Effect of methoxy position on dynamic mechanical and shape memory properties of methoxyphenol-based polybenzoxazines

Abstract

Two series of benzoxazines were synthesized from o-, m-, and p-methoxyphenols, two polyetheramines with different molecular weights, and formaldehyde. The glass transition temperatures (T _gs) of m-methoxyphenol-based polybenzoxazines are respectively higher than those of o- and p-methoxyphenol-based counterparts. The polybenzoxazines exhibit thermally induced one-way dual-shape memory behavior based on T _g, and the o- and p-methoxyphenol-based polybenzoxazines exhibit higher shape memory performance than m-methoxyphenol-based counterparts under motion constraints.     

Functionalized electrospun mats from styrene-maleic anhydride copolymers for immobilization of acetylcholinesterase

A series of electrospun mats of styrene-maleic anhydride copolymers has been functionalized by modification with two types of spacers - a polymer with a flexible hydrophilic polyether chain (Jeffamine® ED) and a rigid low-molecular-weight spacer (р-phenylenediamine). The successful modification of the microfibrous mats with these bifunctional compounds has been proved by ATR-FTIR and X-ray photoelectron spectroscopy (XPS) analyses. In a further step, acetylcholinesterase (AChE) has been covalently immobilized onto the modified mats using glutaraldehyde as a binding agent. The amount of bound protein and the specific activity of the immobilized AChE have been determined. The highest activity has been displayed by AChE covalently bound to Jeffamine-modified microfibrous mats. Moreover, the immobilized AChE is characterized by enhanced thermal and storage stability as compared to the free enzyme.     

Jeffamine聚醚胺改性合成介孔及超微孔氧化硅微球

通过对Jeffamine ED2003进行硬脂酸接枝,获得了一种在水溶液中能够进行自组装的新型聚醚酰胺高分子表面活性剂,命名为ED2003-fa-18。以ED2003-fa-18聚醚酰胺高分子表面活性剂为模板,以正硅酸乙酯(TEOS)为无机硅源,在酸性条件下水热合成了介孔及超微孔氧化硅微球。利用粉末X射线衍射(XRD)、N₂物理吸附、红外光谱(IR)、核磁共振波谱(¹H NMR)、扫描电镜(SEM)和透射电镜(TEM)等方法对合成样品进行了表征。研究结果表明,通过改变合成体系中表面活性剂的浓度,可控合成出了有序的介孔及超微孔氧化硅材料。当ED2003-fa-18的浓度为1wt%时,合成的材料为介孔氧化硅,样品的最可几孔径约为2.2nm。当ED2003-fa-18的浓度从3wt%增加到7wt%时,样品的最可几孔径从1.98nm减小到1.94nm,得到的样品为超微孔氧化硅材料。样品的比表面积在500m²·g^-1左右,孔体积在0.3cm³·g^-1左右。由SEM照片可知,所合成的介孔及超微孔氧化硅材料均为由20~30nm的球形纳米颗粒进一步团聚形成的2~4μm的紧密堆积的实心微球。     

Amino-terminated poly(ethylene glycol) as the initiator for the ring-opening polymerization of 3-methylmorpholine-2,5-dione

Block copolymers with poly[3-methylmorpholine-2,5-dione] (PMMD) and poly[ethylene glycol] (PEG) blocks, PMMD-b-PEG-b-PMMD, were synthesized via ring-opening polymerization of 3-methylmorpholine-2,5-dione with amino-terminated PEG as the initiator at 140 °C within 10 h. Three kind of amino terminated PEG with different average molecular weight were used. The block copolymer was amorphous and the glass transition temperature decreased with increase of PEG block in the copolymer.     

Synthesis and characterization of new polyamideimides with a highly flexible soft block

Five new polyamideimides (PAI) were synthesized from five diacid chlorides with preformed imide rings and a telechelic α,ω-diamino-polyoxyethylene (Jeffamine JFA ED600). The diacid chloride monomers could be obtained in high yields (77–92%) from chlorinating the corresponding diacids which were obtained from the reaction of trimellitic anhydride with aromatic diamines (1,4-phenylene diamine; 2,2-bis(4-aminophenyl)methane; 2,2-bis(4-aminophenyl)propane; 4,4′-oxydianiline and 1,1-bis(4-aminophenyl)cyclohexane). The telechelic monomers were characterized by FTIR and ¹H-NMR. After a few preliminary experiments aimed at optimizing the polymerization conditions for particularly poorly soluble diacid chlorides, five new PAI were synthesized with inherent viscosities in the range of 0.35–0.65 dL/g. Their characterization by transmission FTIR and by advanced NMR techniques, including heteronuclear 2D NMR, fully confirmed their chemical structure as shown by the complete assignments of their ¹H and ¹³C-NMR spectra. Compared with other PAI described in the literature, these polymers proved to be much more sensitive towards polar organic solvents even showing significant solubilities in chloroform and tetrahydrofuran. These materials enabled the casting of transparent films which were very tough in the dry state. However, and as further evidenced by a DSC investigation, their phase separation is usually not sufficient to provide a very strong physical crosslinking by the aggregation of the polymer hard blocks. Consequently, their physical crosslinking would have to be significantly improved for preventing the material failure in highly solvating media and open the way for new performances in membrane separation systems. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 2873–2889, 1999     

Layered silicate/epoxy nanocomposites: synthesis,characterization and properties

Novel epoxy‐clay nanocomposites have been prepared by epoxy and organoclays. Polyoxypropylene triamine (Jeffamine T‐403), primary polyethertriamine (Jeffamine T‐5000) and three types of polyoxypropylene diamine (Jeffamine D‐230, D‐400, D‐2000) with different molecular weight were used to treat Na‐montmorillonite (MMT) to form organoclays. The preparation involves the ion exchange of Na⁺ in MMT with the organic ammonium group in Jeffamine compounds. X‐ray diffraction (XRD) confirms the intercalation of these organic moieties to form Jeffamine‐MMT intercalates. Jeffamine D‐230 was used as a swelling agent for the organoclay and curing agent. It was established that the d₀₀₁ spacing of MMT in epoxy‐clay nanocomposites depends on the silicate modification. Although XRD data did not show any apparent order of the clay layers in the T5000‐MMT/epoxy nanocomposite, transmission electron microscopy (TEM) revealed the presence of multiplets with an average size of 5 nm and the average spacing between multiplets falls in the range of 100 Å. The multiplets clustered into mineral rich domains with an average size of 140 nm. Scanning electron microscopy (SEM) reveals the absence of mineral aggregate. Nanocomposites exhibit significant increase in thermal stability in comparison to the original epoxy. The effect of the organoclay on the hardness and toughness properties of crosslinked polymer matrix was studied. The hardness of all the resulting materials was enhanced with the inclusion of organoclay. A three‐fold increase in the energy required for breaking the test specimen was found for T5000‐MMT/epoxy containing 7 wt% of organoclay as compared to that of pure epoxy. Copyright © 2004 John Wiley & Sons, Ltd.     

Jeffamine聚醚胺改性合成介孔及超微孔氧化硅微球

通过对Jeffamine ED2003进行硬脂酸接枝,获得了一种在水溶液中能够进行自组装的新型聚醚酰胺高分子表面活性剂,命名为ED2003-fa-18.以ED2003-fa-18聚醚酰胺高分子表面活性剂为模板,以正硅酸乙酯(TEOS)为无机硅源,在酸性条件下水热合成了介孔及超微孔氧化硅微球.利用粉末X射线衍射(XRD)、N₂物理吸附、红外光谱(IR)、核磁共振波谱(¹H NMR)、扫描电镜(SEM)和透射电镜(TEM)等方法对合成样品进行了表征.研究结果表明,通过改变合成体系中表面活性剂的浓度,可控合成出了有序的介孔及超微孔氧化硅材料.当ED2003-fa-18的浓度为1wt%时,合成的材料为介孔氧化硅,样品的最可几孔径约为2.2 nm.当ED2003-fa-18的浓度从3wt%增加到7wt%时,样品的最可几孔径从1.98 nm减小到1.94 nm,得到的样品为超微孔氧化硅材料.样品的比表面积在500 m²·g^-1左右,孔体积在0.3 cm³·g^-1左右.由SEM照片可知,所合成的介孔及超微孔氧化硅材料均为由20~30 nm的球形纳米颗粒进一步团聚形成的2~4 μm的紧密堆积的实心微球.