Urethane Dimethacrylate Monomer Research Articles

Chemical Modification of Dental Dimethacrylate Copolymer with Tetramethylxylylene Diisocyanate-Based Quaternary Ammonium Urethane-Dimethacrylates-Physicochemical, Mechanical, and Antibacterial Properties.

In this study, two novel quaternary ammonium urethane-dimethacrylates (QAUDMAs) were designed for potential use as comonomers in antibacterial dental composite restorative materials. QAUDMAs were synthesized via the reaction of 1,3-bis(1-isocyanato-1-methylethyl)benzene with 2-(methacryloyloxy)ethyl-2-decylhydroxyethylmethylammonium bromide (QA10+TMXDI) and 2-(methacryloyloxy)ethyl-2-dodecylhydroxyethylmethylammonium bromide (QA12+TMXDI). Their compositions with common dental dimethacrylates comprising QAUDMA 20 wt.%, urethane-dimethacrylate monomer (UDMA) 20 wt.%, bisphenol A glycerolate dimethacrylate (Bis-GMA) 40 wt.%, and triethylene glycol dimethacrylate (TEGDMA) 20 wt.%, were photocured. The achieved copolymers were characterized for their physicochemical and mechanical properties, including their degree of conversion (DC), glass transition temperature (Tg), polymerization shrinkage (S), water contact angle (WCA), flexural modulus (E), flexural strength (FS), hardness (HB), water sorption (WS), and water leachability (WL). The antibacterial activity of the copolymers was characterized by the minimum bactericidal concentration (MBC) and minimum inhibitory concentration (MIC) against Staphylococcus aureus and Escherichia coli. The achieved results were compared to the properties of a typical dental copolymer comprising UDMA 40 wt.%, Bis-GMA 40 wt.%, and TEGDMA 20 wt.%. The introduction of QAUDMAs did not deteriorate physicochemical and mechanical properties. The WS and WL increased; however, they were still satisfactory. The copolymer comprising QA10+TMXDI showed a higher antibacterial effect than that comprising QA12+TMXDI and that of the reference copolymer.

Degree of conversion and physicomechanical properties of newly developed flowable composite derived from rice husk using urethane dimethacrylate monomer.

This study evaluated the use of urethane dimethacrylate (UDMA) as a base monomer to prepare the newly developed flowable composite (FC) using nanohybrid silica derived from rice husk in comparison to bisphenol A-glycidyl methacrylate (Bis-GMA) on the degree of conversion and physicomechanical properties. The different loadings of base monomer to diluent monomer were used at the ratio of 40:60, 50:50, and 60:40. The bonding analysis confirmed the presence of nanohybrid silica in the newly developed FC. Independent t-test revealed a statistically significant increase in the degree of conversion, depth of cure and Vickers hardness of the UDMA-based FC, while surface roughness showed comparable results between the two base monomers. In conclusion, UDMA-based FC demonstrated superior performance with 60%-65% conversions, a significantly higher depth of cure exceeding 1 mm which complies with the Internal Standard of Organization 4049 (ISO 4049), and a substantial increase in Vickers hardness numbers compared to Bis-GMA-based FC, making UDMA a suitable alternative to Bis-GMA as a base monomer in the formulation of this newly developed FC derived from rice husk.

Novel mechanically strong and antibacterial dimethacrylate copolymers based on quaternary ammonium urethane-dimethacrylate analogues.

This study assumed that the quaternary ammonium urethane-dimethacrylate derivative (QAUDMA-m, where m was 8, 10, 12, 14, 16, 18, and corresponded to the number of carbon atoms in the N-alkyl substituent) can be used to achieve copolymers with high mechanical performance and antibacterial activity. Photocured copolymers of bisphenol A glycerolate dimethacrylate (Bis-GMA) 40wt%, QAUDMA-m 40wt%, and triethylene glycol dimethacrylate (TEGDMA) 20wt% (BG:QAm:TEG) were characterized by the degree of conversion (DC), flexural strength (FS), flexural modulus (E), hardness (HB), and antibacterial properties (the number of bacteria colonies adhered to copolymer surfaces and inhibition zone diameter (IZD)) against Staphylococcus aureus and Escherichia coli. Reference copolymers of Bis-GMA, urethane-dimethacrylate monomer (UDMA), and TEGDMA (BG:TEG and BG:UD:TEG) were also characterized. The DC of BG:QAm:TEGs ranged from 0.59 to 0.68, HB from 83.84 to 153.91MPa, FS from 50.81 to 74.47MPa, and E from 1986.74 to 3716.68MPa. The number of S. aureus and E. coli bacteria adhered to BG:QAm:TEG surfaces was from 0 (no bacteria observed) to 6.47 and 4.99log(CFU/mL), respectively. IZD was from 10 and 5mm (no inhibition zone) to 23 and 21mm, respectively. Three copolymers: BG:QA8:TEG, BG:QA10:TEG, and BG:QA12:TEG had similar or better mechanical properties than the reference copolymers, but unlike them, they showed high antibacterial activity against both bacteria strains. The obtained copolymers can offer a good, mechanically efficient, bioactive alternative to BG:TEG and BG:UD:TEG copolymers. The use of such materials can help to make progress in dental health care.

The Influence of Low-Molecular-Weight Monomers (TEGDMA, HDDMA, HEMA) on the Properties of Selected Matrices and Composites Based on Bis-GMA and UDMA.

Bisphenol A-glycidyl methacrylate (bis-GMA) and urethane dimethacrylate (UDMA) are usually combined with low-viscosity monomers to obtain more desirable viscosity, handling characteristics and general properties. The present study determined the flexural strength (FS), flexural modulus (FM), diametral tensile strength (DTS), and hardness (HV) of five matrices and composites based on these resins. The polymerization shrinkage stress (PSS) was also studied for the composites. The polymer matrices were formed using bis-GMA and UDMA. TEGDMA, HEMA and HDDMA acted as co-monomers. The composites had 45 wt.% of filler content. The highest FS and FM were obtained from the UDMA/bis-GMA/TEGDMA/HEMA matrix and the composite (matrix + filler). The best DTS values were obtained from the UDMA/bis-GMA/HEMA matrix and the composite. One of the lowest values of FS, FM, and DTS was obtained from the UDMA/bis-GMA/HDDMA matrix and the composite. All the composites demonstrated similar hardness values. The lowest polymerization shrinkage stress was observed for the UDMA/bis-GMA/TEGDMA/HEMA composite, and the highest PSS was observed for the UDMA/bis-GMA/TEGDMA/HDDMA composite. The addition of HEMA had a positive effect on the properties of the tested materials, which may be related to the improved mobility of the bis-GMA and UDMA monomers.

Effect of Adhesive Resin as a Modeling Liquid on Elution of Resin Composite Restorations.

Background Adhesive resin is increasingly used as a modeling liquid for composite. Based on previous studies, elution of some components from the composite mass negatively affects the oral tissues. Since few studies have focused on the effect of adhesive resin on composite mass, this study aimed to investigate the effect of dental adhesion factors as modeling liquid on the elution of substances from composite restorations. Materials and Methods Sixty-four composite specimens (6 × 2 mm diameter × height) were prepared in four groups (n = 16) by using a Teflon ring. Composite mass was incrementally applied in four layers (0.5 mm). The control group contained no material between the layers, but other groups had one of the single bond, SE bond, and wetting resin adhesives between the layers. Specimens were immersed in distilled water and methanol. The amount of released triethylene glycol dimethacrylate (TEGDMA), urethane dimethacrylate (UDMA), and camphorquinone (CQ) was monitored by gas chromatography after 24 hours and 7 days. Data were analyzed with SPSS software through Kruskal–Wallis and Mann–Whitney U tests (α = 0.05). Results The highest rate of released TEGDMA comonomer was seen in the wetting resin group in the water medium. The highest rate of released UDMA monomer was seen in SE bond and wetting resin groups in the methanol medium after 24 hours. The highest amount of released CQ in the methanol medium was observed in the SE bond group after 7 days. Conclusion Single bond adhesive can be used as modeling liquid since it has no significant effect on the elution of components from composite mass. Whereas, wetting resin and SE bond adhesives are not suitable to be used as modeling liquid due to the high amounts of released TEGDMA and UDMA.

Synthesis and Characterization of Novel Quaternary Ammonium Urethane-Dimethacrylate Monomers-A Pilot Study.

Six novel urethane-dimethacrylate analogues (QAUDMAs) were synthesized and characterized. They consisted of the 2,4,4,-trimethylhexamethylene diisocyanate (TMDI) core and two methacrylate-terminated wings containing quaternary ammonium groups substituted with alkyl chains of 8, 10, 12, 14, 16, or 18 carbon atoms. QAUDMAs, due to the presence of quaternary ammonium groups, may have possible antibacterial effects. Since they showed satisfactory physicochemical properties, they will be subjected to further research towards the development of dental composites with a capacity to reduce secondary caries. The synthesis of QAUDMAs included three stages: (i) transesterification of methyl methacrylate (MMA) with N-methyldiethanolamine (MDEA), (ii) N-alkylation of the tertiary amino group with alkyl bromide, and (iii) addition of TMDI to the intermediate achieved in the second stage. The formation of QAUDMAs was confirmed by 1H and 13C NMR. They were characterized for density (dm), viscosity (η), refractive index (RI), glass transition temperature (Tg), polymerization shrinkage (S), and degree of conversion (DC). QAUDMAs were yellow, viscous resins (the η values ranged from 1.28 × 103 to 1.39 × 104 Pa·s, at 50 °C). Their RI ranged from 1.50 to 1.52, Tg from −31 to −15 °C, DC from 53 to 78%, and S from 1.24 to 2.99%, which is appropriate for dental applications.

An Evaluation of the Properties of Urethane Dimethacrylate-Based Dental Resins.

Most of the dental materials available on the market are still based on traditional monomers such as bisphenol A-glycidyl methacrylate (Bis-GMA), urethane dimethacrylate (UDMA), triethyleneglycol dimethacrylate (TEGDMA), and ethoxylated bisphenol-A dimethacrylate (Bis-EMA). The interactions that arise in the monomer mixture and the characteristics of the resulting polymer network are the most important factors, which define the final properties of dental materials. The use of three different monomers in proper proportions may create a strong polymer matrix. In this paper, fourteen resin materials, based on urethane dimethacrylate with different co-monomers such as Bis-GMA or Bis-EMA, were evaluated. TEGDMA was used as the diluting monomer. The flexural strength (FS), diametral tensile strength (DTS), and hardness (HV) were determined. The impacts of material composition on the water absorption and dissolution were evaluated as well. The highest FS was 89.5 MPa, while the lowest was 69.7 MPa. The median DTS for the tested materials was found to range from 20 to 30 MPa. The hardness of the tested materials ranged from 14 to 16 HV. UDMA/TEGDMA matrices were characterized by the highest adsorption values. The overall results indicated that changes in the materials’ properties are not strictly proportional to the material’s compositional changes. The matrices showed good properties when the composite contained an equal mixture of Bis-GMA/Bis-EMA and UDMA or the content of the UDMA monomer was higher.

A deep investigation into the thermal degradation of urethane dimethacrylate polymer

This work investigates in depth the thermal degradation process of a polymer of urethane dimethacrylate (UDMA). UDMA monomer has been widely used in dental restorations and biomaterials. The use of density functional theory (DFT) calculations provided the bases for understanding the structure and reactivity of the UDMA monomer. Simultaneous thermogravimetry–differential thermal analysis, Photovisual Differential Scanning Calorimetry, and mid-infrared spectroscopy (MIR) were used to examine the depolymerization and degradation process. Non-isothermal kinetics made it possible to determine the best fit (n-dimensional nucleation according to Avrami–Erofeev followed by two competitive processes: nth order with autocatalysis by-product and reaction of nth order). Furthermore, the UDMA-P lifetime (5%) was calculated to show a degradation time of 3 years at 100.0 °C. Notwithstanding, techniques such as MIR and nuclear magnetic resonance 13C, 1H linked to DFT calculations helped to elucidate the cleavage positions and possible degradation by-products of UDMA degradation.

Effect of metal oxide fillers in urethane dimethacrylate polymer with glycerol obtained by photopolymerization synthesis

Urethane dimethacrylate (UDMA) is a monomer widely used in photopolymerization reactions to produce biomaterials, due to its advantageous properties such as mechanical resistance and relatively low viscosity. However, this monomer is expensive. Reducing the quantity of UDMA monomer required to obtain the final polymer, without losing its main properties, is essential not just in terms of costs but also green chemistry principles. It has been demonstrated that glycerol inclusion into the polymeric matrix during polymerization is one way to achieve this goal. Thus, this work proposes the insertion of glycerol and metal oxide fillers (Al2O3, TiO2, Nb2O5, La2O3 and ZrO2) in the photopolymerization of urethane dimethacrylate, with the aim to study how these effects the degree of conversion, as well as the thermal properties of the final polymer. The thermal properties were evaluated using simultaneous thermogravimetry–differential thermal analysis (TG–DTA) and differential scanning calorimetry (DSC). The degree of conversion/rate of polymerization was calculated using mid-infrared spectroscopy (MIR). The polymers filled with Al2O3, TiO2, Nb2O5 and La2O3 exhibited good conversion values of 87.42, 78.47, 77.64 and 75.51%, respectively. For all polymers synthesized, no significant changes were observed in their thermal stability. Lastly, it is suggested that the incorporation of the oxides in the monomeric mixture correlate to the degree of conversion, with scanning electronic microscopy (SEM) analysis suggesting oxide dispersion interferes with the morphology of the polymer.

Validation of a Simple HPLC-UV Method for the Determination of Monomers Released from Dental Resin Composites in Artificial Saliva.

Bisphenol-A (BPA), bisphenol A glycerolate dimethacrylate (Bis-GMA), triethylene glycol dimethacrylate (TEGDMA), and urethane dimethacrylate (UDMA) are organic monomers that can be released from dental composites into the oral cavity. Over specific concentrations, they can act as endocrine disruptors or cause toxic effects. The purpose of this work is to develop and validate an analytical method to determine BPA, Bis-GMA, TEGDMA, and UDMA monomers released from synthetic dental resins in artificial saliva. The method was validated before its application to new hybrid ceramic materials used in computer-aided design and computer-aided manufacturing (CAD/CAM) restorations to determine the release of monomers in various time intervals (e.g., 24 h, and 7, 14, 30, and 60 days), both in methanolic solutions, as well as in artificial saliva. Chromatographic analysis was performed isocratically on a Perfect Sil Target ODS-3 analytical column (250 mm × 4.6 mm, 5 µm) with CH3CN/H2O, 58/42% v/v as mobile phase within 23 min. The developed method was validated in terms of selectivity, linearity, accuracy, and precision.

Novel Urethane-Dimethacrylate Monomers and Compositions for Use as Matrices in Dental Restorative Materials.

In this study, novel urethane-dimethacrylate monomers were synthesized from 1,3-bis(1-isocyanato-1-methylethyl)benzene (MEBDI) and oligoethylene glycols monomethacrylates, containing one to three oxyethylene groups. They can potentially be utilized as matrices in dental restorative materials. The obtained monomers were used to prepare four new formulations. Two of them were solely composed of the MEBDI-based monomers. In a second pair, a monomer based on triethylene glycol monomethacrylate, used in 20 wt.%, was replaced with triethylene glycol dimethacrylate (TEGDMA), a reactive diluent typically used in dental materials. For comparison purposes, two formulations, using typical dental dimethacrylates (bisphenol A glycerolate dimethacrylate (Bis-GMA), urethane-dimethacrylate (UDMA) and TEGDMA) were prepared. The monomers and mixtures were tested for the viscosity and density. The homopolymers and copolymers, obtained via photopolymerization, were tested for the degree of conversion, polymerization shrinkage, water sorption and solubility, hardness, flexural strength and modulus. The newly developed formulations achieved promising physico-chemical and mechanical characteristics so as to be suitable for applications as dental composite matrices. A combination of the MEBDI-based urethane-dimethacrylates with TEGDMA resulted in copolymers with a high degree of conversion, low polymerization shrinkage, low water sorption and water solubility, and good mechanical properties. These parameters showed an improvement in relation to currently used dental formulations.

HPLC characterization of two resins used in removable prosthodontics: ProBase® hot and ProBase® cold

Introduction: Denture base acrylic resins release residual monomers as a result of an incomplete polymerization [1]. Due to its toxic effects on cells and constant contact with the oral mucosa, it is important to analyze the composition of these resins [2]. Organic solvents can mimic the erosive and acidic action of food and beverages and to penetrate resins’ polymeric matrix [3]. According to ISO 10993-5 (1999), to ensure the release of monomers, specimens must remain for at least 24 hours in contact with the solvent. High Performance Liquid Chromatography (HPLC) is the most efficient method to identify these components [3]. The aim of this study is to identify the monomers released by two denture base acrylic resins. Materials and methods: Specimens of self-cured resin ProBase® Cold and heat-polymerized resin ProBase® Hot were prepared according to the manufacturer’s instructions and placed in contact with an organic solvent by the sink-in method. The elution of Hydroxyethyl Methacrylate (HEMA), Methyl Methacrylate (MMA), Triethylene Glycol Dimethacrylate (TEGDMA) and Urethane Dimethacrylate (UDMA) monomers was evaluated by HPLC 0 hours (t0) and 24 hours (t24) after placing the samples in an oven at 37 °C. Results: The four studied monomers were found in both resins’ structures. Self-cured resin ProBase®Cold released higher concentrations of residual monomers compared to heat-polymerized resin ProBase® Hot (ρ = 0.021). TEGDMA and UDMA monomers were not released by acrylic resin ProBase® Hot at t0. Discussion and conclusions: t0 was evaluated in order to study the monomer release once the acrylic denture is placed into the patient’s mouth, at the dentist appointment. The results agree with Bayraktar et al. who stated that self-curing resins release higher ammounts of residual monomers when compared with heat polymerized acrylic resins [4]. Given the toxic effects of each monomer, we may assume that using acrylic resin ProBase® Hot on acrylic dentures is more beneficial to the patient when compared to ProBase® Cold.

Preparation of low shrinkage stress Bis-GMA free dental resin composites with a synthesized urethane dimethacrylate monomer

A new urethane dimethacrylate TMA was synthesized through a typical urethane reaction. TMA was used to replace 1,6-bis(methacryloxy-2-ethoxycarbonyl- amino)-2,4,4- trimethylhexane (UDMA) in UDMA based composite partially or totally to prepare TMA containing composites. Critical properties of TMA containing composites were investigated. 2,2-bis[4(2-hydroxy-3-methacryloy- propyloy)phenyl]propane (Bis-GMA) based and UDMA based composites were used as references. FT-IR and 1H-NMR confirmed the structure of TMA. All of experimental dental resin composites had the similar double bond conversion (p > 0.05). With a certain amount of TMA, TMA containing composites could have lower volumetric shrinkage (p < 0.05) and shrinkage stress (p < 0.05) than control groups. Water sorption, solubility, flexural strength and modulus of TMA containing composites were not worse than those of control groups. All of TMA containing composites and UDMA based composite had the same fracture toughness (p > 0.05), which was higher than that of Bis-GMA based composite (p < 0.05). TMA has potential as Bis-GMA substitute to prepare Bis-GMA free dental resin composites with low shrinkage stress.

TEGDMA and UDMA monomers released from composite dental material polymerized with diode and halogen lamps.

More than 35 substances released from composite fillings have been identified. Among these, basic monomers and the so-called co-monomers are most often reported. The substances released from polymer-based materials demonstrate allergenic, cytotoxic, genotoxic, mutagenic, embryotoxic, teratogenic, and estrogenic properties. The aim of this study was to measure the amounts of triethylene glycol dimethacrylate (TEGDMA) and urethane dimethacrylate (UDMA) monomers released from composite dental fillings to citrate-phosphate buffer with the pH of 4, 6, 8 after 24 h and 6 months from the polymerization. Ten samples for each polymerization method had been made from the composite material (Filtek Supreme XT, 3M ESPE, St. Paul, USA), which underwent polymerization using the following lamps: halogen lamp (Translux CL, Heraeus Kulzer, Hanau, Germany) (sample H) and diode lamp (Elipar Freelight 2, 3M ESPE), with soft start function (group DS) and without that function (group DWS). It has been demonstrated that the type of light-curing units has a significant impact on the amount of TEGDMA and UDMA released. The amount of UDMA and TEGDMA monomers released from composite fillings differed significantly depending on the source of polymerization applied, as well as the pH of the solution and sample storage time. Elution of the monomers from composite material polymerized using halogen lamp was significantly greater as compared to curing with diode lamps.

Effect of PEG Content on the Mechanical Properties of Bis-GMA/TEGDMA/UDMA Dental Resin Composites

In this study urethane dimethacrylate (UDMA) based dental resin materials were synthesized. Urethane methacrylate oligomers (UDMO) were synthesized via a radical chain growth polymerization mechanism using polyethylene glycol (PEG) in order to improve the mechanical properties, without adding a solvent in the reaction medium. The structure of the new monomer and oligomer were confirmed by FT-IR and 1H-NMR spectra. The results of FT-IR analysis indicated that the addition of PEG as plasticizer in the urethane methacrylate dental material in the adequate molar ratio (isophorone diisocyanate : HEM (2-hydroxyethyl methacrylate) : PEG = 2:2:1) improve the isocyanate double bond consumption. The Elastic strength (MPa) and Young’s Modulus of bending (MPa) were measured using a three-point bending set up. Urethane dimethacrylate monomer without PEG was used as control group. The results showed that PEG containing UDMO resins had lower Young’s Modulus: 2984 MPa and 2537 MPa (for 40s irradiation time) and Elastic strenght: 77 MPa and 51 MPa than UDMA derived resin: 3270 MPa respectively 90 MPa for all irradiation times (20 and 40 seconds).

Hybrid nanocomposites prepared by in situ photopolymerization using photoinitiator-modified montmorillonite

Abstract A series of hybrid nanocomposite coatings were prepared by UV curing of the urethane dimethacrylate monomers with various amounts of photoinitiator-modified montmorillonite (1, 3 and 5 wt.%, respectively). First, two different types of free-radical generating photoinitiators, a Type I – Irgacure 2959 (alpha cleavage type) and a Type II – benzophenone derivative (hydrogen abstraction type) were synthesized and bounded on Cloisite Na + layers. The homogeneous thin films were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), UV–vis spectrophotometry, thermogravimetric analysis (TGA) and mechanical testing. The XRD pattern of organic/MMT nanocomposite with 3 wt.% PI-1-MMT (Type I) hybrid photoinitiator displays a small peak at 6.36° (1.39 nm) characteristic to an intercalated structure, while in the XRD diffraction spectra of polymeric nanocomposites with PI-2-MMT (Type II) photoinitiator, no diffraction peaks were visible, suggesting the formation of an exfoliated structure. These outcomes were further confirmed by TEM and UV analyses, and can be attributed to the binding pathways (grafting/intercalation) of the photoinitiator molecules on the nanoclay surface. Also, the in situ photogeneration of silver nanoparticles (5 ÷ 10 nm diameter) triggered by photoinitiator-MMT systems was proved, when small well dispersed Ag NPs were formed.

Comparative Study of Structure-Property Relationships in Polymer Networks Based on Bis-GMA, TEGDMA and Various Urethane-Dimethacrylates.

The effect of various dimethacrylates on the structure and properties of homo- and copolymer networks was studied. The 2,2-bis-[4-(2-hydroxy-3-methacryloyloxypropoxy)phenyl]-propane) (Bis-GMA), triethylene glycol dimethacrylate (TEGDMA) and 1,6-bis-(methacryloyloxy-2-ethoxycarbonylamino)-2,4,4-trimethylhexane (HEMA/TMDI), all popular in dentistry, as well as five urethane-dimethacrylate (UDMA) alternatives of HEMA/TMDI were used as monomers. UDMAs were obtained from mono-, di- and tri(ethylene glycol) monomethacrylates and various commercial diisocyanates. The chemical structure, degree of conversion (DC) and scanning electron microscopy (SEM) fracture morphology were related to the mechanical properties of the polymers: flexural strength and modulus, hardness, as well as impact strength. Impact resistance was widely discussed, being lower than expected in the case of poly(UDMA)s. It was caused by the heterogeneous morphology of these polymers and only moderate strength of hydrogen bonds between urethane groups, which was not high enough to withstand high impact energy. Bis-GMA, despite having the highest polymer morphological heterogeneity, ensured fair impact resistance, due to having the strongest hydrogen bonds between hydroxyl groups. The TEGDMA homopolymer, despite being heterogeneous, produced the smoothest morphology, which resulted in the lowest brittleness. The UDMA monomer, having diethylene glycol monomethacrylate wings and the isophorone core, could be the most suitable HEMA/TMDI alternative. Its copolymer with Bis-GMA and TEGDMA had improved DC as well as all the mechanical properties.

The novel semi-biodegradable interpenetrating polymer networks based on urethane-dimethacrylate and epoxy-polyester components as alternative biomaterials.

This paper presents the pilot study aimed at the development of new full interpenetrating polymer networks based on urethane- dimethacrylate and biodegradable epoxy-polyester as the proposition of new biomaterials with gradually emerging porosity. The urethane-dimethacrylate monomer was obtained from 4,4'-methylenebis(phenyl isocyanate) and tetraethylene glycol monomethacrylate. The redox-initiating system was employed for its radical polymerization. The epoxy-polyester was produced by oxidation of the polyester, synthesized from succinic anhydride and allyl glicydyl ether. It was cured in a step-growth process with biogenic, aliphatic amine - spermidine. The mixtures of both monomers with adequate curing agents were room temperature polymerized. The hardened materials were characterized for damping behavior and dynamic modulus, hardness, water sorption, the course of hydrolytic degradation as well as the morphology - before and during the degradation process. The cured materials revealed the nonporous, dense morphology. In the hydrolytic environment, the epoxy-polyester network degraded and the porous urethane-dimethacrylate scaffold remained. The epoxy-polyester appeared to prevent the urethane-dimethacrylate from attaining a high degree of conversion, even if the polymerization rate and the molecular mobility of the latter one are higher than those of the epoxy-polyester. The most homogeneous material with the best physico-mechanical properties was obtained when the urethane-dimethacrylate content was smaller than the epoxy-polyester content, respectively 25 and 50 wt%. The system presented in this work could be useful in tissue engineering, where at the beginning of the tissue regeneration process it would meet the implant mechanical properties and then would deliver its porosity, facilitating the tissue regeneration process.

Synthesis of a novel tertiary amine containing urethane dimethacrylate monomer (UDMTA) and its application in dental resin

A novel tertiary amine containing urethane dimethacrylate monomer UDMTA was synthesized with the aim of replacing Bis-GMA as one component of dental restorative materials. The structure of UDMTA was confirmed by FT-IR and (1)H-NMR spectra. UDMTA was incorporated into Bis-GMA/TEGDMA (50wt%/50wt%) resin system to replace Bis-GMA partly and totally. Double bond conversion, polymerization volumetric shrinkage, water sorption and solubility, flexural strength and modulus of UDMTA containing resin formulations were studied with neat Bis-GMA/TEGDMA resin formulation as a reference. Results showed that UDMTA could be used as a coinitiator in photocurable dental resin, UDMTA containing resin had higher double bond conversion and lower polymerization shrinkage than that of Bis-GMA/TEGDMA resin, and the UDMTA containing copolymer had higher flexural strength and flexural modulus than Bis-GMA/TEGDMA copolymer. When UDMTA was used to replace more than 25wt% of Bis-GMA, the obtained copolymer had higher water sorption and solubility. The optimized resin composition is by replacing 25wt% of Bis-GMA in Bis-GMA/TEGDMA (50/50 by wt%), for the prepared resin had the best comprehensive properties.

Preparation and luminescent properties of ZnO:Ga(La)/polymer nanocomposite

Abstract Composite material, consisting of nanosized ZnO:Ga(La) embedded in a transparent polymer matrix was prepared. ZnO:Ga(La) was synthesized via photo induced precipitation from aqueous solution containing zinc formate, hydrogen peroxide and gallium nitrate or lanthanum acetate. Solid phase was calcined at 1100 °C to obtain crystalline ZnO:Ga(La) powder (crystallite size ∼ 50 nm) and further processed in reducing atmosphere (H2/Ar) at 800 °C. Resulting material features intensive excitonic luminescence under X-ray excitation, with distinct maximum at ∼392 nm. No defect related luminescence in visible spectral range was observed. Nanocomposite material was then prepared as follows: ZnO:Ga(La) nanopowder was homogeneously dispersed in the solution of urethane dimethacrylate monomers, and the fast UV-induced polymerization was subsequently employed for preparation of optically transparent polyurethane matrix with embedded nanopowder. Radioluminescence properties of prepared nanocomposite are qualitatively similar to those of ZnO:Ga(La) nanopowder.