Spiro Orthocarbonates Research Articles

Influences of iodonium salts on the properties of a hybrid composite resin containing BisS-GMA and expanding monomer modified epoxy

In order to reduce shrinkage and improve the mechanical properties of dental composite resins, we designed a hybrid resin formulation containing a novel matrix resin, BisS-GMA [bisphenol-Sbis( 3-methacrylato-2-hydroxypropyl)ether], and epoxy modified by a spiro-orthocarbonate (SOC) expanding monomer. Then, we tested the effects of an iodonium salt, diphenyliodonium hexafluorphosphate (DPIHFP), on the properties of the hybrid resin with seven different concentrations. The hybrid resin was polymerized by a ternary photo-initiator system. The volumetric shrinkage (VS), degree of conversion (DC) and compressive strength (CS) were assessed using AcuVol™, FTIR and a universal testing machine, respectively. The VS, DC and CS were improved with increasing DPIHFP concentration, but a high concentration of DPIHFP had a negative influence on the mechanical properties of the hybrid resin and offered no added improvement in the VS and DC. The best performance of a composite resin containing BisS-GMA and SOC-modified epoxy was achieved with 2wt% DPIHFP. The results also indicated that the resin containing BisS-GMA was superior to that containing Bis-GMA in terms of VS, DC and CS.

Synthesis of Copolymers Containing Double Spiro Orthocarbonate and Used as Anti-shrinkage Additives in Epoxy Resin Composite

A novel copolymer containing a double spiro orthocarbonate structure, poly 3-methylene-9-methyleneoxy-3,9-Bis(hydroxymethyl)-1,5,7,11-tetraoxaspiro[5.5] undecane (SOC), was synthesized. The structure of SOC was confirmed by 1H, 13C NMR and FTIR spectra. Prepolymer (SOCP) reacting from SOC and 2,4-toluene diisocynate (TDI) was prepared and used as anti-shrinkage additives in the cationic polymerization of epoxy resin (EP-51). The volume changes of the cured epoxy resin containing SOCP were investigated by density measurements with an electronic hydrometer. The mechanical properties of the modified epoxy resin were investigated by adhesive strength, impact strength and flexural strength, while thermal properties were investigated by thermal gravimetric analysis (TGA).

双環状ビス-γ-ラクトンと, エポキシ基を持つスピロオルトカーボナートとのアニオン交互共重合, および得られるポリマーのカチオン架橋

双環状ビス-γ-ラクトンと, エポキシ基を持つスピロオルトカーボナートとのアニオン交互共重合, および得られるポリマーのカチオン架橋

The effect of hydroxyspiro-orthocarbonates on the cationic photopolymerization of an epoxy resin and on the mechanical properties of the final polymer

It is well known that bicyclic compounds like spiro-orthocarbonates (SOCs) have the ability to reduce or eliminate the shrinkage produced during polymerization. In the work reported, four different SOCs were prepared, two of them with one and two hydroxyl groups, respectively, another with two alkoxy groups and one reference compound without substituents. It was found that the SOCs with hydroxyl groups increased the photopolymerization rate and conversion of an epoxycycloaliphatic monomer, while the compound with butoxy groups had an antagonistic effect, reducing both photopolymerization rate and conversion, due to the basic character of the ether groups. The reference compound did not display accelerating effects but it did increase slightly the conversion. Dynamic mechanical analysis revealed that the SOC with two hydroxyl groups increased the values of storage modulus of the obtained polymer in comparison with the polymer from pristine monomer. This may be due to the multifunctionality of this compound that induced a higher level of crosslinking, while the SOC with one hydroxyl group had the opposite effect, decreasing the viscoelastic property values of the polymer due to chain-transfer reactions originated by the hydroxyl groups. The SOC with two hydroxyl groups was the more efficient of the studied compounds in reducing the shrinkage of the cured polyether. Copyright © 2011 Society of Chemical Industry

Shrinkage properties of a modified dental resin composites containing a novel spiro-orthocarbonate expanding monomer

Objectives This study investigated the photopolymerization-induced shrinkage properties of conventional methacrylate-based composites modified by a novel spiro-orthocarbonate (SOC) expanding monomer. Methods The epoxy monomer and SOC expanding monomer were added to a methacrylate-based resin matrix at five different ratios ranging from 20 wt.% (SOC + Epoxy) (group 1) to 60 wt.% (SOC + Epoxy) (group 5). Volumetric shrinkage and contraction stress developing after polymerization were measured using X-ray micro-computed tomography and a universal testing machine, respectively. Results The volumetric shrinkage of the resin composite samples ranged from 0.92% (group 5) to 3.85% (control group) 30 min after light curing. Group 5 had the lowest volumetric shrinkage ( p < 0.05), followed by groups 4, 3, 2 and 1. The contraction stress of the materials ranged from 1.86 MPa (group 5) to 3.56 MPa (control group). The lowest contraction stress was also observed in group 5, 30 min after curing ( p < 0.05). Conclusion Including SOC expanding monomer reduced volumetric shrinkage and contraction stress of composites in comparison with conventional methacrylate-based composites.

Characteristics of dental restorative composites fabricated from Bis-GMA alternatives and spiro orthocarbonates

The characteristics of resin matrices containing 2,2-bis[4-(2-hydroxy-3-methacryloyloxy propoxy) phenyl] propane (Bis-GMA) alternatives and spiro orthocarbonate (SOC) were examined to produce dental restorative composites exhibiting lower curing shrinkage and better mechanical strength than the commercially available dental composites. Bis-GMA alternatives were prepared by replacing the hydroxyl groups in Bis-GMA with alkoxy groups. Various SOCs that showed the expected volume expansion during the curing reaction caused by the ring opening reaction were added to Bis-GMA alternatives for a further decrease in curing shrinkage. The curing shrinkage of the dental composites containing Bis-GMA alternative and SOC was always lower than that of the dental composite used as the control, which contained 70 wt% Bis-GMA and 30 wt% triethylene glycol dimethacrylate (TEGDMA) as the resin matrix. Furthermore, the mechanical strength of the dental composites prepared from the 2,2-bis[4-(2-methoxy-3-methacryloyloxy propoxy)phenyl]propane (Bis-M-GMA) mixture containing approximately 10 wt% SOC was higher than that of the dental composite used as the control.

Synthesis of a novel spiro orthocarbonate containing bisphenol-a unit and its application to the dental composites

Dental restorative composites containing spiro orthocarbonates (SOCs) have been studied extensively to minimize the volumetric shrinkage that occurs during polymerization. Previous reports suggested that dental composites with low volumetric shrinkage could be obtained by mixing SOC with conventional resins. However, its inclusion had adverse effects on the mechanical properties of dental composites. A novel SOC (2,2-bis-4,4′-(7-phenyl-1,4,6,9-tetraoxaspiro[4.4]nona-2-ylmethoxyphenyl)propane), SOC-N, was synthesized to overcome these adverse effects resulting from the previously developed SOCs. The mechanical strength and volumetric shrinkage of the dental composites composed of 70 wt% inorganic fillers and resin matrices containing SOC-N, 2,2-bis-[4-(2-hydroxy-3-methacryloyloxy propoxy) phenyl] propane (Bis-GMA), and triethylene glycol dimethacrylate (TEGDMA) were explored. When compared to a control resin-containing composite (Bis-GMA/TEGDMA=70/30), the volumetric shrinkage of the composite containing new resin matrix, obtained through the addition of SOC-N to the Bis-GMA/TEGDMA=70/30 mixture, was reduced gradually by increasing the SOC-N content. Furthermore, the latter sample showed better mechanical strength than the former when the resin matrix contained 30 wt% SOC-N.

Novel diol spiro orthocarbonates derived from glycerol as anti‐shrinkage additives for the cationic photopolymerization of epoxy monomers

AbstractShrinkage that takes place during polymerizations induces internal stress in polymeric materials generating a series of problems like poor adhesion to substrates and delamination in coatings or microcracks and microvoids in composites. Some additives like spiro orthocarbonates can reduce or eliminate this shrinkage. This paper deals with the synthesis of novel diol spiro orthocarbonates (DIOL SOCs) and their effect as anti‐shrinkage additives in the photopolymerization of the monomer 3,4‐epoxycyclohexyl‐3′, 4′‐epoxycyclohexanecarboxylate. It was found that increasing the concentration of the DIOL SOCs resulted in higher conversion of the monomer due to the presence of hydroxyl groups. The viscoelastic properties of the polymer products were also measured. It was observed that at 5 mol% of the mixture of DIOL SOCs there was an increase in the storage modulus due to the crosslinking produced by the bifunctional SOCs. However, at higher concentrations, a decrease in the storage modulus was observed. The level of shrinkage using the DIOL SOCs at 20 mol% was reduced by 45% when compared to the case without any additive. DIOL SOCs can be easily prepared by reacting glycerol with tetraethylorthocarbonate. These additives reduced significantly the level of shrinkage of the polyether derived from the diepoxycyclohexane monomer. Copyright © 2010 Society of Chemical Industry

Iodine-Catalyzed Synthesis of Spiroorthcarbonates under Neutral Conditions

Scheme 2 Spiroorthocarbonates (SOCs) are one of the most important categories of monomers which polymerize without any shrinkage in volume. They are specially useful in the synthesis of materials such as precision materials, adhesives, and dental composites. There are few methods for the synthesis of SOCs. Sakai et. al. reported a novel synthesis of SOCs from the reaction of organotin compounds with carbon disulfide. This method is not recommended, Since it involves many steps and highly toxic unstable organotin compounds. Endo and Okawara also reported another synthetic method by treatment of tetraalkylorthocarbonate with various diols in the presence of TsOH as an acidic catalyst. The main disadvantage of this method comes from inevitable formation of symmetrical SOCs during the preparation of unsymmetrical analogs. Synthesis of SOCs is also achieved by using highly toxic thiophosgene which is not advised. The one pot treatment of dichlorodiphenoxymethane and various diols is useful only for the synthesis of symmetrical SOCs. Endo used dichlorodiphenoxymethane in the presence of p-toluenesulfonic acid monohydrate for the preparation of asymmetric SOCs. The long reaction times and relatively low yields are the disadvantages of this method. Therefore; an alternative method that can overcome these drawbacks and can be applied to the synthesis of symmetrical and unsymmetrical SOCs is desirable. Recently, molecular iodine has been the focus of attention in organic transformations as a mild, readily available and neutral Lewis acid. In continuation of our previous research on spiroorthocarbonates, in this paper, we wish to report on the use of this catalyst for the synthesis of symmetrical and unsymmetrical SOCs from 2,2-diphenoxy-1,3-dioxane and 1,3-diol under neutral conditions. 2,2-Diphenoxy-1,3-dioxanes (1a-b) used in this work were prepared according to literature. The reaction of 2,2-diphenoxy-1,3-dioxane (1a) with 1,3propanediol as a model reaction was performed in different aprotic solvents in the presence of I2. On the basis of the reaction times and yields, CH2Cl2 was selected as a most suitable solvent for the synthesis of SOCs. On the other hand, in order to get an insight into the optimum molar ratio of the catalyst, the model experiment was studied in four different molar ratios of the I2, and the results clearly demonstrate that 0.5% molar ratio of I2 related to 2,2-diphenoxy-1,3-dioxane is the optimal ratio. (Table 1) 2,2-Diphenoxy-1,3-dioxanes (1a-b) were reacted with various diols under neutral conditions in the presence of catalytic amount of molecular iodine (0.5 mol%) in CH2Cl2 to yield the corresponding SOCs (2a-j). (Scheme 1) The efficiency and validity of this method for the synthesis of SOCs (2a-j) can be deduced from the data in Table 2. Moreover, the prolongation of the reaction has no effect on the product distribution unlike the previous published method which uses protic acid catalyst. The proposed mechanism of the synthesis of SOCs catalyzed by molecular iodine for a typical synthesis (Entry 1) is presented in Scheme 2. In conclusion, we have developed a new modified, efficient and chemoselective method for the synthesis of symmetrical and unsymmetrical SOCs catalyzed by molecular iodine with good to high yields.

Synthesis of an epoxy functionalized spiroorthocarbonate used as low shrinkage additive in cationic UV curing of an epoxy resin

The synthesis of an epoxy functionalized spiroorthocarbonate (SOC) is reported. The obtained monomer has been used a slow shrinkable additive in cationic UV curing of a commercially available dicycloepoxy resin. A polymer network flexibilization was evidenced by increasing the SOC content in the photocurable formulation. It has been demonstrated that SOC acts as shrinkage reduction additive reaching expansion on volume after polymerization in the presence of 10 wt% of the functionalized spiroorthocarbonate.

Synthesis of copolymers containing a spiro orthocarbonate moiety and evaluation of the volume change during their cationic crosslinking

AbstractSpiro orthocarbonate (SOC) monomers having either an exomethylene group {3,3‐dimethyl‐9‐methylene‐1,5,7,11‐tetraoxaspiro[5.5]undecane (ExoSOC)} or an allyl group {9‐allyl‐3,3‐dimethyl‐1,5,7,11‐tetraoxaspiro[5.5]undecane (AllylSOC)} were radically copolymerized with vinyl monomers at several feed ratios to obtain the corresponding copolymers having SOC moieties in the side chain. The obtained copolymers were crosslinked via the double ring‐opening polymerization of the SOC moieties by a treatment with boron trifluoride etherate. The volume changes during the crosslinking of the copolymers were evaluated by density measurements with a gas pycnometer. As the SOC moiety composition increased, the volume shrinkage during the crosslinking was suppressed, and that finally changed into volume expansion. The volume changes during the crosslinking of the copolymers from AllylSOC were slightly larger than those of the copolymers from ExoSOC. The higher volume expansions in the crosslinking of AllylSOC‐based copolymers were ascribable to the lower steric hindrance around the SOC moieties. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 7040–7053, 2006

Structural and phenomenological study on the cationic curing of mixtures of epoxy resin and 5,5‐dimethyl‐1,3‐dioxane‐2‐one

AbstractYtterbium and lanthanum triflates were used as initiators to cure a mixture of diglycidylether of bisphenol A (DGEBA) and 5,5‐dimethyl‐1,3‐dioxane‐2‐one (DMTMC). The evolution of the curing was studied by differential scanning calorimetry (DSC) and Fourier transform infrared in the attenuated‐total‐reflection mode (FTIR/ATR). FTIR/ATR was used to monitor the competitive reactive processes and to quantify the evolution of the groups involved in the curing process. We observed the formation of a five‐membered cyclic carbonate, which remains unreacted at the chain ends because of an equilibrium process between the spiroortho carbonates that had formed as intermediate species and also the loss of CO2, which was quantified by thermogravimetry. The kinetics were studied by DSC and analyzed by isoconversional procedures. Thermogravimetric analysis (TGA) and dynamic mechanical thermal analysis (DMTA) experiments were used to evaluate the properties of the thermosets obtained. The phenomenological changes that take place during curing were studied and represented in a time‐temperature‐transformation (TTT) diagram. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 4546–4558, 2006

Dental restorative composites containing 2,2‐bis‐[4‐(2‐hydroxy‐3‐methacryloyloxy propoxy) phenyl] propane derivatives and spiro orthocarbonates

Various dental restorative composite resins containing 2,2-bis-[4-(2-hydroxy-3-methacryloyloxy propoxy) phenyl] propane (Bis-GMA) derivatives and spiro orthocarbonates (SOCs) were explored for minimizing the volumetric shrinkage that generally occurs during polymerization. Previous reports suggested mixing Bis-GMA with its derivative TMBis-GMA (2,2-bis[3,5-dimethyl-4-(2-hydroxy-3-methacryloyloxy propoxy) phenyl] propane) to obtain a dental composite with low volumetric shrinkage. It was hypothesized that spiro orthocarbonates would expand volumetrically during polymerization, because of their sophisticated ring-opening reactions; therefore several of them were added to the mixture of Bis-GMA and TMBis-GMA to bring about further reductions in volumetric shrinkage. It was indeed possible to reduce the extent of volumetric shrinkage of dental composites containing SOCs, and to do so without compromising these resins' mechanical properties.

Preparation of Asymmetric Spiro Orthocarbonates via Cyclic Thionocarbonates.

The development of monomers that show no shrinkage in volume upon polymerization is highly desirable in the field of materials such as dental fillings, high-strength composites, precision castings, and adhesives. 1 Volume shrinkage during polymerization results from the conversion of van der Waals distances between monomers to covalent bond lengths. Since the van der Waals distance separates monomer molecules approximately three times greater than a covalent bond does, the formation of new covalent bonds upon polymerization is destined to produce the substantial amount of volume contraction. A hopeful approach to prevent this shrinkage could be attained by using monomers that polymerize via the double ring-opening process, which results in two bonds breaking for each new bond formation. Since the double ring-opening polymerization was reported in 1972, 2 various monomers based on spiro orthoester (SOE), 3 bicyclo orthoester (BOE), 4 polycyclic ketal lactone (PKL), 5 cyclic ether, 6 spiroketal, 7 and spiro orthocarbonate (SOC) skeletons 8 have been developed to show the expansion in volume upon polymerization. Among them, spiro orthocarbonates (SOCs) are the most widely investigated monomers because they show the biggest volume expansion. Moreover SOCs containing exo-methylene groups undergo the ring-opening polymerization not only with cationic initiators 9 but also with radical initiators. 10 Asymmetric SOCs possessing one exo-methylene group are more favorable than symmetric SOCs, because the extra exomethylene group remained in the polymer from symmetric monomers affords the crosslinking reaction that causes the volume shrinkage. 11 Recently, N,S- 12 and S,S-analogs 13 of

Preparation of Asymmetric Spiro Orthocarbonates via Cyclic Thionocarbonates

The development of monomers that show no shrinkage in volume upon polymerization is highly desirable in the field of materials such as dental fillings, high-strength composites, precision castings, and adhesives. 1 Volume shrinkage during polymerization results from the conversion of van der Waals distances between monomers to covalent bond lengths. Since the van der Waals distance separates monomer molecules approximately three times greater than a covalent bond does, the formation of new covalent bonds upon polymerization is destined to produce the substantial amount of volume contraction. A hopeful approach to prevent this shrinkage could be attained by using monomers that polymerize via the double ring-opening process, which results in two bonds breaking for each new bond formation. Since the double ring-opening polymerization was reported in 1972, 2 various monomers based on spiro orthoester (SOE), 3 bicyclo orthoester (BOE), 4 polycyclic ketal lactone (PKL), 5 cyclic ether, 6 spiroketal, 7 and spiro orthocarbonate (SOC) skeletons 8 have been developed to show the expansion in volume upon polymerization. Among them, spiro orthocarbonates (SOCs) are the most widely investigated monomers because they show the biggest volume expansion. Moreover SOCs containing exo-methylene groups undergo the ring-opening polymerization not only with cationic initiators 9 but also with radical initiators. 10 Asymmetric SOCs possessing one exo-methylene group are more favorable than symmetric SOCs, because the extra exomethylene group remained in the polymer from symmetric monomers affords the crosslinking reaction that causes the volume shrinkage. 11 Recently, N,S- 12 and S,S-analogs 13 of

A Novel Synthetic Approach to Networked Polymers without Volume Shrinkage on Cross-Linking Polymerization: Cationic Copolymerization of a Monofunctional Epoxide and a Spiro Orthocarbonate Bearing Norbornene Backbone

A Novel Synthetic Approach to Networked Polymers without Volume Shrinkage on Cross-Linking Polymerization: Cationic Copolymerization of a Monofunctional Epoxide and a Spiro Orthocarbonate Bearing Norbornene Backbone

Copolymerization behavior and kinetics of an epoxy copolymer with zero shrinkage

AbstractThe copolymerization behavior and the apparent cure kinetics of epoxy resin E51 containing the expanding monomer 3,9‐di(5‐norbornene‐2,2)‐1,5,7,11‐tetraoxaspiro [5,5] undecane (NSOC, norbornene spiro orthocarbonate), were investigated by using differential scanning calorimetry (DSC), Fourier transform infrared (FTIR) spectroscopy, and nuclear magnetic resonance (NMR) spectroscopy. Evidence for random copolymerization of the E51‐NSOC system was obtained by dynamic mechanical analysis and electron microscopy. The ring‐opening reaction of the epoxy resin was found to be first order with an activation energy of 62.0 kJ/mol and the reaction with the expanding monomer NSOC was second order with an activation energy of 121.3 kJ/mol. The comonomers were joined with an ether linkage. Longer copolymerization sequence lengths were obtained with higher NSOC contents in the copolymer. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1457–1464, 2002; DOI 10.1002/app.10485

A semiempirical quantum mechanical study of the cationic homopolymerization of expanding and potentially expanding monomer systems

The cationic homopolymerization reactions of expanding and potentially expanding monomer systems were modeled and the energies of activation were calculated using the AM1 semiempirical quantum mechanical method. The results were used to determine the relative reactivity of study monomers with respect to spiro-orthocarbonates (SOC) and epoxides. All expanding monomers studied were endothermic by 4–16kcal/mol except the methylated bicyclic orthoesters which had an enthalpy of reaction of essentially 0kcal/mol. Three potentially expanding monomers were exothermic by 3–18kcal/mol. The energies of activation for all expanding monomers ranged from 28–37kcal/mol. The energies of activation for SOCs and epoxides are approximately 32 and 0–3kcal/mol, respectively [1,2]

AM1 semiempirical computational analysis of the homopolymerization of spiroorthocarbonate

Spiroorthocarbonates (SOCs) are monomers that have been shown to expand when homopolymerized. SOCs are potential monomer systems that can be combined with other monomers such as epoxy resin to produce a non-shrinking dental matrix for dental composites. The purpose of this study was to use a computer model (AM1) to study possible homopolymerization pathways for several SOC monomers. The gas phase transition states of three feasible reaction mechanisms for the homopolymerization of four spiroorthocarbonate 1,5,7,11-tetraoxaspiro[5,5]undecane (TOSU) systems have been examined using the AM1 semiempirical quantum mechanical model. In addition to the base TOSU noted above, the 2,8-dimethyl, 2,4,8,10-tetramethyl, and the 3,3,9,9-tetramethyl analogs were used in this study. The results of these calculations produced the heats of reaction, activation enthalpies and transition state structures. Our calculations indicate stabilization of the transition states by electron-donating and resonance-stabilizing substituent groups. The energies of activation of all of these systems were between 24 and 38 kcal/mol and all reactions were endothermic. Further, we found that there was a significant intermolecular attraction between TOSU monomers (≈3.5 kcal/mol). When compared with experimental studies of methylated TOSU by Sakai and co-workers, our calculations agree with the preferred site of nucleophilic attack, but not with the experimental rate results. It was concluded that the homopolymerization of the unsubstituted TOSU and its derivatives studied was endothermic and that the rate of homopolymerization of TOSU depends on an intermolecular pre-association of TOSU monomer in the condensed phase.

Synthesis, cationic polymerization and curing reaction with epoxy resin of 3,9-di(p-methoxybenzyl)-1,5,7,11-tetra-oxaspiro(5,5)undecane

A new spiro ortho carbonate, 3,9-di(p-methoxybenzyl)-1,5,7,11-tetra-oxaspiro(5,5)undecane was prepared by the reaction of 2-methoxybenzyl-1,3-propanediol with di(n-butyl)tin oxide, following with carbon disulfide. Its cationic polymerization was carried out in dichloromethane using BF3-OEt2 as catalyst. The [1H], [13C]NMR and IR data as well as elementary analysis of the polymers obtained indicated that it underwent double ring-opening polymerization. The polymerization mechanism is discussed. The curing reaction of bisphenol A type epoxy resin in the presence of the monomer and a curing agent was investigated. DSC measurements were used to follow the curing process. In the case of boron trifluoride-o-phenylenediamine (BF3-OPDA) as curing agent, two peaks were found on the DSC curves, one of which was attributed to the polymerization of the epoxy group, and the other to the copolymerization of the monomer with the isolated epoxy groups or homopolymerization. However, when BF3-H2NEt was used as curing agent, only one peak was present. IR measurement of the modified epoxy resin with various weight ratios of epoxy resin/monomer was performed in the presence of BF3-H2NEt as curing agent. The results demonstrate that the conversion of epoxy group increases as the content of monomer increases. The curing process and the structure of the epoxy resin network are discussed. © 2000 Society of Chemical Industry