Effects of the solubility parameter of polyimides and the segment length of siloxane block on the morphology and properties of poly(imide siloxane)

Abstract

The dependence of morphology of the poly(imide siloxane)s (PISs) on the solubility parameter of unmodified polyimides and the molecular weight and content of ␣,-bis(3-aminopropyl) polydimethylsiloxane (APPS) has been studied. The effect of the morphology on the mechanical properties is also under investigation. The domain formation in the PISs with the APPS molecular weight M n ϭ 507 g/mol is not found until the mol ratio of APPS/PIS Ն 0.5% in the pyromellitic dianhydride/p-phenylene diamine (PMDA/p-PDA)-based PISs, and at a mol ratio Ն 2.7% in the 3,3Ј,4,4Ј-benzophenone tetracarboxylic dianhydride/2,2Ј-bis[4-(3-aminophenoxy) phenyl] sulfone (BTDA/m-BAPS)-based PISs. As the APPS M n ϭ 715 g/mol, the critical APPS concentrations of the domain formation in both types of PISs are equal to 0.1 and 1.1%, respectively. The critical concentration is equal to 0.6% in the BTDA/m-BAPS-based PIS film with the APPS M n ϭ 996 g/mol. The isolated siloxane-rich phase in the BTDA/m-BAPS-based PISs becomes a continuous phase as the mol ratio of APPS/PIS Ն 7.7, 10.0, and 16.6% as the APPS M n ϭ 996, 715, and 507 g/mol, respectively. Dynamic Mechanical Analysis (DMA) shows two T g s in the PIS films having phase separation: one at Ϫ118 ϳ -115°C, being the siloxane-rich phase, the other at 181-244°C, being the aromatic imide-rich phase. The SEM micrographs show a significant deformation on the fractured surfaces of the BTDA/m-BAPS-based PIS films with a continuous siloxane-rich phase. This phenomenon of plastic deformation is also observed in the tensile tests at Ϫ118°C and at room temperature. The highest elongation in the PIS films is found at the critical siloxane content of the continuous siloxane-rich phase formation.

Structural, Thermal, Morphological, Adsorption and Catalytic Properties of Poly(BPDAH-co-ODA/PPDA)-Ag/V2O5 Nanocomposites

“…the morphology of the polymer can be altered. Jwo et al [40] reported different morphology for PI in the presence of silica and this report supported the above said statement. Thus the SEM image concluded the size, shape and morphology of the PI and its nanocomposite systems.…”

Synthesis and properties of poly(imide siloxane) block copolymers with different block lengths

“…The surface morphology of the randomly segmented copolymers has been extensively studied 13, 28, 29. However, the surface morphology of the block copolymers has not been studied.…”

“…The film surface morphologies of the randomly segmented and block copolymers under POM are shown in Figure 7 except block copolymer B‐4 due to its insolubility in CHCl 3 . Since the surface free energy of polysiloxane soft block is lower than that of polyimide hard block and the difference in solubility parameters between the polysiloxane soft block and polyimide hard block is large,29–32 the polysiloxane soft block tended to segregate to the surface and many aggregates were visible under POM. Interestingly, compared with the film surface of the randomly copolymer R‐1 , the film surfaces of the block copolymers had less but bigger aggregates, which was probably because the polysiloxane soft blocks in the block copolymers were extended.…”

Synthesis, characterization, and comparison of properties of novel fluorinated poly(imide siloxane) copolymers

“…Sumitomo Bakelite Co., Ltd., prepared, as adhesive tape, polyimides modified by aminopropyl‐terminated polydimethylsiloxane (APPS) under the trade name SIM 27. All studies conducted so far that have been related to poly(imide siloxane) have focused on the content and molecular weight of the siloxane segment and properties thereby affected, such as the mechanical, electrical, and thermal properties and surface morphology, because of the incorporation of the siloxane segment and the existence of microphase separation in the poly(imide siloxane) by thermal analysis and electron microscopy 33…”