Synergistic Effect of Hydrogen Bonds and Diffusion on the β-Crystallization of Poly(vinylidene fluoride) On Poly(methyl methacrylate) Interface

Abstract

The PVDF thin film was prepared on PMMA sublayer. Compared to the PVDF on Si wafer, the PMMA layer shows great influence on the crystallization of PVDF under quenching thermal treatment. When the PMMA layer is thinner than 90 nm, mixture of α- and β-crystals form. Pure β-crystals are obtained when the PMMA layer is around 90 nm. With further thickening of the PMMA layer, pure β-crystals always form but with a decreased crystallinity. The nanodomains and needlelike morphology of β-crystals is observed. Moreover the formation mechanism of β-phase on PMMA interface is clarified. The hydrogen bonds at PVDF and PMMA interface is formed adopting the perpendicular orientation, which serve as the key role to induce β-PVDF. The amount of β-PVDF is not only determined by the interaction of PMMA and PVDF at interface, but also the diffusion extent of PMMA into the PVDF layer.

Crystallinity and β Phase Fraction of PVDF in Biaxially Stretched PVDF/PMMA Films

“…The casting procedure led to the uniaxial stretching of the sheet, which is beneficial to the formation of β phase. Besides, the interaction between oxygen atoms of C=O groups in PMMA and hydrogen atoms of CH 2 groups in PVDF induced the formation of β crystals [ 17 ]. During preheating, the oriented molecular chains especially PMMA relaxed at a high temperature, which weakened the interaction between C=O groups and CH 2 groups, reducing the β phase fraction.…”

“…It has been well known that the addition of poly(methyl methacrylate) (PMMA) affects PVDF crystallization kinetics and more importantly alters its crystal phases [ 10 , 11 , 12 , 13 ]. The interaction between oxygen atoms of carbonyl groups in PMMA and hydrogen atoms in PVDF plays a critical role [ 10 , 14 , 15 , 16 , 17 ]. Composite fillers within PVDF matrix is also considered as another option to improve crystallinity of PVDF matrix due to the reduction in free energy barrier for nucleation [ 18 ].…”

Effect of dehydrofluorination reaction on structure and properties of PVDF electrospun fibers

“…Therefore, how to produce high content b-phase and improve its properties has always been a matter of great concern. [15][16][17][18] It is well known that copolymerization is an efficient way to produce b-PVDF with TTT conformation. The introduction of comonomers with a large steric hindrance such as triuoroethylene (TrFE), chloride triuoride ethylene (CTFE), hexa-uoropropene (HFP) and others increases the conformational potential energy of the TGTG 0 conformation chains in the aphase structure.…”

Synthesis of vinyl ester resin-carrying PVDF green nanofibers for self-healing applications

“…Figure 3 D proposes the molecular interaction between TPS and PVDF induces the formation of orientated β crystals indicates possible confirmation of hydrogen bonding at O–H … F–C due to the stronger polarity of the hydroxyl groups as observed in O–H stretching vibration in the range of 3500–3150 cm −1 37 . In addition, as investigated by Mi et al, the dipoles of β crystals relating to the peaks 1401, 1274 and 840 cm −1 are in the orthogonal direction and corresponding relative intensity can be used to determine the lattice orientation 38 . Meanwhile the interaction between C–H … F–C is a dipolar dispersion force, wherein PVDF, a non-conjugated linear fluorinated hydrocarbons and TPS also contain carbon and hydrogen resulting in transient dipole moment lead a separate transient dipole moment in neighboring molecule, initiating a fleeting attraction between the C–H molecules 39 .…”