In this work, high molecular weight of heterocyclic aromatic polyimide consisting hexafluoroisopropylidene moiety in both diamine and dianhydride fragments was synthesised. The synthesis was performed via a two-step polycondensation route, which involved polyamic acid formation and chemical imidization. Subsequently, physical purification technique was conducted by microfiltration and re-crystallisation to obtain oligomers-free high molecular weight polymer. Selections of high purity and suitable solvent, type of amine catalyst, precipitation medium and reaction temperature were considered to favour the formation of high molecular weight polyimide. The synthesised polyimide was characterised by ATR-FTIR, which confirmed the presence of significant imide bands denoting the formation of imide linkage. Further confirmation of polyimide molecular structure was accomplished using 13 C and 1 H NMR. It was found that polyimide with high molecular weight (4500 KDa) was obtained with a polydispersity index of 1.48. Therefore, this polymer has favourable properties for gas separation membrane application.
) is a promising inorganic particle due to its unique crystal structure and 3-dimensional porous network. Incorporating a discrete amount of nanosized MCM-48 for material development would give significant impact to the material's performance and mechanical robustness. Thus far, the synthesis of MCM-48 in the nanoscale regime has been achieved via chemical modification techniques. However, they are often not reproducible due to limited understanding of surfactant behaviour. On the other hand, physical modification technique is more stable, thereby can reduce the possibility of producing other undesired mesophase. Nevertheless, this technique has not been adapted for nanosized MCM-48 synthesis. In this work, the physical modification technique was adapted to tailor MCM-48 particle size by varying stirring speed (i.e., 1000 rpm, 3000 rpm and 5000 rpm) and using different types of washing medium. Particle size distribution (PSD) studies showed mean particle size of 250 ± 50 nm. XRD analysis displayed several crystalline peaks indexed to cubic crystal mesophase. Transmission electron microscopy (TEM) and Brunauer-Emmett Teller (BET) analyses also showed a unique 3D cubic interconnecting porous network with specific surface area of 1030 m 2 g -1 . It was revealed that the degree of agglomeration increased as relative polarity of alcohol increased, CH 3 OH > CH 3 CH 2 OH. Therefore, particle size and agglomeration state of MCM-48 can be tailored by varying the physical modification techniques while maintaining its intrinsic pore morphology.
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