Polymerization of Vinylidene Fluoride in Supercritical Carbon Dioxide:  Effects of Poly(dimethylsiloxane) Macromonomer on Molecular Weight and Morphology of Poly(vinylidene fluoride)

Abstract

The batch homopolymerization of vinylidene fluoride (VDF) in supercritical carbon dioxide (scCO2) was studied using diethyl peroxydicarbonate (DEPDC) as a free radical initiator. Experiments were carried out to investigate the effects of monomer concentration, initiator concentration, and agitation. It was shown that poly(dimethylsiloxane) monomethacrylate (PDMS-ma) acts effectively as a stabilizer influencing both the morphology and the molecular weight of the poly(vinylidene fluoride) (PVDF) product. Scanning electron microscopy (SEM) and laser scattering particle size analysis were employed to characterize polymer particle morphology and particle size distribution. Thermal analysis of the products by differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA) is also reported. 19F nuclear magnetic resonance (NMR) was performed to characterize the microstructure of the PVDF polymer chain.

The Synthesis and Crystallization of Poly(vinylidene fluoride) in Supercritical CO2

“…The H-H defect units appear at the chemical shifts -113 ppm and 116 ppm (peaks D and E in Figure 1). The H-H defect concentrations of typical commercial PVDF varies 3~6% [14]. The value of the sc-PVDFs are about 4.0%, and that of ordinary PVDF (o-PVDF) obtained from the emulsion polymerization is 5.6% (Table 1).…”

“…They set up an extended homogeneous kinetic model predicting the polydispersities of PVDF reasonably well [10]. Very recently, Howdle et al have studied the effects of stabilizers on dispersion polymerization of VDF in sc-CO 2 and obtained high molecular weight products with well-defined and uniform spherical particles [14][15][16]. However, the influence of sc-CO 2 on the crystallization behaviors of PVDF has never been investigated up to now.…”

Putting the fizz into chemistry: applications of supercritical carbon dioxide in tissue engineering, drug delivery and synthesis of novel block copolymers

“…At Nottingham, free-radical dispersion polymerizations in scCO 2 were investigated with the focus on developing a variety of stabilizers [38][39][40][41][42]. The synthesis of biomaterials in scCO 2 has drawn our particular attention.…”

High molecular weight graft stabilisers for dispersion polymerisation of vinylidene fluoride in supercritical carbon dioxide: the effect of architecture

“…Polymerisations were carried out in a 60 ml stainless steel autoclave [24] at 55 8C, with stirring at 100 rpm, an initial vessel pressure of 4000 psi (27.21 MPa), concentration of VDF monomer [M] as 9.8 mol/l, concentration of initiator [I] as 1.5 mmol/l, and concentration of stabiliser [S] as 0.52 wt% (weight/weight relative to VDF monomer). In all cases, the reactions were deliberately terminated when the pressure in the autoclave fell by 300 psi (2.04 MPa); the point at which we found that the solid contents in autoclave approaches ca.…”

“…A tacky solid copolymer was obtained while the copolymer contained less than 23 mol% VDF. We have reported elsewhere that commercially available PDMS monomethacrylate (PDMSma) has a clear effect on the homopolymerisation of VDF in scCO 2 , leading to a high molecular weight product with a broad molecular weight distribution (MWD), and primary particles (200-500 nm) that coagulate to form larger uniform coarse particles (200-500 mm) [24]. Recently, we reported that a fluorinated graft poly(methyl vinyl ether-alt-maleic anhydride) (F-g-PMVE-MA) was an effective stabiliser for the polymerisation of VDF in scCO 2 [25].…”