bd exhibits the highest tensile strength, elongation at break, and tear strength. Under atmospheric pressure, the soft segment 1,2-Bd unit influences the dynamic mechanical properties by altering the chain segment's motion loss capability. As the mass fraction of 1,2-Bd increases from 21.9 to 58.6 wt%, tan delta max increases, the glass transition temperature of the soft segment increases from -59.0 to -18.9 degrees C. Additionally, influenced by thermodynamic compatibility, the microscopic morphology transitions from strong separation to weak separation. Pressure affects dynamic mechanical properties by altering the free volume of the chain segments. Pressure reduces tan delta max, increases Tg, and raises the average Tg of the soft segment by 11 degrees C. The K value of the linear equation representing the relationship between the soft segment Tg and the mass fraction of 1,2-Bd is unaffected by pressure. The binary block-type styrene-butadiene rubber (SSBR) has been synthesized using butadiene (Bd) and styrene (St) as monomers through living anionic polymerization. Our focus is on exploring the correlation between the structure and dynamic mechanical properties of block-type SSBR under normal and high-pressure conditions. The effect of the phase structure and pressure of block-type SSBR on the dynamic mechanical properties was clarified. image

A series of star-shaped multi-arm styrene-butadiene copolymers (S-g-SSB-6) were synthesized by living anionic polymerization, with n-butyllithium as initiator, styrene and butadiene as monomers, 2,2-di(tetra-hydrofuran-2-yl) propane as polar structure regulator and hexachlorodisilane as coupling agent. The molecular weight and its distribution, coupling arm number and coupling efficiency of S-g-SSB-6 were characterized by gel permeation chromatogram. The rheological properties of S-g-SSB-6, star-shaped multi-arm styrene-butadiene copolymer with SiCl4 as coupling agent, and linear styrene-butadiene copolymer (L-SSB) were characterized by rotational rheometer, and the effects of branched chain length and branched chain flexibility on the rheological properties of S-g-SSB-6 were also investigated. The results showed that the coupling arm numbers of S-g-SSB-6 reached 4.1, and the coupling efficiency was greater than 80%. S-g-SSB had lower melt viscosity and better fluid flow than those of L-SSB under the same weight-average molecular weight. When the branching degree was the same, the melt viscosity of S-g-SSB-6 increased with the increase of single arm molecular weight and molecular chain rigidity.

Owing to structure advantages, poly(styrene-b-(ethylene-co-butylene)-b-styrene) (SEBS) has garnered significant attention in the field of anion exchange membranes (AEMs) for fuel cell applications. However, its low ionic conductivity has remained a formidable obstacle for high-performance SEBS based AEMs. Herein, an innovative approach is employed, incorporating ionic oligomeric polystyrene (OPS) into physically crosslinked SEBS based AEMs, to fabricate two series of OPS/SEBS AEMs via precise control of the molecular weight and load ratio of OPS, respectively. The variables are theoretically capable of decreasing the glass transition temperature (Tg) of the polystyrene phase below the operating temperature of fuel cells. The results demonstrate that the lower molecular weight and the higher load quantity of OPS not only broaden the ion transport channels but also lower the energy barrier of the conducting polystyrene phase. Remarkably, the membrane (1300-CHM-OH-35) with an IEC of 2.41 mmol g- 1 significantly improved the ionic conductivity to 150.9 mS cm-1 at 80 degrees C, despite its low total polystyrene content (45.78%), and attained a peak power density of 506.26 mW cm-2 at 1100 mA cm-2 in a H2/O2 single cell operating at 70 degrees C. This outstanding performance underscores the promising potential of our approach in the development of high-performance SEBS AEMs for fuel cell applications.

采用阴离子聚合方法,以双锂引发剂引发异戊二烯聚合并以2-((环氧乙烷-2-基甲氧基)甲基)呋喃(FGE)为封端剂制备双末端含呋喃基团的聚异戊二烯.利用核磁共振和红外光谱对呋喃官能化聚异戊二烯的封端效率进行检测;利用凝胶渗透色谱、基质辅助激光解吸电离飞行时间质谱和差示扫描量热仪对其相对分子质量及分布和热性能进行分析.结果表明,官能化封端效率大于95%;聚异戊二烯的分子量分布指数(PDI)为1.07(<1.1),符合活性阴离子聚合窄分布的特点;由于聚异戊二烯的1,4-结构含量较低且链端存在的呋喃环使得内旋转位阻增大,双端呋喃官能化聚异戊二烯的玻璃化转变温度比未封端的略有升高.这种高效呋喃封端方法为构建理想动态交联网络的橡胶材料提供了新的途径.

采用活性阴离子聚合方法,以四氢呋喃(THF)/环己烷(CYX)为溶剂、正丁基锂为引发剂,苯乙烯与4-叔丁氧基苯乙烯为单体合成4-叔丁氧基苯乙烯-苯乙烯共聚物,并表征了其结构与性能.结果表明:-78℃,THF为溶剂时,4-叔丁氧基苯乙烯-苯乙烯共聚物相对分子质量分布指数(PDI)为1.23,共聚过程中4-叔丁氧基苯乙烯活性高于苯乙烯;m(THF)∶m(CYX)=5∶5的THF/CYX为溶剂,-30℃下所得4-叔丁氧基苯乙烯-苯乙烯共聚物的PDI为1.10,相对分子质量分布更窄且有利于降低聚合成本;4-叔丁氧基苯乙烯-苯乙烯共聚物的玻璃化转变温度(tg)均低于4-叔丁氧基苯乙烯均聚物,4-叔丁氧基苯乙烯含量越高,4-叔丁氧基苯乙烯-苯乙烯共聚物的tg越高.

以正丁基锂(n-BuLi)为引发剂,2,2-二(5-甲基-2-四氢呋喃基)丙烷(BMTFP)、乙基四氢糠基醚(ETE)、双四氢糠丙烷(DTHFP)为极性调节剂,在不同调节剂用量及聚合温度下进行丁二烯-苯乙烯的阴离子共聚合反应.利用1HNMR和GPC对丁苯共聚物的微观结构、相对分子质量及其分布进行了表征和测试.结果表明,BMTFP聚合体系中无副反应发生,共聚物相对分子质量分布较窄,符合活性阴离子聚合的特点;BMTFP对丁苯共聚物具有较强的微观结构调节能力,在聚合温度为50℃、n(BMTFP):n(n-BuLi)=2.0:1.0时,丁苯共聚物中1,2-结构相对含量可以达到69.7％,苯乙烯微嵌段含量趋近于0.且在相同条件下,BMTFP与ETE、DTHFP对丁苯共聚物微观结构的调节能力处于同一水平,但BMTFP的合成中所需的主要原料来源于生物基平台化合物,从环境保护、能源安全以及潜在的经济价值等方面考虑,BMTFP在制备高乙烯基溶聚丁苯橡胶方面具有良好的发展前景.

Silicon dioxide (SiO2), commonly known as silica, the surface is modified using bis(3-triethoxysilylpropyl) tetrasulfide, also known as (Si69) and polyethylene glycol (PEG). A series of composites are prepared by mixing general solution styrene butadiene rubber (GSSBR) and polyethylene oxide-functionalized solution styrene butadiene rubber (FSSBR) with unmodified and modified SiO2. A comparative analysis is conducted using various characterization techniques to evaluate the performance of different composites regarding rubber-filler dispersion, thermal and dynamic mechanical properties. Field emission scanning electron microscopy demonstrates that FSSBR/SiO2@Si69 facilitates a more uniform and well-dispersed distribution of silica particles, improving the compatibility between the rubber-filler matrix and reducing the size of particle aggregates. Thermogravimetric analysis shows that composites GSSBR/SiO2@PEG and GSSBR/SiO2@Si69 + PEG and FSSBR/SiO2@Si69 possess superior thermal stability with minimal weight loss. According to the rubber process analyzer (RPA) analysis, FSSBR/SiO2@Si69 results in significantly reduced Payne effect values, indicating improved dispersion of the rubber-filler mixture. These findings suggest that the simultaneous functionalization of SSBR and surface modification of SiO2 effectively enhance the interaction between filler and rubber.

Poly(styrene-b-(ethylene-co-butylene)-b-styrene) copolymer (SEBS) has been widely used for anion exchange membranes (AEMs). However, it is still challenging to improve the dimensional stability of SEBS based AEMs because their main component poly(ethylene-co-butylene) phase (PEB) is rubbery. To this end, chemical crosslinking is widely built within the polystyrene phase (PS), but which still makes the PEB phase contribute nothing to the dimensional stability and ionic conductivity. Herein, we attempt to synthesize poly(styrene-b-butadiene-b-styrene) copolymers (SBS) owning adjustable content of 1,4-butadiene units via living anionic polymerization, following with hydrogenation. As more 1,4-butadiene units are copolymerized into SBS, the PEB phase becomes even harder, which significantly enhances the comprehensive performance of AEMs. The AEMs intentionally maximized by this approach not only have ultrahigh dimensional stability (i.e. 23.2 ± 0.1 of WU, 3.8 ± 0.1 of SR at 30 °C, nearly no change within 30 ~ 80 oC), but also exhibit a comparable hydroxide conductivity (~ 85 mS cm−1 at 80 °C with IEC as 1.06 ± 0.05 mmol/g). The membrane electrode assembly made from such AEM has a peak power density 370 mW cm−2 at a current density of 800 mA cm−2. This work provides a straightforward approach for fabricating long term alkaline durable and mechanically stable SEBS based AEMs, suitable for fuel cells application.

The dynamic mechanical properties of the viscoelastic polymer materials are usually considered to be the key parameters for the vibration damping or acoustic materials. The relationship between the molecular structures of the random copolymer butadiene styrene rubber (SBR) obtained through the anionic polymerization method and their dynamic mechanical parameters under high pressure is studied to explore the energy loss mechanism of the polymer materials applied in the special conditions such as high pressure. The dynamic mechanical parameters were tested though experimental methods with pressure chambers, which can supply high pressure to the polymer samples. The results show that the most important effect factor of the molecular structure is the ratio of the content of the stiffer segments composed of styrene in the SSBR molecular chain to the softer ones composed of 1, 4-butadiene. This can be attributed to the stiffer segments supplying bigger free volumes for the molecular motion and higher modulus to resist to the high pressure, and the softer segments endue the effective energy loss ability to the polymer chains. However, the mass ratio of the stiffer and softer segments should be in an appropriate range, which the content of the styrene must be less than 40%.

Block solution-polymerized styrene-butadiene rubber (SSBR) with two different compositions and ratios was designed and synthesized by living anionic polymerization with styrene and butadiene as monomers, n-butyllithium as initiator, 2,2-bis(tetrahydrofuran)propane as modifier, and cyclohexane as solvent. The microstructure, chemical composition and molecular weight and its distribution of the block SSBR were characterized by proton nuclear magnetic resonance spectrometer and gel permeation chromatographer, and the mechanical properties and dynamic mechanical properties of the block SSBR vulcanizate were analyzed by rubber tension machine and dynamic mechanical analyse respectively. The results showed that the molecular structure of the block SSBR met the desired molecular structure. The vulcanizate had good mechanical properties and dynamic mechanical properties. The higher the mass ratio of the soft block to the hard block of the block SSBR, the wider the damping temperature range. As the soft block had lower bound styrene content, the damping temperature range of the block SSBR was more widened. When mass fraction of bound styrene of the two blocks of block SSBR was 15% and 50%, and the mass ratio was 7/3, the efficient damping temperature range exceeded 53 ℃ with loss factor of not less than 0.3.

Hybrid anion exchange membranes (AEMs) were prepared via chemically functionalizing and crosslinking poly(styrene-b-[ethylene-co-butylene]-b-styrene) (SEBS) copolymers and low molecular weight homo-polystyrene (hPS). Via sequential chloromethylation, crosslinking, quaternization, and alkalization, a series of hPS/SEBS AEMs were obtained with varying content of hPS. Systematic structural, morphological, mechanical, absorption, and transport measurements reveal that these properties depend on the total PS content in the membranes. Particularly, increasing total PS content causes (a) PS domains in the AEMs transition the cylindrical morphology to lamella-like morphology with comparable correlation length; (b) Young's modulus, water uptake, swelling ratio, ionic exchange capacity and ionic conductivity of the AEMs, and T-g of PS phase increase. In addition, the alkaline stability of the hPS/SEBS AEMs is also improved by addition of hPS. These findings suggest that the proposed method can develop high performance SEBS AEMs that are suitable for fuel cell applications.

A series of polystyrene macromonomers were synthesized by living anionic polymerization technique using styrene as monomer and p-vinylbenzyl chloride as capping agent.The star-branched styrene-butadiene-styrene (S-g-SBS) copolymer with ordered polystyrene as side chains was designed and synthesized using butadiene and polystyrene macromonomer as monomers and divinyl benzene as coupling agent.The chemical constitution and microstructure of polystyrene macromonomers and S-g-SBS were characterized by proton nuclear magnetic resonance spectrometer, gel permeation chromatographer and differential scanning calorimeter, and the rheological properties of S-g-SBS were analyzed by rotational rheometer.The results showed that polystyrene macromonomers with controlled molecular weight and narrow molecular weight distribution were obtained.The content of 1,2-structure of polybutadiene in S-g-SBS could be regulated between 30% and 70%, and the lower the content of 1,2-structure, the lower the melt viscosity.For the similar molecular structural parameter, the melt viscosity of S-g-SBS was obviously lower than that of linear SBS.

以过氧化苯甲酰(BPO)为引发剂,2,2,6,6-四甲基哌啶-1-氧基自由基(TEMPO)为自由基捕捉剂,进行3种低相对分子质量模型聚丁二烯,即高乙烯基聚丁二烯橡胶(HVPB)、高反式聚丁二烯橡胶(HTPB)及高顺式聚丁二烯橡胶(HCPB)的自由基接枝反应,并利用傅里叶变换红外光谱和核磁共振氢谱对模型聚丁二烯接枝产物的微观结构、TEMPO及BPO残基的含量进行了分析.结果表明,聚丁二烯的自由基接枝反应初期主要以夺氢反应为主,随着反应时间的延长,自由基加成反应占比增加,增加幅度由高到低依次为HCPB、HVPB、HTPB.聚丁二烯的1,2-结构有利于夺氢反应,而加成反应更易在顺式1,4-结构上进行.