Jeffrey W. Stansbury - Academia.edu (original) (raw)

Papers by Jeffrey W. Stansbury

Chemistry of Materials, Jan 30, 2007

Photoinitiated polymerization of acrylates and methacrylates is currently being used for various ... more Photoinitiated polymerization of acrylates and methacrylates is currently being used for various applications including dental materials, contact lenses, coatings, polymeric membranes, stereolithography, and drug delivery applications. 1-5 Because of the wide variety of potential and current applications, development of high performance (meth)acrylates has been the focus of great interest. In the early 1990s, functionalization of an acrylate with certain secondary functional groups such as carbamates, carbonates, cyclic carbonates, ureas, and oxazolidones was discovered to lead to a dramatic enhancement in polymerization rate. 6-10

OSTI OAI (U.S. Department of Energy Office of Scientific and Technical Information), 2002

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Materials horizons, 2020

Semicrystalline polymeric materials possessing extraordinary mechanical properties were rapidly f... more Semicrystalline polymeric materials possessing extraordinary mechanical properties were rapidly fabricated using light from low viscosity liquids at room temperature.

Dental Materials, Jul 1, 1992

a-Methylene-~,-butyrolactone (MBL), which can be de-MBL much more polar than MMA. As a result, MB... more a-Methylene-~,-butyrolactone (MBL), which can be de-MBL much more polar than MMA. As a result, MBL has scribed as the cyclic analog of methyl methacrylate, exhibits almost no odor and very low volatility compared with MMA. greater reactivity in free radical polymerizations than conventional Another consequence of the greater polarity of MBL is that it methacrylate monomers. Unfilled resin formulations composed of serves as an excellent solvent for oligomers and non-cross-Bis-GMA/MBL or Bis-GMNTEGDMA/MBLwere light-cured. The linked polymers. This is analogous to the comparison of the effect of the more reactive methylene lactone monomer on solvent properties of diethy] ether, which is often used to mechanical properties and the degree of conversion of the poly-precipitate polymers and tetrahydrofuran, its cyclic countermers was examined. The infrared absorption bands for the part, which is an excellent solvent for a wide range ofpolymers. carbon-carbon double bonds of MBL and the methacrylate mono-Poly(MBL) produced by free radical initiation has a mers are well resolved and allow the conversion of each compo-glass transition temperature (%)of195°C (Akkapeddi,1979a) nent to be calculated individually. The incorporation of a small as compared with the (105°C) ~i'~ of atactic poly(MMA) (Lee amount of MBL (5 w/o) to Bis-GMA significantly increased the and Rutherford, 1975). The linear polymer also displays conversion; however, additional MBL (10to 30 w/o) did not further excellent solvent resistance as evidenced by its lack of increase the Bis-GMA conversion level. This appears to indicate solubility in common organic solvents such as chloroform and an incompatibility between MBL and the bulky Bis-GMA monomer, tetrahydrofuran. The high Tg and low solubility ofpo]y(MBL) Addition of 10 w/o MBL to Bis-GMA/TEGDMA (7:3) resulted in a are indicative of significant structural rigidity of the polymer cured resin with 71% methacrylate and 75% overall conversion chain. This can be attributed to the conformationally rigid efficiencies compared with the 57% conversion of the control ]actone rings which do not have the rotational freedom of the formulation. The diametral tensile and the transverse strengths pendant groups in poly(MMA). were approximately 10% greater for the MBL resin compared with In addition to these favorable properties, copolymerization the Bis-GMNTEGDMA control; however, these differences were studiesofMBLwithMMAhavedemonstratedthattheformer not statistically significant. The synthesis and polymerization of is a significantly more reactive monomer (Akkapeddi,1979b). several substituted methylene lactones was also studied. This increased reactivity of MBL compared with methacrylate monomers can be ascribed to a number of factors related to the

Journal of Biomedical Materials Research, 2004

The accurate and reliable characterization of the polymerization shrinkage stress is becoming inc... more The accurate and reliable characterization of the polymerization shrinkage stress is becoming increasingly important, as the shrinkage stress still is a major drawback of current dimethacrylate-based dental materials and restricts its range of applications. The purpose of this research is to develop a novel shrinkage stress measurement device to elucidate the shrinkage stress evolution of dental restorative composites while allowing for controlled sample deformation during the polymerization. Furthermore, the device is designed to mimic the clinically relevant cusp-to-cusp displacement by systematically adjusting the instrument compliance, the bonded surface area/unbonded area by sample geometry, and the total bonded area by sample diameter. The stress measurement device based on the cantilever beam de¯ection theory has been successfully developed and characterized using a commercial dental composite. It was shown that this device is a highly effective, practical and reliable shrinkage stress measurement tool, which enables its facile applications to the investigation of shrinkage stress kinetics of both commercial and experimental composites, as well as for probing various aspects that dictate shrinkage stress development.

Journal of Oral Rehabilitation, Dec 6, 2010

Self-adhesive resin cements were introduced to dentistry within the past decade but have gained r... more Self-adhesive resin cements were introduced to dentistry within the past decade but have gained rapidly in popularity with more than a dozen commercial brands now available. This review article explores their chemical composition and its effect on the setting reaction and adhesion to various substrates, their physical and biological properties that may help to predict their ultimate performance and their clinical performance to date and handling characteristics. The result of this review of self-adhesive resin cements would suggest that these materials may be expected to show similar clinical performance as other resin-based and non-resin based dental cements.

Macromolecular Chemistry and Physics, Feb 1, 2015

Macromolecules, Apr 23, 2021

Photocurable thiol-norbornene resins featuring triazole-embedded norbornene monomers were develop... more Photocurable thiol-norbornene resins featuring triazole-embedded norbornene monomers were developed, and the photopolymerized networks showed good to superior ductility in the glassy state with elo...

Macromolecules, Nov 18, 2021

Journal of Molecular Graphics & Modelling, Feb 1, 2011

Quantitative structure-activity relationships (QSAR) have been developed for the viscosity of per... more Quantitative structure-activity relationships (QSAR) have been developed for the viscosity of perfluoropolyalkyl ethers as a function of the carbon to oxygen ratio and the bending energy. These treatments permit the prediction of viscosity/temperature and viscosity/molecular weight profiles. Molecular structures have been determined for a series of perfluoropolyalkyl ethers using molecular mechanics.

Journal of The Mechanical Behavior of Biomedical Materials, Oct 1, 2017

Significant efforts have been expended to mitigate plasticizer migration from crosslinked methacr... more Significant efforts have been expended to mitigate plasticizer migration from crosslinked methacrylic and poly(vinyl chloride) polymer networks by synthesizing reactive plasticizers that can blend homogenously within the networks to reduce polymer property change, acute toxicity and downstream environmental effects of plasticizer migration with limited and varying amount of success. We hypothesized that appropriate thiol-functionalized nanogels synthesized using the same monomers as the parent network to generate highly compact, crosslinked structures will form thermally stable, homogenous networks and perform as optimal reactive plasticizers. Nanogels were synthesized via a thiol-Michael addition solution polymerization and incorporated at different mass ratios within a polyethylene glycol 400 urethane dimethacrylic monomer to form photo-crosslinked networks. While maintaining the inherent hydrolytic stability, thermal stability and biocompatibility of the parent matrix at ~ 99 % acrylic group conversion, the PEG400 urethane dimethacrylic-nanogel networks retained optical clarity with > 90 % visible light transmission at 20 wt % nanogel loading. The addition of the nanogels also enhanced the elongation of the parent matrix by up to 320 %, while a 37 °C reduction in glass transition temperature (ΔT g) and ≥ 50 % reduction in modulus was observed. A 52 % reduction in the shrinkage stress of the material was also noted. The results indicate that the application of thiolfunctionalized nanogels as plasticizers to alter the bulk properties of the parent matrix while mitigating plasticizer migration by covalently crosslinking the nanogels within the polymer matrix provides a simple yet efficient technique to generate network-specific plasticizers with the ability to alter targeted properties within polymers.

Polymer, Aug 1, 2020

This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Journal of Dental Research, Sep 23, 2014

Polymeric dental adhesives require the formation of densely crosslinked network structures to bes... more Polymeric dental adhesives require the formation of densely crosslinked network structures to best ensure mechanical strength and durability in clinical service. Monomeric precursors to these materials typically consist of mixtures of hydrophilic and hydrophobic components that potentially undergo phase separation in the presence of low concentrations of water, which is detrimental to material performance and has motivated significant investigation into formulations that reduce this effect. We have investigated an approach to network formation based on nanogels that are dispersed in inert solvent and directly polymerized into crosslinked polymers. Monomers of various hydrophilic or hydrophobic characteristics were copolymerized into particulate nanogels bearing internal and external polymerizable functionality. Nanogel dispersions were stable at high concentrations in acetone or, with some exceptions, in water and produced networks with a wide range of mechanical properties. Networks formed rapidly upon light activation and reached high conversion with extremely low volumetric shrinkage. Prepolymerizing monomers into reactive nanostructures significantly changes how hydrophobic materials respond to water compared with networks obtained from polymerizations involving free monomer. The modulus of fully hydrated networks formed solely from nanogels was shown to equal or exceed the modulus in the dry state for networks based on nanogels containing a hydrophobic dimethacrylate and hydrophilic monomethacrylate, a result that was not observed in a hydroxyethyl methacrylate (HEMA) homopolymer or in networks formed from nanogels copolymerized with HEMA. These results highlight the unique approach to network development from nanoscale precursors and properties that have direct implications in functional dental materials.

Journal of Dental Research, Mar 1, 1983

The reaction of vanillate esters dissolved in chelating agents with zinc oxide yields hard cement... more The reaction of vanillate esters dissolved in chelating agents with zinc oxide yields hard cementitious materials. Hexyl vanillate-EBA(o-ethoxybenzoic acid) mixed with ZnO-Al 2O3-hydrogenated rosin gives a high-strength, low water-soluble cement that does not inhibit polymerization and adheres to non-precious metals and composites.

Journal of Polymer Science Part A, Aug 13, 2009

The impact of secondary functionalities on the radical‐vinyl chemistry of monoacrylates character... more The impact of secondary functionalities on the radical‐vinyl chemistry of monoacrylates characterized by secondary functionalities that dramatically enhance their polymerization rate was elucidated utilizing experimental and computational techniques. Firstly, bulk interactions affecting the acrylate reactivity towards photopolymerization were removed by polymerizing at 5 wt % monomer in 1,4‐dioxane. Following deconvolution of bulk interactions impacting reactivity towards photopolymerization, a linear correlation between average polymerization rates and Michael addition reaction rate constants was observed on a logarithmic scale. This result indicates that the presence of the secondary functionality intramolecularly alters the monomer chemistry in a manner which impacts both of these distinct reaction types in a similar manner. These monomers exhibited reduced activation energies in both Michael addition and photopolymerization reactions as compared to hexyl acrylate. Reduction up to 20 ± 8 kJ mole−1was observed for Michael addition reactions and 12 ± 1 kJ mole−1 for photopolymerization reactions, thereby explaining the higher reactivity of the acrylates characterized by the secondary functionalities. Cyclic voltammetry experiments conducted to investigate the nature of the acrylic double bonds indicated that the rapidly polymerizing acrylates are more readily reduced as compared to traditional acrylates. Further, a distinct monotonic correlation of the irreversible cathodic peak potentials of the (meth)acrylates to photopolymerization and Michael addition reactivity was observed. The computationally estimated acrylic LUMO energies characterized by the secondary functionalities (−2.3 eV to −2.7 eV) were also found to be lower relative to hexyl acrylate (−2.2 eV). © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 4859–4870, 2009

Dental Materials, Jul 1, 2010

Objective. Stress development at the tooth/restoration interface is one of the most important rea... more Objective. Stress development at the tooth/restoration interface is one of the most important reasons for failure of adhesive restorations. The aim of this study was to evaluate the influence of BisGMA/TEGDMA (B/T) and UDMA/TEGDMA (U/T) ratios on polymerization stress (PS) and on the variables related to its development: degree of conversion (DC), polymerization maximum rate (Rp max), volumetric shrinkage (VS), elastic modulus (E), stress relaxation (SR) and viscosity of experimental composites.

INTRODUCTION x manufacturer' s instructions. Optimum casting conditions are accompanied by higher... more INTRODUCTION x manufacturer' s instructions. Optimum casting conditions are accompanied by higher precision (predictability i.e., smaller standard deviation) for the CV. A prime consideration in casting of dental alloys involves obtaining a satisfactory clinical fit of multiple unit, fixed, partial dentures (FPD's). This is of particular concern for nonprecious alloys which as a class are more difficult to join single units together by soldering. A study on factors affecting fit showed quite clearly that the use of an all wax sprui ng-runner bar system produced less distortion (better fit) than a pattern which is comprised of mixed materials, in wax and plastic. Effects of Porcel ai n/Alloy Interfacial Diffusion Zones on Thermomechanical Strain.