13 research outputs found
An investigation of siloxane cross-linked hydroxyapatite–gelatin/copolymer composites for potential orthopedic applications
Causes of bone deficiency are numerous, but biomimetic alloplastic grafts provide an alternative to repair tissue naturally. Previously, a hydroxyapatite-gelatin modified siloxane (HAp-Gemosil) composite was prepared by cross-linking (N, N′-bis[(3-trimethoxysilyl)propyl]ethylene diamine (enTMOS) around the HAp-Gel nanocomposite particles, to mimic the natural composition and properties of bone. However, the tensile strength remained too low for many orthopedic applications. It was hypothesized that incorporating a polymer chain into the composite could help improve long range interaction. Furthermore, designing this polymer to interact with the enTMOS siloxane cross-linked matrix would provide improved adhesion between the polymer and the ceramic composite, and improve mechanical properties. To this end, copolymers of L-Lactide (LLA), and a novel alkyne derivatized trimethylene carbonate, propargyl carbonate (PC), were synthesized. Incorporation of PC during copolymerization affects properties of copolymers such as molecular weight, Tg, and % PC incorporation. More importantly, PC monomers bear a synthetic handle, allowing copolymers to undergo post-polymerization functionalization with graft monomers to specifically tailor the properties of the final composite. For our investigation, P(LLA-co-PC) copolymers were functionalized by an azido-silane (AS) via copper catalyzed azide-alkyne cycloaddition (CuAAC) through terminal alkyne on PC monomers. The new functionalized polymer, P(LLA-co-PC)(AS) was blended with HAp-Gemosil, with the azido-silane linking the copolymer to the silsesquioxane matrix within the final composite
The role of temperature in forming sol–gel biocomposites containing polydopamine
The processing temperature has a big impact on the mechanical properties of HAp-Gemosil composites containing polydopamine
The Lantern Vol. 63, No. 1, Fall 1995
• The Birthday Celebration • Surprise! Surprise! • Oregold • Future of Parenthood #2 • Seeds • How I Spent My Summer Vacation • Random Scenes From 1/2 Hour at Work • Life in the Coal Mines • Driveway • Midnight in the Court of Kings • The Black Quadrilateral • People I Hate to See, But Refuse to Dismiss • Metropolized • Poetry in Motion • Dream #3 • Rhythms • Mercykilling • Untitled • Lupine Lord • At the Bottom of the Cup • House of Commons • Poetry I Can\u27t Standhttps://digitalcommons.ursinus.edu/lantern/1147/thumbnail.jp
Interaction of microwaves with carbon nanotubes to facilitate modification
The present invention is directed toward methods of crosslinking carbon nanotubes to each other using microwave radiation, articles of manufacture produced by such methods, compositions produced by such methods, and applications for such compositions and articles of manufacture. The present invention is also directed toward methods of radiatively modifying composites and/or blends comprising carbon nanotubes with microwaves, and to the compositions produced by such methods. In some embodiments, the modification comprises a crosslinking process, wherein the carbon nanotubes serve as a conduit for thermally and photolytically crosslinking the host matrix with microwave radiation
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Use of Microwaves to Crosslink Carbon Nanotubes
Patent relating to the use of microwaves to crosslink carbon nanotubes
Investigation of Dopamine Analogues: Synthesis, Mechanistic Understanding, and Structure–Property Relationship
Dopamine,
perhaps the simplest molecule that covalently links catechol
and amine, together with its derivatives, has shown impressive adhesive
and coating properties with its polymers. However, the scope of the
molecules is rather limited, and the polymerization mechanisms are
still elusive. We designed a general synthetic scheme and successfully
synthesized a series of dopamine analogues with different alkyl chain
lengths between the catechol and amine. Taking these new dopamine
analogues, together with the molecular systems that have separate
catechol and alkyl amine, we show that having both catechol and amine
in the molecular system, whether covalently linked via an alkyl chain
or not, is sufficient to polymerize under a similar reaction condition
to that of dopamine polymerization. However, the time-dependent UV–vis
characterization of the individual polymerization indicates that the
polymerization for individual molecular systems likely proceeds via
different reaction intermediates, depending on the length of the alkyl
chain and whether there is a covalent linkage. Interestingly, whereas
the covalent linkage via an alkyl chain is not necessary for showing
the adhesive property, it is required to achieve the impressive coating
property. Our results offer new insights into the design and synthesis
of dopamine analogues for future applications, as well as a further
mechanistic understanding of the polymerization of these dopamine
analogues
Deformity correction of the midfoot/hindfoot/ankle
The correction of the deformed arthritic foot and ankle is a complicated and somewhat controversial topic. After conservative methods fail, there is a wide range of possible bony procedures and arthrodesis that maybe performed. The appropriate work up and understanding of the pathomechanics is vital to the correct choice of procedures to correct these deformities. Once the work up and procedure selection is done, the operation must also be technically performed well and with efficiency, as most often the condition is corrected with a variety of procedures. This article discusses some of the most common procedures necessary to fully correct deformity of the midfoot, hindfoot, and ankle. This article will also discuss the authors\u27 technique and pearls
An investigation of siloxane cross-linked hydroxyapatite–gelatin/copolymer composites for potential orthopedic applications
Causes of bone deficiency are numerous, but biomimetic alloplastic grafts provide an alternative to repair tissue naturally. Previously, a hydroxyapatite-gelatin modified siloxane (HAp-Gemosil) composite was prepared by cross-linking (N, N′-bis[(3-trimethoxysilyl)propyl]ethylene diamine (enTMOS) around the HAp-Gel nanocomposite particles, to mimic the natural composition and properties of bone. However, the tensile strength remained too low for many orthopedic applications. It was hypothesized that incorporating a polymer chain into the composite could help improve long range interaction. Furthermore, designing this polymer to interact with the enTMOS siloxane cross-linked matrix would provide improved adhesion between the polymer and the ceramic composite, and improve mechanical properties. To this end, copolymers of L-Lactide (LLA), and a novel alkyne derivatized trimethylene carbonate, propargyl carbonate (PC), were synthesized. Incorporation of PC during copolymerization affects properties of copolymers such as molecular weight, T(g), and % PC incorporation. More importantly, PC monomers bear a synthetic handle, allowing copolymers to undergo post-polymerization functionalization with graft monomers to specifically tailor the properties of the final composite. For our investigation, P(LLA-co-PC) copolymers were functionalized by an azido-silane (AS) via copper catalyzed azide-alkyne cycloaddition (CuAAC) through terminal alkyne on PC monomers. The new functionalized polymer, P(LLA-co-PC)(AS) was blended with HAp-Gemosil, with the azido-silane linking the copolymer to the silsesquioxane matrix within the final composite. These HAp-Gemosil/P(LLA-co-PC)(AS) composites were subjected to mechanical and biological testing, and the results were compared with those from the HAp-Gemosil composites. This study revealed that incorporating a cross-linkable polymer served to increase the flexural strength of the composite by 50%, while maintaining the biocompatibility of HAp-Gemosil ceramics