end capped whereas cyclic polymers prepared via LCP method cannot be end capped with functional groups, LAP results in more thermally stable polymers. It has a much lower PDI ranging between 1.3 and 1.9 as opposed to PPA synthesized through LCP which has a PDI ranging between 2 and 4.5. This is because of the ability to control the character, molecular weight, and end group of the polymer. Furthermore, the initiator used in LAP synthesis method, which is a strong nucleophile, acts as the first endcap, and hence by controlling the amount of initiator used, a control over the molar mass and PDI can be obtained. This is in contrary to cyclic PPA which is synthesized through LCP where the initiator (Lewis acid) will not be part of the final PPA product, and hence, controlling the amount of Lewis acid used will have no to little effect on the final molar mass and PDI of cyclic PPA polymer. Coordinative polymerization (CP) Although a less known polymerization technique, coordinative polymerization has been used a few times in PPA preparation. It mostly requires the activation of transition metal catalysts with trimethylaluminum or diethyl aluminum chloride and allows a control over the stereoselectivity of the compound. Another advantage of this technique lies within the usage of water as a co-catalyst in PPA synthesis which is deemed impossible in other polymerization methods. Professor Hisaya Tani from the Department of Polymer Science at Osaka University was the first to report a stereospecific polymerization of o-phthalaldehyde by employing dimeric dimethylaluminumoxybenzylideneaniline [Me2AlOCMeNPh]2 as catalyst and water as a co-catalyst. He was able to synthesize a fibrous PPA in exclusively trans-configuration which had never been reported before. Nonetheless, due to the inability to endcap the polymer with functional groups, this technique is rarely utilized at present and the mechanism of formation of PPA remains ambiguous and not well studied. Types of poly(phthalaldehyde) Depending on the polymerization technique applied, two different types of poly(phthalaldehyde) can be acquired, linear and cyclic (see Figure 1). In this section, the properties and characteristics of each type will be thoroughly depicted. Linear PPA Linear PPA is produced by anionic polymerization methods using a strong nucleophile as an initiator. This technique prevents the cyclization of the polymer chain as the propagating species have only one charged terminus that cannot backbite the other terminus which, in turn, is neutral in charge. Although processing linear PPA