Commercial Monomers Research Articles

Multilayered architectured ceramic panels with weak interfaces: energy absorption and multi-hit capabilities

Combining high strength and high toughness still remains a challenge in engineered materials. With the aim of improving the toughness of high-strength ceramics, multilayered architectured ceramic panels were developed inspired by natural materials such as nacre and conch shell. These panels were manufactured by stacking laser-engraved architectured ceramic tiles and commercial monomer Surlyn or Ethylene-vinyl acetate (EVA) resins. The mechanics of the multilayered architectured ceramics was investigated both numerically and experimentally by subjecting them to out-of-plane quasi-static and impact loads. Digital image correlation (DIC), computed radiography technique, micro-CT scanning and 3D laser scanning microscopy were used for multiscale damage assessment during and after loading. The finite element analysis was performed using ANSYS LS-DYNA to model the quasi-static and impact responses and to investigate the effects of architectural parameters on the energy absorption and multi-hit capabilities of architectured ceramic panels. It was found that the multilayered ceramic panels with optimized architectures showed up to 20% and 48% improvements in energy absorption performance in quasi-static testing and impact loading, respectively, with only a 5–10% stiffness reduction compared to plain ceramics. The deformation analysis showed localized failure in the architectured ceramics (opposed to the plain ones) and improved impact resistance of architectured ceramics originating mostly from the energy dissipation due to the plastic deformation in adhesives (up to 35%) as well as the frictional energy dissipation (up to 55%) upon sliding of the tiles, mechanisms that are absent in plain ceramics.

Multiblock copolymers of sulfonated PSU/PPSU Poly(ether sulfone)s as solid electrolytes for proton exchange membrane fuel cells

Sulfonated multiblock copolymers composed of Polysulfone (PSU) and Polyphenylsulfone (PPSU) poly(ether sulfone) segments (SPSU/SPPSU) are synthesized for the first time by polycondensation in a “one-pot two-step synthesis” of commercial monomers, followed by sulfonation reaction with trimethylsilyl chlorosulfonate (TMSCS). Both segments are responsible for proton conductivity, although the PSU block has greater affinity to be sulfonated. Even though no microphase separation is detected, the resulting ionomers exhibit good mechanical properties due to the non-sulfonated blocks remaining and to the high molecular weights of the ionomers. The chemical structure is confirmed by 1H-NMR, 19F-NMR and FTIR analysis. The degree of sulfonation (0.93–1.58) is determined from the IEC values and 1H-NMR spectra. In situ through-plane proton conductivity measured on the MEAs is 34.1 mS cm−1 at 70 °C. A maximum power density of 400 mW cm−2, a current density of 1100 mA cm−2 and outstanding thermo-mechanical stability, these proton-conducting membranes can therefore be implemented in PEMFC.

Physical properties and cytotoxicity of antimicrobial dental resin adhesives containing dimethacrylate oligomers of Ciprofloxacin and Metronidazole

ObjectiveAntimicrobial oligomers synthesized from ciprofloxacin (CF) and metronidazole (MN) were investigated for their potential use in dental adhesives. MethodsSusceptibility of the cariogenic bacterium Streptococcus mutans UA159 to CF, MN, and CF/MN combination was evaluated. Hydrolytic stability and drug release from the oligomers was studied in buffer and simulated human salivary esterase conditions. Cytotoxicity of films with 15wt% drug oligomers co-polymerized with commercial monomers were assessed using human gingival fibroblasts (HGFs). In-house adhesives were prepared and characterized for viscosity. Polymerized films were analysed for gel content and water swelling. Interfacial fracture toughness (KIC) of composites bonded to dentin by either a 2 or 3-step etch-and-rinse approach using the in-house formulated adhesives was measured. ResultsThe respective minimum inhibitory concentration for CF and MN against S. mutans was 0.7 and 2400μg/mL, with the combination having an additive effect (0.35μg/mL CF with 1200μg/mL MN). Antibiotics were released upon hydrolysis of the oligomers. Films containing the drug oligomers were not cytotoxic against HGFs. Replacing 2-hydroxyethyl methacrylate with the drug oligomers increased the viscosity of the experimental adhesives, reduced gel content, and decreased swelling of films in water. Antimicrobial adhesives demonstrated bonding to dentin with interfacial KIC values comparable to the in-house control in the 2-step application, and with slightly lower KIC values in the 3-step approach. SignificanceThe antimicrobial oligomers can be incorporated into dental adhesive systems using formulations that show comparable fracture toughness to commercial materials, and may provide a means to deliver local antimicrobial drug release at the marginal interface.

Investigation of accelerated aging of lignin-containing polymer materials

This paper presents the results of an accelerated aging test of biocomposites containing kraft lignin, where the resistance of the materials against humidity and light exposure was investigated. Low molecular weight lignin, modified with methacrylic anhydride (LWL-Met), was copolymerized with two commercial monomers: styrene (St) and methyl methacrylate (MMA). The biocomposites were obtained by a bulk polymerization method using α,α′-azoiso-bis-butyronitrile (AIBN) as a free radical polymerization initiator. The Shore D hardness of the obtained materials was determined before and after aging test. The changes in the chemical structures of polymers, as the result of aging were analyzed by using the attenuated total reflection Fourier transform infrared (ATR/FT-IR) spectroscopy method. The thermal behavior and stability of the obtained materials were investigated by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The surface topography was determined using the optical topography method to evaluate the changes on the surface of synthesized materials resulted from accelerated aging. Application of modified lignin as a biocomponent in the polymerization process and its influence on the properties of the obtained materials before and after the accelerated aging test are discussed.

Polymers for Fluorescence Imaging of Formaldehyde in Living Systems via the Hantzsch Reaction.

Formaldehyde (FA) has been detected via the Hantzsch reaction for many decades. However, the Hantzsch reaction has been rarely used to detect FA in biological systems due to the disadvantages of small-molecule probes (including toxicity and poor water solubility). In this study, polymeric fluorescent probes were developed to resolve these issues associated with small molecules, and FA in living systems was successfully detected via the Hantzsch reaction. These water-soluble polymers were easily scaled-up (∼25 g) by radical polymerization using commercial monomers. These polymers exhibited similar, albeit better, sensitivity to FA compared to water-soluble small molecules, primarily indicative of the advantages of polymers for the detection of FA via the Hantzsch reaction. The polymer structures were highly biocompatible with the probes; thus, these polymers can effectively detect endogenous FA in cells or zebrafish in a safe manner. This result confirmed the superiority of polymers in safety as biocompatible materials. This study highlights a straightforward method for exploring probes for the detection of FA in living systems. It offers functional polymers for bioimaging and extends the application scope of the Hantzsch reaction, reflecting the utility of a broad study of organic reactions in interdisciplinary fields as well as possible key implications in organic chemistry, analytical chemistry, and polymer chemistry.

Investigation of the electrochemical properties of poly(3,4-ethylenedioxypyrrole) films electrodeposited from aqueous solutions

Poly(3,4-ethylenedioxypyrrole) films on gold substrate were prepared by electropolymerization of ethylenedioxypyrrole monomer (EDOP) under potentiodynamic conditions in aqueous sodium sulfate solutions. The aim of the work was to characterize the gold | poly(3,4-ethylenedioxypyrrole) electrodes in aqueous sulfuric acid solutions and to compare the results with those of other studies that investigated similar systems. However, the experimental results obtained for the PEDOP modified electrodes significantly deviated from the expectations based on studies with similar systems. According to the results, two distinct types of polymer films were formed depending on the storage history of the monomer solutions. By using “fresh” monomer solutions polymer films with nearly ideal capacitive behavior were obtained and almost rectangular-shaped cyclic voltammograms could be observed in a rather broad potential range. Impedance spectra revealed that the charge transfer resistance between the substrate and the film was low. According to the SEM images the polymer layer on the gold substrate was relatively smooth with some small and short cracks. In contrast, working with “old” monomer solution that was not properly stored, the shapes of the cyclic voltammograms recorded at the Au | PEDOP | 0.1 M sulfuric acid (aq) electrode exhibited two peaks, a reduction peak at about −0.2 V vs. SSCE and an oxidation peak close to 0.2 V vs. SSCE, and the charge transfer resistances were considerably higher than those estimated for the electrode prepared using “fresh” monomer solutions. SEM images showed that the surface of the polymer film was extremely rough, with several wrinkles, creases and large cracks. This behavior was quite unexpected, because the two types of samples were prepared in the same way and only the storage histories of the two commercial monomer solutions were different.

Accessible microwave synthetized conjugated poly(azomethine‐pyridine) network and its metal complexes for CO2conversion

ABSTRACTA conjugated crosslinked polyazomethine containing pyridine units (PAM‐Py) was prepared from two commercial monomers, 2,6‐diaminopyridine and isophthaldehyde, under microwave heating in only 30 min. Taking advantage of its thermal and chemical stability, porosity (SBETof 192 m2/g), insolubility, and ability to coordinate metals through the pyridine or imine N atoms, ruthenium‐, aluminum‐, iron‐, and cobalt‐poly(azomethine‐pyridine) complexes (PAM‐PyM) were prepared. The resulting metal polymers were evaluated as heterogeneous catalysts for the cycloaddition of CO2to epoxides yielding selectively the corresponding cyclic carbonates. All heterogeneous catalysts showed an extraordinary effectiveness with very high yields of epoxide conversion (up to 98%), turnover numbers up to 7425, and were reused at least five times without loss in catalytic activity. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem.2018,56, 1946–1952

Commercial Monomer Availability Leading to Missed Opportunities? Anion-Exchange Membranes Made from meta-Vinylbenzyl Chloride Exhibit an Alkali Stability Enhancement

Benzyltrimethylammonium-type anion-exchange polymers are common in alkali membrane fuel cells and water electrolysers but they suffer from degradation under alkaline conditions. Radiationgrafted anion-exchange membranes exhibit an alkali stability enhancement when made using non-commercial meta-only vinylbenzyl chloride (VBC) monomer, compared to the use of commercially available para-only or meta/para-mixed VBC isomers. We hypothesize a mechanism on why the use of meta-VBC eliminates AEM degradation via chain scission.

Synthesis and characterization of Ciprofloxacin-containing divinyl oligomers and assessment of their biodegradation in simulated salivary esterase

ObjectiveTwo leading causes contributing to dental restoration replacement are the marginal breakdown at the composite/dentin interface and secondary caries mediated by bacteria. The objective of the present study was to synthesize oligomers which incorporated enhanced bio-stability but would also be able to generate antimicrobial function if they underwent degradation. MethodsStability was incorporated into the oligomers by generating structural features that would physically hinder the availability of hydrolytically sensitive groups in the oligomers. As a proof-of concept for the antibacterial feature, antimicrobial function was achieved by covalently incorporating Ciprofloxacin (CF) into the backbone of cross-linking divinyl oligomers (referred to as EDV and HLH-CFPEG). The hydrolytic stability of the oligomers was studied in simulated human salivary esterase and compared to the commercial monomer 2,2-bis[4(2-hydroxy-3-methacryloxypropoxy)-phenyl]propane (BisGMA). ResultsBoth drug oligomers were found to be significantly more stable than BisGMA. Upon degradation, both drug oligomers released CF differentially in free form. Polymer synthesis from resin formulations containing 15wt% HLH-CFPEG showed a high degree of vinyl group conversion and gel content, and under hydrolytic conditions showed the release of CF during a 28-day monitoring study period. SignificanceHLH-CFPEG can be used in dental resin adhesive systems for local delivery of CF to the marginal interface. Minimizing the growth of Streptococcus mutans at the marginal site can improve longevity by reducing esterase activity derived specifically from S. mutans.

Thermal and spectral analysis of copolymers with sulphur groups

The paper presents the synthesis, structure and polymerization of S-phenyl 2-methylprop-2-enethioate (PSM). This compound was prepared in the reaction of thiophenol with methacryloyl chloride. The obtained PSM was purified on the chromatographic column. Chemical structure of the monomer was confirmed by spectroscopic methods (ATR–FTIR, GC–MS, 1H and 13C NMR). Next bulk polymerization of PSM with styrene (St) or methyl methacrylate (MMA) was performed. In this way, linear copolymers were obtained. The number and mass average molar mass of the obtained copolymers were determined by gel permeation chromatography (GPC). Additionally, crosslinked copolymers of the commercial monomer S,S′-thiodi-4,1-phenylene bis(thiomethacrylate) (DMSPS) under the same conditions were synthesized. The influence of thiol monomers on the physico-chemical properties of the obtained copolymers was determined. Thermal properties of the synthesized materials were investigated by means of DSC and TG/DTG.

Permeable Protein-Loaded Polymersome Cascade Nanoreactors by Polymerization-Induced Self-Assembly.

Enzyme loading of polymersomes requires permeability to enable them to interact with the external environment, typically requiring addition of complex functionality to enable porosity. Herein, we describe a synthetic route toward intrinsically permeable polymersomes loaded with functional proteins using initiator-free visible light-mediated polymerization-induced self-assembly (photo-PISA) under mild, aqueous conditions using a commercial monomer. Compartmentalization and retention of protein functionality was demonstrated using green fluorescent protein as a macromolecular chromophore. Catalytic enzyme-loaded vesicles using horseradish peroxidase and glucose oxidase were also prepared and the permeability of the membrane toward their small molecule substrates was revealed for the first time. Finally, the interaction of the compartmentalized enzymes between separate vesicles was validated by means of an enzymatic cascade reaction. These findings have a broad scope as the methodology could be applied for the encapsulation of a large range of macromolecules for advancements in the fields of nanotechnology, biomimicry, and nanomedicine.

Biodegradation Studies of Novel Fluorinated Di-Vinyl Urethane Monomers and Interaction of Biological Elements with Their Polymerized Films.

The monomeric components of resin composites in dental restorative materials are susceptible to hydrolysis in the oral cavity. The main objective of this study was to assess the bio-stability of fluorinated urethane dimethacrylates and determine the nature of fluoro-chemistry interactions with protein and bacterial adhesion (both sources of hydrolytic activity) onto cured resin. Degradation studies were performed in the presence of either albumin (in a mildly alkaline pH) or cholesterol esterase (CE). The surface chemistry of the polymers was assessed by water contact angle measurements, pre- and post- incubation with albumin. Adhesion of Streptococcus mutans to cured resin was investigated. The fluorinated monomers were more stable against degradation when compared to the commercial monomer bisphenol A-diglycidyl methacrylate (BisGMA). While fluorinated monomers showed hydrolytic stability with respect to CE, all fluorinated monomers underwent some degree of degradation with albumin. The fluoro-chemistry did not reduce protein and/or bacterial adhesion onto the surface, however post incubation with albumin, the fluorinated surfaces still presented hydrophobic character as determined by the high contact angle values ranging from 79° to 86°. These monomers could potentially be used to increase the hydrophobicity of polymeric composites and provide a means to moderate esterolytic degradation associated with the monomeric component of the polymers within the oral cavity.

Synthesis and properties of hydroxide conductive polymers carrying dense aromatic side-chain quaternary ammonium groups

A series of hydroxide conductive polymers QTBMs carrying dense aromatic side-chain quaternary ammonium groups has been synthesized by using a new monomer of 3,3′-di(3″,5″-dimethylphenyl)-4,4′-difluorodiphenyl sulfone and other commercial monomers via polycondensation reaction, and subsequent bromination, quaternization and alkalization. The chemical structures of the ionomers were confirmed by 1H- and 13C-NMR spectroscopy. Water uptake, swelling ratio, hydroxide conductivity, the number of bonded water per ammonium group (λ), volumetric ion exchange capacity (IECVwet), mechanical and thermal properties, and chemical stability were systematically evaluated for the series of QTBMs membranes. QTBMs showed IECs ranging from 1.02 meq·g−1 to 2.11 meq·g−1; in particular, QTBM-60 membrane with the highest IEC (2.11 meq·g−1) had very high hydroxide ion conductivity of 131.9 mS·cm−1 at 80 °C, which was attributed to the well assembled nano-channels with distinct phase separation evidenced by small-angle X-ray scattering (SAXS). It was found that the hydrated QTBMs membranes were mechanically stable with moderate water uptakes and swelling ratios, high chemical stability under the harsh alkaline conditions. This work provides a facile way to prepare anion exchange membranes (AEMs) with high performances for the application in alkaline fuel cells.

Ultrafast Digital Printing toward 4D Shape Changing Materials.

Ultrafast 4D printing (<30 s) of responsive polymers is reported. Visible-light-triggered polymerization of commercial monomers defines digitally stress distribution in a 2D polymer film. Releasing the stress after the printing converts the structure into 3D. An additional dimension can be incorporated by choosing the printing precursors. The process overcomes the speed limiting steps of typical 3D (4D) printing.

Photocrosslinkable polymer based on 4-(3-(2,4-dichlorophenyl)-3-oxoprop-1-enyl) phenylacrylate: synthesis, reactivity ratio, and crosslinking studies

Abstract The acrylate monomer was synthesized by two step process. 2,4-dichloro-1-ene(4-hydroxyphenyl)phenone (DHP) was synthesized using 4-hydroxy benzaldehyde and 2,4-dichloro acetophenone. 4-[3-(2,4-dichloro-phenyl)3-oxoprop-1-en-1-yl]phenylacrylate (DCP) was prepared by reacting DHP with acryloyl chloride. The synthesized monomer was copolymerized with 2-hydroxyethyl acrylate and styrene using solution polymerization technique. Monomer and polymers were characterized by IR, NMR and UV techniques. The average molecular weight of the polymer was around 4000 g/mol. First and second decomposition temperature of the polymers was around 320 °C and 430 °C, respectively. The reactivity ratio of the polymers was calculated by Fineman-Ross, Kelen-Tudos and extended Kelen-Tudos methods. The synthesized monomer has been less reactive than the commercial monomer. The rate of photocrosslinking increased from 39 % to 99 % due to the using of copolymerization technique.

Synthesis of poly(arylene ether ketone) containing phenylsulfonic acid pendant for proton exchange membrane

A series of phenylsulfonic acid–containing poly(arylene ether ketone) (psa-PAEK) were synthesized via polycondensation from 2-(4-methoxy)phenylhydroquinone and other commercial monomers, followed by postsulfonation approach under mild reaction conditions. Controlled substituted sites and the degree of sulfonation were realized using quantities of 2-(4-methoxy)phenylhydroquinone. Giving the psa-PAEK can be soluble in common organic solvents such as Dimethylsulfoxide, purity ≥99.5% (DMSO, Sinopharm Chemical Reagent Co., Ltd, Shanghai, China), NMP, 1-Methyl-2-pyrrolidinone purity ≥99.0% (NMP, Sinopharm Chemical Reagent Co., Lted, Shanghai, China), and N,N-dimethylacetamide, purity ≥99.0% (DMAc, Sinopharm Chemical Reagent Co., Lted, Shanghai, China). The tough and transparent polymer membrane was prepared by the solution casting method, which exhibited excellent mechanical properties and high proton conductivities. The tensile stress at maximum load and elongation at break of these membranes are 28.3–34.1 MPa and 101–126% in dry state, respectively. The proton conductivities of these membranes were higher than 10−2 S cm−1 at room temperature in water. Especially, the psa-PAEK-90 with ion exchange capacity of 1.62 mequiv. g−1 exhibited the proton conductivity of 176 mS cm−1 at 80°C in water. The clear microphase separation morphology was observed by small-angle X-ray scattering, which is a powerful evidence to explain their high conductive behaviors. These results suggest that the psa-PAEK membranes have great potential as a candidate membrane for proton exchange membrane fuel cell applications.

Highly Phase Separated Aromatic Ionomers Bearing Perfluorosulfonic Acids by Bottom-up Synthesis: Effect of Cation on Membrane Morphology and Functional Properties

Proton-conducting aromatic-based ionomers bearing superacid side chains are usually synthesized by polymer postmodification, which does not allow controlling ion exchange capacity and ionic group distribution along the ionomer and, thus, its chemical structure and functional properties. Bottom-up approach overcomes this problem. Here, we report the preparation of a novel ionic monomer and its polycondensation with commercial monomers. The obtained random ionomers are the first to show high phase separated organization at macro-, micro-, and nanoscale, common to the reference proton-conducting material Nafion. Additionally, membranes were cast from the solutions of ionomers in their Li+ and K+ forms in order to study the cation’s influence on both morphology and performance of the materials. The difference in ionic domain organization, depending on the initial cationic form of the ionomers, was reported for the first time. The proposed materials show superior proton conductivity than Nafion, especially at ...

Synthesis and biodegradation of di-vinyl monomers containing different antimicrobial agents for use in dental adhesive systems

Event Abstract Back to Event Synthesis and biodegradation of di-vinyl monomers containing different antimicrobial agents for use in dental adhesive systems Yasaman Delaviz1* and J Paul Santerre1, 2* 1 University of Toronto, Institute of Biomaterials and Biomedical Engineering, Canada 2 University of Toronto, Faculty of Dentistry, Canada Introduction: More than 50% of dental restorations placed annually are resin composites[1]. However, these materials experience significant biological breakdown in the oral cavity that is believed to be facilitated by oral bacteria which migrate within the margin between the tooth and restorative material. Ciprofloxacin (CF) and Metronidazole (MN) are two antimicrobial agents with potential to manage oral bacterial in the margin environment[2],[3] Previous work reported on the synthesis of CF derived vinyl monomers for adhesives [4]. The objectives of the current work are to synthesize an antimicrobial di-vinyl monomer that will release MN upon hydrolytic degradation, and to formulate adhesive systems containing a combination of both MN and CF derived di-vinyl monomers. Methods: A lysine/hydroxyl-methyl methacrylate (HLH) derivative was synthesized [5]. Using carbodiimide chemistry, the hydroxyl moiety of MN was coupled to HLH acidified ester, yielding HLH-MN. The monomer was characterized by nuclear magnetic resonance. Biodegradation studies (0.1mM) of HLH, HLH-MN and commercial Bisphenol A-glycidyl methacrylate (BisGMA) (n=9, repeated 3 times) were carried out at 37⁰C in buffer or enzyme solution (containing cholesterol esterase activity and pseudocholinesterase activity) for 4 days and solutions characterized by high performance liquid chromatography (HPLC)[5],[6]. Preliminary formulations of CF and MN derived monomers were light cured (1min) using camphorquinone/2-(dimethyl-amino) ethyl methacrylate photo-initiator system, with commercial monomers BisGMA and 2-hydroxyethyl methacrylate (HEMA)[4]. Gel contents were determined and cell toxicity compared using human gingival fibroblasts. Results and Discussion: HLH-MN structure was confirmed by 1H-NMR (Fig 1). The amount of MN released was not significantly different between the buffer or enzyme condition (Fig 2a), whereas it was for BisGMA[7]. HLH-MN was more stable than BisGMA under enzymatic conditions (Fig 2b). The rate of MN released in buffer (4.091 µM/day, r2 = 0.99) was much greater than CF (0.039 µM/day, r2 = 0.86). The linkage between the backbone and MN is an ester while CF is coupled via a more stable amide. This will play to the advantage of each of the drugs relative to minimum inhibitory concentrations (MICs) for Streptococcus mutans, (0.7 µg/mL for CF vs 700 µg/mL for MN). The gel content for cured adhesives with weight percent values for MN:CF:Hema:BisGMA of 5:10:30:55; 10:5:30:55, and 15:15:15:55 were 99.2% (±0.5), 99.0% (±0.7) and 96.0% (±2.8), respectively. These high conversion states are anticipated to yield good cell compatibility in on-going work. Figure 1. 1H-NMR(CDCl3, 400MHz) of HLH-MN, the drug MN is highlighted in blue. Figure 2. Degradation (a) by-products MN and BisHPPP released and (b) remaining monomer in solution, under buffer (DPBS) or enzyme conditions. Conclusion: HLH-MN, which polymerizes with a high degree of cross-linking, is more hydrolytically stable in comparison to BisGMA and releases MN upon degradation. On-going work is assessing the efficacy of the drug release for the combination systems and determining an optimal formulation of the two drug monomer adhesive system with respect to mechanical, chemical and biological stability. The authors would like to thank Dr. Meilin Yang for his scientific input and expertise in chemistry; NSERC CGS and NSERC Discovery Grant #360520

Biodegradation of dental adhesive polymers containing ciprofloxacin derived monomers

Event Abstract Back to Event Biodegradation of dental adhesive polymers containing ciprofloxacin derived monomers Yasaman Delaviz1* and J Paul Santerre1, 2* 1 University of Toronto, Institute of Biomaterials and Biomedical Engineering, Canada 2 University of Toronto, Faculty of Dentistry, Canada Introduction: Despite their popularity[1], resin composites have limited longevity in the oral cavity due to chemical hydrolysis that is believed to be facilitated in part by bacterial hydrolases within the margin of the tooth and restorative material [2][3]. To overcome this challenge, a pro-biochemical approach is being investigated where a drug monomer (DM) is introduced into resin adhesives, enabling the release of antimicrobial agents if the materials are degraded by salivary enzymes. The objective of this study was to assess the degradation of a formulated adhesive with 15wt% DM, and compare it to a control (Bis-Hema) containing the commercial monomers Bisphenol A glycidyl methacrylate (BisGMA) and 2-hydroxyethyl methacrylate (HEMA). Methods: The antibiotic ciprofloxacin (CF) is chemically coupled to the backbone of a di-vinyl lysine monomer, referred to as HLH. The DM is synthesized by covalently coupling a CF/polyethylene glycol (PEG) complex via a pendant acid group on HLH[2]. Adhesive samples (2mm D, 1mm H) were formulated and light cured (1 min/side) in Teflon moulds using 0.5wt% camphorquinone and 1wt% dimethylamino-ethyl methacrylate as initiator system (Tab 1). Gel content (in dichloromethane) and swell ratio (in water) were determined (n=5) after 48 hrs of incubation. Contact angles (n=15, repeated 3 times) were measured by means of a goniometer using deionized water (Tab 1). Biodegradation studies (n=9, repeated 3 times) were performed by by incubating with either DPBS or enzyme solution (containing cholesterol esterase activity and pseudocholinesterase activity), for 28 days[3]. Enzyme activity was maintained by daily replenishment following previously established protocols[3],[4]. Degradation by-products were isolated by high performance liquid chromatography (HPLC). Table 1. Summarizing composition, physical property and contact angle of the three formulations (1:BisHEMA, 2:DM, 3:HLH) used in the biodegradation study;±SD. Results and Discussion: DM is about ~50x more hydrolytically stable than BisGMA[2], however the addition of the DM increased the amount of BisHPPP (terminal degradation by-product of BisGMA) released in DPBS (Fig 1a). In the presence of enzyme, there is no significant difference in the amount of BisHPPP released between the control and the DM containing formulation, but degradation is 3x higher than with DPBS (Fig 1b). Interestingly, the non-PEG precursor (i.e. HLH formulation) significantly enhanced stability (i.e. lower BisHPPP), suggesting that the lysine chemistry promotes stability. The HLH formulation has the lowest water swell ratio (Tab 1), which would also predispose it to less hydrolysis. There was no significant difference in the CF released for buffer vs enzyme (Fig 1c), suggesting that the enzyme has limited access to the pseudo-amide linkage, possibly due to steric hindrance from the bulky pendent structure of CF[5],[6]. Figure 1. Terminal BisHPPP released under (a) buffer and (b) enzyme condition. (c) Terminal CF released from DM formulation for buffer and enzyme condition. Values significantly different are labeled as * (p<0.05), ±SD. Conclusion: While the HLH component contributes to stability of the adhesive, the PEG element enables CF release via simple hydrolysis when BisGMA undergoes degradation in an enzymatic environment. On-going work is investigating the efficacy of the released drug in the presence of streptococcus mutans. NSERC CGS and NSERC Discovery Grant #360520

Synthesis and characterization of linear dendritic homo and copolymers acrylated behera amine

A co-polymerizable dendron of first generation synthesized from behera amine was homopolymerized and copolymerized with commercial monomers such as styrene, methyl methacrylate, and N-vinyl pyrrolidone. Characterization of the co-polymers was performed and it was found with the help of FT-IR and proton and carbon NMR that copolymerizable dendron, ACTES (ACrylated TriESter, first-generation dendron of acrylated behera amine) was incorporated in the co-polymer chains. Besides, the reactivity ratio pairs of the ACTES monomer with both styrene and n-vinyl pyrrolidone were determined. The reactivity ratio pair for ACTES and MMA could not be determined by neither gravimetrically nor with NMR. After experiments and calculations, the reactivity ratio pair for styrene and ACTES was found to be rst = 0.27 and rac = 0.44 and for NVP and ACTES rnvp = 0.36 and rac = 1.01. By utilization of the reactivity ratio of ACTES, “Q” and “e” values were determined in order to be able to draw some conclusions about the reactivity behavior during copolymerizations. “Q” = 1.152 and “e” = 0.66 were found with respect to styrene as reference. These values indicates the steric effect of ACTES was more dominant in copolymerizations.