Synthesis,photopolymerization, and adhesive properties of new bisphosphonic acid monomers for dental application

Four new monomers, 3‐(N‐methylacrylamido)propylidenebisphosphonic acid, 3‐(N‐propyl‐acrylamido)propylidenebisphosphonic acid, 3‐(N‐hexylacrylamido)propylidenebisphosphonic acid, and 3‐(N‐octylacrylamido)propylidenebisphosphonic acid, have been synthesized in good yields and fully characterized by ¹H, ¹³C, ³¹P NMR, and HRMS. The copolymerization of these monomers with N,N′‐diethyl‐1,3‐bis(acrylamido)propane (DEBAAP) has been investigated with differential scanning calorimetry. These mixtures show a higher reactivity than DEBAAP. New self‐etch dental primers, based on these acrylamide monomers, have been formulated. Dentin shear bond strength measurements have shown that primers based on these bisphosphonic acids assure a strong bond between the tooth substance and a dental composite. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 5258–5271, 2009     

一种两性三元共聚物的合成

选用聚乙二醇二丙烯酸酯(PEGDA)为扩链剂,以丙烯酰胺(AM)、2-甲基-2-丙烯酰胺基丙磺酸(AMPS)、甲基丙烯酰氧乙基三甲基氯化铵(DMC)为主单体,采用水溶液聚合方法合成了两性三元共聚物AM/AMPS/DMC;测定了共聚物的性能,并利用红外光谱研究了其分子结构.结果表明,所合成的共聚物具有良好的耐酸和高温稳定性,以及高抗剪切率.     

Thermodynamics of phase equilibrium for systems containing N-isopropyl acrylamide hydrogels

Hydrogels are crosslinked polymers of hydrophilic monomers. Hydrogels can swell and shrink in aqueous solutions. The swelling behavior of hydrogels and the encountered phase behavior are of interest in many areas, e.g., in biotechnology, membrane science and controlled drug release. This contribution presents the criteria for such phase equilibria and a previously developed thermodynamic model for correlating/predicting the swelling and shrinking of hydrogels. The application of the method is demonstrated by describing the swelling equilibrium of some synthetic, non-ionic N-isopropyl acrylamide (N-IPAAm) hydrogels in aqueous solutions of sodium chloride at 298 K. Furthermore, new experimental results are presented for the degree of swelling of synthetic hydrogels that contain – besides the non-ionic monomer N-IPAAm – either a combination of a cationic comonomer (here, N-[3-(dimethylamino)propyl]methacrylamide (DMAPMA)) and an anionic comonomer (here, 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS)) or a zwitterionic comonomer (here, [3-(methacryloylamino)propyl]dimethyl(3-sulfopropyl)ammonium hydroxide inner salt (MPSA)). These gels were equilibrated with aqueous solutions of sodium chloride at 298 K.     

PHASE BEHAVIOUR IN THE SYSTEM TRS 10-80/BUTANOL/PETROL D/SODIUM CHLORIDE

The phase diagrams for the system TRS 10-80/ butanol/Petrol D/sodium chloride show that the weight ratio B = TRS/butanol is very important for the stability of the microemulsion. R = 1 results in a very limited microemulsion region. Provided the ratio is >1.22 the minimum amount of (TRS+butanol) necessary to form a microemulsion, with equal amounts of water and Petrol D, is 15% and approximately independent of R.However, as R is increased the solubility of water in the (TRS+butanol) mixture is reduced and a liquid crystalline phase is formed. Its presence increases the viscosity and the kinetic stability of the emulsions formed at low content of Petrol D.

Addition of electrolyte reduces the minimum amount of (TRS+butanol) necessary to form a microemulsion. Furthermore, systems rich in water separate into two phases; an upper microemulsion phase and a lower aqueous phase. This can be explained in terms of a redistribution of the butanol from the aqueous phase to the oil phase. It is shown that, although the studied system contains unpurified technical products, the phase behaviour is very similar to that of model systems of pure chemicals.

X-ray diffraction showed that the liquid crystal line phase was lamellar. The thickness of the amphiphilie layer was 26-28 Å. It is more difficult to obtain direct information of the structure of the microemulsion. However, conductivity data indicated a “bicontinuous” structure or at least, the occurrence of highly dynamic aggregates over a large concentration range.     

Polymerization kinetics of phosphonic acids and esters using an iodonium initiator

Phosphonic acids are known to be useful monomers in dental restorative materials because of their good potential to provide enhanced adhesion to hydroxyapatite and their high hydrolytic stability. In this study, the photopolymerization of phosphonic acid‐based monomer via the camphorquinone (CQ)/ethyl‐4‐(dimethylaminobenzoate) (EDAB) photoredox system is compared with a ternary system composed of iodonium hexafluorophosphate and CQ/EDAB. Photocalorimetry shows that the ternary system does not provide a significant acceleration of the polymerization with either acrylamide or methacrylate phosphonic acids. The complexation of the iodonium by the phosphonic moiety of the acidic monomers leads to a lowered iodonium reactivity and reduced polarizability of the medium and as a consequence limits the rate enhancement effect normally observed by phosphonic acids on the polymerization rate. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013 , 51, 5046–5055     

Optimal estimation of reactivity ratios for acrylamide/acrylic acid copolymerization

Reactivity ratios for the important acrylamide (AAm)/acrylic acid (AAc) copolymerization system exhibit considerable scatter in previously published literature, and therefore, there is a need for more definitive values for these reactivity ratios. An appropriate methodology, based on the error‐in‐variables‐model (EVM) framework along with a direct numerical integration procedure, is applied in order to determine reliable reactivity ratios. The reliability of the results is confirmed with extensive and independent replication. Furthermore, via an EVM‐based criterion for the design of experiments using mechanistic models, optimal feed compositions are calculated, and from these optimal reactivity ratios are estimated for the first time (r_AAm = 1.33 and r_AAc = 0.23) based on information from the full conversion range. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013 , 51, 4819–4827     

Effects of TEMED and EDTA on the structural and mechanical properties of NIPAAm/Na+MMT composite hydrogels

N‐isopropyl acrylamide (NIPAAm) hydrogels are known as thermosensitive crosslinked polymer networks. In this work, the network parameters of their composites, i.e., NIPAAm/sodium montmorillonite (NIPAAm/Na⁺MMT) hydrogels synthesized by free radical solution polymerization in the presence of two different types of accelerator (tetramethyl ethylenediamine (TEMED) and ethylenediamine tetraacetic acid (EDTA)) and initiator (potassium persulphate (K₂S₂O₈) and cerium ammonium nitrate ((NH₄)₂Ce(NO₃)₆), Ce(IV)) using five different clay content (in the range of 1.0–5.0 wt % of total monomer concentration) at 25 °C were presented and discussed. FTIR spectra, XRD patterns, SEM photographs, and network parameters of the samples indicated that the presence of COOH groups on EDTA molecules was resulted in the formation of exfoliated structures and the activity of EDTA/KPS redox pair was higher than those of TEMED/KPS and EDTA/Ce (IV) pairs. The compression moduli (G) of the hydrogels initiated with EDTA/Ce(IV) redox pair showed smooth and continual changings with increase in Na⁺MMT content (for swelling equilibrium at 25 °C) on the contrary of EDTA/KPS and TEMED/KPS pairs. It might be related to low initiator efficiency of cerium ammonium nitrate than KPS molecules, having higher effective crosslinking density with increasing clay content. On the other hand, the G moduli of NIPAAm/Na⁺MMT hydrogels (above their phase transition temperature) initiated with TEMED/KPS redox pair were higher than the others because of the more hydrophobic nature of TEMED molecules. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 1256–1264, 2010     

New hydrogels from interpenetrated physical gels of agarose and chemical gels of polyacrylamide: Effect of relative concentration and crosslinking degree on the viscoelastic and thermal properties

In this article, we report on the viscoelastic and thermal properties of agarose–polyacrylamide (PAAm) interpenetrating polymer hydrogels (IPHs) and semi‐IPHs as a function of agarose concentration and PAAm crosslinking degree. The results demonstrated that the agarose is able to gel in the presence of crosslinked and linear IPHs. In addition, the reticulation of PAAm in the presence of agarose is confirmed for the case of IPHs giving rise to systems with dimensional stability at high temperatures. The formation of a fully IPH was ascertained at low agarose concentrations. A study of the morphology and nanoscale elasticity of the different systems has been carried out with atomic force microscopy/ultrasonic force microscopy (UFM). UFM data provide further evidence of interpenetration, allowing us to visualize—if present—phase‐separated domains with nanoscale resolution for the various crosslinking degrees and PAAm and agarose concentrations used during the formation of the IPHs. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2010     

Acrylamide inverse microemulsion polymerization in a paraffinic solvent: Rolling‐M‐245

The inverse microemulsion polymerization of acrylamide in a paraffinic solvent, Rolling‐M‐245, stabilized by a mixture of nonionic surfactants (Emulan‐ELP‐11 and Brij‐92), was studied. Pseudoternary phase diagrams of this system were determined, and a range of hydrophilic‐lipophilic balance (HLB) values, from 8.98 to 9.2, were selected as the most favorable for acrylamide polymerization. The influence of factors such as the initiator composition, HLB, percentage of the aqueous phase, and addition of the monomer by steps on the final conversion and polyacrylamide molar masses were investigated. High conversions and molar masses were generally obtained with the different formulations. The polyacrylamide molar masses were influenced by the HLB and content in the aqueous phase. The addition of the aqueous phase by steps led to a progressive diminution of the molar masses as the number of stages increased. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2495–2503, 2005     

Photoinitiation of acrylamide polymerization using the dianions of rhodizonic and croconic acids

Polymerization of acrylamide has been initiated by the photochemical reactions of the dianions of croconic acid (1,2-dihydroxycyclopentenetrione) and rhodizonic acid (1,2-dihydroxycyclohexenetetrone) in the presence of various acceptor molecules. Photoinitiation was most efficient with croconic acid where a maximum quantum yield for polymerization of 2 x 10³ was observed in neutral solution. Kinetic studies using this initiator showed that the rate of polymerization was a linear function of the concentration of monomer and proportional to the square root of the light absorbed by the croconate dianion. The rate of initiation of radicals calculated from the rate of polymerization was compared with the rate of production of radicals calculated from previous studies of the photochemistry of the croconate dianion and the mechanism of photoinitiation is discussed. © 1992 John Wiley & Sons, Inc.