Crystal forms and their orientation in poly(vinylidene fluoride) films prepared by an ionized-vapour deposition method

Direct Preparation of Nanoscale Thin Films of Poly(vinylidene fluoride) Containing β‐Crystalline Phase by Heat‐Controlled Spin Coating

“…Figure 2 shows the FTIR‐GIRAS of ASP and ASPAN samples prepared at temperatures below and near ambient. ASP‐10 showed a nearly complete β ‐phase, which can be identified from the peak appearing at 1 280 cm −1 16, 31–33. Upon annealing, a small and well‐distinguished peak emerged at around 1 219 cm −1 , which is correlated with the α ‐phase 12.…”

“…For the reasons above, more attention has been paid to develop a convenient method to obtain nanoscale thin films of PVDF. Previously, evaporative deposition methods – such as thermal vapor deposition,14, 15 ionized vapor deposition,16 electric‐field‐assisted vapor deposition,17 low pressure chemical vapor deposition,12 etc. – have been studied.…”

Crystalline Structure and Ferroelectric Response of Poly(vinylidene fluoride)/Organically Modified Silicate Thin Films Prepared by Heat Controlled Spin Coating

“…Only packing of PVDF molecular chains into all‐ trans β ‐crystalline lattice is not sufficient to fabricate the devices for microelectronic applications because the preferential orientation of molecular chains parallel to the plane of the substrate can alter more easily the direction of electric vectors of CF‐dipoles which can respond very sensitively to the applied electric field 39, 40, 45, 63, 64. Here, by referring to the orientation fashion of the β ‐phase crystal showing an orthorhombic unit cell6 with two all‐ trans molecular chains packed along the c ‐axis and their CF‐dipoles aligned parallel to the b ‐axis,9, 12 one can certainly understand the influence of molecular chain orientation on the electrical properties of PVDF β ‐phase, using FTIR‐GIRAS studies.…”

“…Therefore, special attention has been paid for the preparation of the nanoscale thin films of PVDF containing β ‐phase. The methods based on evaporative deposition,39–42 low‐pressure chemical vapor polymerization,43 ultrasonic atomization,44 and electro‐spray technique45 have been investigated. Recently, the spin coating based thin film fabrication methods, viz., spin coating a PVDF sol–gel,46 humidity‐controlled spin coating,47 heat‐controlled spin coating (HCSC),48 and spin coating of PVDF–metal salt [Ca(NO 3 ) 2 · 4H 2 O,49 Mg(NO 3 ) 2 · 6H 2 O,50, 51 and CaCl 2 52] composites, have elicited much interest toward realizing information storage applications because of the wide recognition gained by the spin coating technique as a cost effective method for the fabrication of microelectronic elements on the flat metal or Si‐wafer substrates in an industrial scale 47, 53…”

Exploiting physical vapor deposition for morphological control in semi‐crystalline polymer films

“…The authors further proposed a phase diagram where they claimed the crystal form to be a function of deposition rate and temperature, as illustrated in Figure . To enhance the control of dipole orientation for exhibiting piezoelectricity, thermal evaporation can also be equipped with an electric field or an ionization process . The prolonged time scale of film growth by PVD facilitates the control of chain reorientation under certain conditions, thus allowing for the achievement of strong piezoelectricity in a single step that would commonly require a multi‐step process by other means.…”