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Abstract: This work describes the synthesis and comparative shape memory properties of cross-linked networks derived from epoxy and cyanate ester monomers containing polyether oligomers as reactive shape memory segments. The hydroxy telechelic oligomers viz. polyethyleneglycol (PEG), polypropyleneglycol (PPG), and polytetramethyleneglycol (PTG) are reacted with epoxy–cyanate ester matrix resulting in shape memory polymers with high transition temperatures. The soft oligomer segments act as flexible linker unit which interconnect oxazolidone, isocyanurate and triazine ring structures in the cross-linked polymer. The resultant cyclomatrix SMPs exhibit high transition temperatures 132, 178 and 161°C respectively for PEG, PPG and PTG integrated SMPs. The Eg /Er ratios are increased in the order PEG98% with recovery time <100s. All the SMPs display good thermal stabilities (both inert and oxidative) above 275°C. [Copyright &y& Elsevier]

Abstract: This review analyses the progress in the field of shape memory epoxy resins (SMEPs). Partial crystallisation and vitrification are the basis of shape memory effect in SMEPs. Several synthetic approaches for SMEPs, their composites and foams have been reviewed. Strategically incorporated thermally reversible segments induce the shape memory effect in epoxy resins. By varying the nature and concentration of shape memory segments, wide range of shape memory properties and transition temperatures (shape memory temperatures) can be achieved. Triple shape memory, self-healability and electroactive capability are some of the additional features that can be created in SMEPs. Among the thermoset resins, shape memory epoxies are the most attractive systems because of the ease of processability, composite forming properties and dimensional stability. Shape memory epoxy polymers that can be processed into elastic memory composites are candidate materials in the processing of many smart engineering systems. In this background, a review consolidating the progress in SMEP has contemporary relevance. The present article takes a stock of the trend in SMEP with a view to assess the direction of future initiatives in this area. It is concluded that there is tremendous scope for research leading to technological evolution in the field of SMEP. [Copyright &y& Elsevier]

Poly(ethylenimine) was grafted on the magnetite (Fe 3 O 4) nanoparticles, and subsequently reacted with different aldehydes to form the imine functionalities (Fe 3 O 4 -Imine NPs). Thus formed Fe 3 O 4 -Imine NPs could host copper salts generally used as the homogeneous catalyst in organic reactions with the stability prerequisite for the recycling. The expected chemical structures of Fe 3 O 4 -Imine NPs were ascertained by the FTIR and CHNS analyses. The physical structure of Fe 3 O 4 -Imine NPs was found to be corn-like assemblies from the images obtained by FESEM and HRTEM. The Fe 3 O 4 -Imine NPs assemblies possessed the superparamagnetic properties which made possible to withdraw these particles from the reaction solution efficiently. The copper salt loading capacity of the Fe 3 O 4 -Imine was lower than that of the Fe 3 O 4 -PEI, but the water content in the Fe 3 O 4 -Imine was higher (10 wt%) than that of the Fe 3 O 4 -PEI (2.5 wt%). Among different aldehydes and copper salts used, the Fe 3 O 4 -Imine formed by benzaldehyde and loaded with copper acetate salt exhibited better catalytic activity in the Henry reactions using water as the solvent. Also, the Fe 3 O 4 -Imine showed better catalytic activity than that obtained using the Fe 3 O 4 -PEI in both Henry reactions and A3-coupling of aldehyde, pyrrolidine, and phenyl acetylene reactants. The several representative examples of these coupling reactions were studied to understand the different parameters affecting the catalytic efficacy of copper acetate loaded Fe 3 O 4 -Imine. [Display omitted] • PEI-grafted magnetite NPs were reacted with aldehydes to form imine functionality. • The physical structure of Fe 3 O 4 -Imine NPs was found to be corn-like assemblies. • Fe 3 O 4 -Imine-Cu(II) was studied for catalyzing Henry and A3-coupling reactions. • Fe 3 O 4 -Imine-Cu(II) exhibited better catalytic activity for the Henry reaction in water. • Fe 3 O 4 -Imine-Cu(II) catalyzed multicomponent couplings in the absence of solvent. [ABSTRACT FROM AUTHOR]

In the present work, polybenzimidazole (PBI) containing aliphatic (cyclohexane based, ARB-0, I.V. = 1.5 dL/g) and aromatic (terephthalic acid based, ARB-100, I.V. = 3.46 dL/g) backbones were synthesized. On blending the two polymers, PBIs with tunable mechanical and proton conductivity were achieved. ARB-0 exhibited proton conductivity of 114 mS/cm whereas ARB-100 marked a high value of 220 mS/cm at 160 °C. ARB-100 resulted in high tensile modulus of 11 GPa meanwhile ARB-0 exhibited 2 GPa only. The corresponding elongations were 2 and 27% respectively. The aliphatic-aromatic blends resulted in good elongation, modulus and conductivity. The aromatic rich blend composition (ARB-67) displayed maximum proton conductivity (240 mS/cm) and morphology exhibited local ordering behavior due to aliphatic-aromatic intra-chain interactions. [ABSTRACT FROM AUTHOR]