Copolymers and Hydrogels Based on Vinylphosphonic Acid

Abstract

Polyelectrolyte hydrogels have the advantage of a high swelling ratio and to respond to changes in pH and ionic strength which gives them useful characteristics for biomedical applications. To investigate the possibility to synthesize hydrogels from vinylphosphonic acid (VPA), first the free radical copolymerization of VPA and methyl acrylate (MA) was investigated at temperatures between 60 and 80 °C. Second free radical copolymerization of VPA with ethylene glycol diacrylate (EGDA) at 80 °C was studied to obtain a hydrogel. These copolymerizations were successful. For poly(VPA-co-MA) the solubility behavior, NMR spectra, and titration curves of the resulting products proved the existence of copolymers, and for poly(VPA−EGDA) gels a high mass swelling ratio in water was observed, showing that they behave as hydrogels. At pH values between 3 and 9 the degree of swelling displayed low dependence on pH, but deswelling upon addition of salt was observed. A total conversion between 15 and 79% was obtained for poly(VPA-co-MA) depending on the percentage of VPA in the feed and on the temperature. A higher conversion was achieved when the percentage of VPA in the feed was lower, and the polymerization temperature was higher. A nonideal behavior of the copolymerization in terms of VPA content in the resulting polymers as a function of VPA in the feed was observed. This was attributed to the participation of VPA−anhydride in the copolymerization process as an intermediate giving rise to cyclopolymerization.

Poly(vinyl phosphonic acid): Hydrodynamic Properties and SEC‐Calibration in Aqueous Solution

“…Since the seminal work of B. Bingöl et al has opened the path for synthesis of high molecular weight PVPA and its application as a high-temperature proton conductor in the context of the poly(electrolyte) membrane-fuel cell (PEMFC) a number of publications have appeared dealing with details of the mechanism of the free radical polymerization, [2][3][4][5][6] the mechanism and scope of proton conduction in PVPA, [7][8][9][10][11] and blends [12,13] as well as its potential to form Poly(vinyl phosphonic acid) (PVPA) as obtained by free radical polymerization of aqueous vinyl phosphonic acid was studied by light scattering (SLS, DLS) and size exclusion chromatography (SEC) in dilute aqueous solutions containing sufficient salt in order to screen long range electrostatic interactions. Samples of 37<M w < 110 Â 10 3 were studied.…”

“…hydrogels. [6] The free radical polymerization of VPA is believed to proceed via cyclopolymerization of its anhydride. As a consequence the high molecular weight polymer contains constitutive units coming from head-head and head-tail addition reaction and, therefore, exhibits defects not commonly observed in PAA.…”

Synthesis and characterization of alcogels based on ethylene glycol methyl ether methacrylate-vinyl phosphonic acid copolymers

“…Presence of phosphonic acid functionality in VPA offers interesting properties such as high charge concentration, thermal and oxidative stability in PEMs especially in moderated temperature and anhydrous conditions [19]. VPA has potential in bio applications such as dental cements [20,21] and hydrogels in drug delivery [22][23][24]. Presence COOH and SO 3 H groups in organogel structure improve the alcohol absorbency through ionic interactions and hydrogen bonding.…”

Surface polyion complex gel with poly(vinylphosphonic acid) and poly(N-vinylamide)s

“…5 The copolymerization of VPA with other vinyl monomers is also available to adjust the acidity. 6 In addition, electrostatic interaction with polycation can be used because PVPA is a polyanion. For example, PVPA can form interpolymer complex with poly(vinylpyridine)s 7 and poly(N-methyl-4-piperidinyl methacrylate).…”

“…9 Using divinyl compounds, hydrogels of PVPA have also been prepared. 6,10 PVPA and its esters can be applied mainly as polyanion materials in fuel cells 11 and electronic membranes. 12 However, PVPA should be useful in biomedical applications.…”