Shape memory polyurethanes (SMPU) are one of the advanced materials that have potential applications in the field of biomedical particularly vascular stent. This paper studies the effect of incorporating palm oil polyol (POP) up to 40% molar ratio in place of petroleum-based polyol in the preparation of SMPU due to environmental concern.Polycaprolactone diol was utilized as the soft segment while 4,4′-diphenylmethane diisocyanate and 1,4-butanediol as the hard segments. The SMPU was prepared using two-step prepolymer method, and the fabricated samples were characterized to study the effect of POP on the thermal properties, tensile, and shape memory behavior of polyurethane. The results obtained have shown that SMPU with incorporation of POP showed good shape fixity (100%) and elongation at break (245%) up to 20% molar ratio of POP. The presence of dangling chains of fatty acid in POP was believed to enhance the flexibility of SMPU molecular chains by acting as a plasticizer. On the other hand, the shape recovery of SMPU remains high even at 40% molar ratio of POP, and the thermal stability of SMPU increased with the addition of POP. It is proposed that the synthesized POP-based SMPU is a suitable candidate for cardiovascular stent as they possessed desired thermal, mechanical, and shape memory properties.

Shape memory polyurethane (SMPU) with its outstanding characteristics is categorized as smart materials and has been utilized in a wide range of applications. In this study, a series of palm kernel oil polyol (PKOp) -based SMPU with the combination of polycaprolactone (PCL) and polyethylene glycol (PEG) as soft segment was synthesized and characterized for the first time. The synthesized SMPUs were examined via several techniques such as Fourier transform infrared, x-ray diffraction, thermal analysis, tensile and shape memory test. The combination of PCL and PEG in PKOp-based SMPU has overcome the drawbacks of PKOp-based PU with only PCL or PEG as soft segment. PU-PCL4PEG4 exhibited tensile strength, Young's modulus, and shape fixity of 5.7 MPa, 53.9 MPa, and 97%, respectively. For the variation of PEG molar ratio, PU-0.6PEG demonstrated good modulus (151.3 MPa) and shape fixity (99%) but its tensile strength and tensile strain at break were compromised as compared to other samples.

Muscovite clay is an ideal reinforcing filler due to its high-aspect ratio. However, it does not swell in water, making it hard to be treated and intercalated. In this study, ion exchange treatment is carried out on muscovite clay using cetyltrimethylammonium bromide (CTAB) cations via two-step intercalation method. The intercalation steps included: inorganic-inorganic ion exchange treatment and inorganic-organic ion exchange treatment under hydrothermal conditions. The intercalation of muscovite particles was examined with various techniques to analyse the physical and chemical changes. Furthermore, the hydrothermal conditions for effective CTA + ion intercalation within muscovite interlayers prepared via the hydrothermal process at low temperature, 180 • C, under different hydrothermal reaction times and CTAB/Li-Mus mass ratio were investigated. Fourier transform infra-red (FTIR) analysis revealed that the CTA + ions are diffused into the interlayers of aluminosilicate and formed a strong electrostatic bond with the clay surface. X-ray powder diffraction analysis showed that the interplanar spacing in the organo-muscovite samples is almost identical as the hydrothermal reaction time is prolonged beyond 12 h. An optimum limit of the CTAB to Li-Mus ratio is observed as the d 002 plane spacing is increased with an increase of the mass ratio of CTAB to Li-Mus up to 1.0 C and decreased with a further increase in the mass ratio. In addition, the intercalated CTA + chains are homogenously distributed and formed a paraffin-like arrangement in the muscovite clay. Besides, the structure of aluminosilicate layers is not affected or damaged after both treatments according to FTIR analysis.

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