Add Your Title
advertisement
PowerPoint Template Add your company slogan Contents Click to edit text styles Edit your company slogan 1. Click to add Title 2. Click to add Title 3. Click to add Title 4. Click to add Title pH-Sensitive Smart Polymeric nanofibers Click to edit text styles Edit your company slogan The composition of pH sensitive polymeric nanofibers contain pendant acidic ( e.g, carboxylic and sulfonic Acids) or basic (e.g, ammonium salts) groups that either accept or release protons in response to changes To environmental pH. Polyacrylic acids, poly(2-ethylacrylic acid), poly(2-propylacrylic acid) and Polysulphonamides(derivatives of p-aminobenzenesulfonamide) are few examples of polyacids (anionic polymers). Similarly, poly(N, N-diakyl aminoethyl methacrylates), poly(lysine), poly(ethylenimine), and Chitosan represent cationic polyelectrolytes. pH sensitive macromolecules dissociate to give polymeric Ions after dissolving on ionizing solvent. Repulsion between similar charges on the polymeric chains results in chain expansion when ionized in a suitable solvent. When unionized in the case of a poor solvent and hydrophobic polymer they collapse into globules and also precipitate from solution. They interplay between hydrophobic surface energy and electrostatic repulsion between charges dictates the behavior of the polyelectrolytes. Since the degree of an aqueous medium, smart polymers dramatically change conformation in response to minute changes in the pH of aqueous environment. Various works have been performed on PMMA based polymers. Microparticles prepared of poly(methacrylic Acid-g-ethylene glycol) P(MAA-g-EG) loaded with insulin exhibited unique pH-responsive characteristics in Which interpolymer complexs were formed in acidic media and dissociated in neutral/basic environments. Consequently, insulin release from the gel was significantly retarded in acidic media while rapid release occurred under neutral/basic conditions. Copolymer networks of poly(methacrylic acid)grafted with Poly(ethylene glycol) with reversible pH-dependent swelling behavior, due to the formation of interpolymer Complexs between protonated pendant acid groups and the etheric groups on the graft chains, has been Developed. Gels containing equimolar amounts of MAA/EG exhibited lesser swelling at lower pH. The pH of The pH of the swelling solution affected the average network mesh size. In vitro release of insulin from P(MAA-g-EG)gels containing PEG grafts indicated a significant release of insulin as the gel decomplexed. Hot Tip Click to edit text styles Edit your company slogan Composite membranes from nanoparticles of poly(N-isopropylacrylamide-co-methacrylic acid)of various NIPAAm:MAA ratios dispersed in a matrix of a hydrophobic polymer have been investigated. Temperature Responsive Polymeric Fibers Polymers sensitive to temperature changes are the most studied class of environmentally sensitive polymers as they have potential applications in the biomedical field. This type of systems exhibit a critical solution temperature (typically in water) at which the phase of polymer and solution is changed in accordance with their composition. Those systems exhibiting one phase above certain temperature and phase separation below it possess an upper critical solution temperature (UCST). On the other hand, Polymer solution that appear as monophasic below a specific temperature and biphasic above it generally exhibit the so-called lower critical solution temperature(LCST). LCST are the type of polymers having number of applications. The typical example is poly(N-isopropylacrylamide) (PNIPAAm)that presents a LCST at 32 in water solution. Examples thermal responsive poly(4-vinylbenzyl chloride)-block-poly(glycidyl methacrylate)-garft-poly(NIsopropylacrylamide) (PVBC-b-PGMA-g-PNIPAM) nanofibers by the combined technology of reversible additionfragmentation chain transfer (RAFT) polymerization atom transfer radical polymerization(ATRP) ,electrospinning, and “click chemistry”. PVBC-b-PGMA-g-PNIPAM nanofibers exhibit a good resistance to solvents and thermal-responsive charater to the environment, having a hydrophobic surface at 45 (warer contact angle ~ 140)and having a hydrophilic surface at 20 (warer contact angle ~30). Below that temperature the polymer is soluble as the hydrophilic interactions, due to hydrogen bonding, are predominant, whereas a phase separation occurs above the LCST(cloud point) due to predomination of hydrophobic interactions. LCST values of polymers are found to be controlled by the alkyl group bound to the nitrogen atom.Other type of temperature sensitivity is based on the intermolecular association as in the Case of Pluronics or Poloxamers, where hydrophobic associations of PPO blocks lead to the formation of micelle Structure above CMT(critical micelle temperature). N-alkylacrylamide monomers are mostly employed to obtain temperature snsitive polymers. These monomers are Synthesized by nucleophilic substitution reaction of acryl chloride with the suitable amine. Electrospinning of nanofiber: An Overview Click to edit text styles Edit your company slogan In recent years, polymers are processed by various techniques such as drawing(1),tempelate synthesis(2), phase Separation(3), self-assembly(4), electrospinning(5), etc. to prepare polymernanofibers from micron to nanometer Scale. The main idea is to bring reduced diameter of polymeric fibers so as to achieve outstanding characteristics Such as very large surface area to volume ratio, flexibilities in surface functionalities, and superior mechanical properties. (1)The drawing-in process is similar to dry spinning. Drawing method can be used to make one to one and very long Single nanofibers. However, this method is possible only for viscoelastic polymers that can undergo strong deformations while being cohesive enough to support the stresses developed during pulling. Similarly in the case of Template synthesis, a nanoporous membrane is used as a template to make nanofiber of solid(a fibril) or hollow(a tubule) shape. By this method nanometer tubules and fibrils of various raw materials such as electronically conducting polymers, metals, semiconductors, and carbons can be fabricated. But this method cannot one-by-one continuous nanofibers. (2) Phase separation is complex process consists of dissolution, gelatin, and extraction using a different solvent, freezing, and drying resulting in nanoscale porous foam. This process takes longer time to transfer the solid polymer into the nano-porous foam. (3) On the other hand, self-assembly is a process in which individual pre-existing components organize themselves into desired patterns and functions. However, the self-assembly is also a time Consuming process similar to that as phase separation/ [ Image information in product ] Title Image - CD: Infomedia2(os26) (PhotoDisc) Note to customers : This image has been licensed to be used within this PowerPoint template only. You may not extract the image for any other use. Hot Tip Click to edit text styles Edit your company slogan How do I incorporate my logo to a slide that will apply to all the other slides? On the [View] menu, point to [Master], and then click [Slide Master] or [Notes Master]. Change images to the one you like, then it will apply to all the other slides. [ Image information in product ] Title Image - CD: Infomedia2(os26) (PhotoDisc) Note to customers : This image has been licensed to be used within this PowerPoint template only. You may not extract the image for any other use. Hot Tip Click to edit text styles Edit your company slogan How do I incorporate my logo to a slide that will apply to all the other slides? On the [View] menu, point to [Master], and then click [Slide Master] or [Notes Master]. Change images to the one you like, then it will apply to all the other slides. [ Image information in product ] Title Image - CD: Infomedia2(os26) (PhotoDisc) Note to customers : This image has been licensed to be used within this PowerPoint template only. You may not extract the image for any other use. INTRODUCTION Click to edit text styles Edit your company slogan Response to stimulus is the basic principle of living systems. As life is made up of biopolymers such as carbohydrate, proteins and neuclic acids, functions of the living cells are regulated by these biopolymers which form the basis around for natural processes. Based on the lessons from nature, polymer scientists have been designing useful materials that respond to external stimuli such as light, temperature, PH, chemicals and electric field. Polymeric materials which respond by large changes due to small changes in the environments are referred as ‘stimuli respond polymers’ or ‘smart polymer’ or ‘intelligent polymers’ or ‘environment sensitive polymer’. Accordingly smart polymers have promising applications in the biomedical field as delivery systems of therapeutic agent, tissue engineering scaffolds, cell culture supports, bioseparation devices, sensors or actuators system. However, the goal of scientists is not only to mimic biological process but also to create novel species and discover new process. The environmental triggers behind these transitions could be change in temperature or PH shift, increase in ionic strength, presence of certain metabolic chemicals, addition of an oppositely charged polymer and magnetic field, and light or radiation forces have also been reported as stimuli for these polymers. Among the above, pH and temperature responsive polymers are main focus of polymeric scientists. Due to the very small diameter (nanometer scale) of the polymeric nanofibers obtained by electrospinning, the surface area to volume ratio of the fibers is significantly high. Also, the nonwoven mats formed from such nanofibers have very small pore sizes. However, the total porosity of the mats will still be very high. Hence, smart polymeric nanofibers can provide better cell penetration and growth so as to promote cell growth. Click to edit text styles Diagram Edit your company slogan 2000 2000.10 2000.10 2000.10 Add Your Text Add Your Text Add Your Text 2001 2001.10 2001.10 2001.10 Add Your Text Add Your Text Add Your Text 2002 2002.10 2002.10 2002.10 Add Your Text Add Your Text Add Your Text 2003 2003.10 2003.10 2003.10 Add Your Text Add Your Text Add Your Text Click to edit text styles Diagram Edit your company slogan Title Add your text ThemeGallery ThemeGallery is a Design Digital Content & Contents mall developed by Guild Design Inc. is a Design Digital Content & Contents mall developed by Guild Design Inc. Click to edit text styles Diagram Edit your company slogan Text Text Add Your Title Text Text Click to edit text styles Diagram Edit your company slogan Text Add Your Title Text Text •Text •Text •Text •Text • 1 2 3 4 5 Add Your Title Text Text Text Text Text Text •Text •Text •Text •Text • 1 2 3 4 5 Diagram Click to edit text styles Edit your company slogan Add Your Text Add Your Text Add Your Text Add Your Title Click to edit text styles Diagram Edit your company slogan Text Text Text Add Your Text Add Your Text Add Your Text Click to edit text styles Chart- PowerPoint2002 4th Qtr 20.4 31.6 3rd Qtr Edit your company slogan 43.9 90 2nd Qtr 27.4 1st Qtr 20.4 0 34.6 38.6 46.9 30.6 20 40 45 45.9 60 80 East 100 West 120 North 140 160 180 Click to edit text styles Diagram Edit your company slogan Add Your Text Add Your Text Add Your Text Add Your Text Add Your Text Add Your Text Add Your Text Add Your Text Click to edit text styles Diagram Edit your company slogan Add Your Text Add Your Text Add Your Text Add Your Text Text Add Your Text Add Your Text Click to edit text styles Marketing Diagram Edit your company slogan Add Your Title Add Your Title Add Your Title Title Click to add text Click to add text Click to add text Title Click to add text Click to add text Click to add text Title Click to add text Click to add text Click to add text Title Click to add text Click to add text Click to add text Title Click to add text Click to add text Click to add Click to edit text styles Diagram Edit your company slogan 1 2 3 ThemeGallery is a Design Digital Content & Contents mall developed by Guild Design Inc. ThemeGallery is a Design Digital Content & Contents mall developed by Guild Design Inc. ThemeGallery is a Design Digital Content & Contents mall developed by Guild Design Inc. Click to edit text styles Diagram 2001 Edit your company slogan 2002 2003 2004 Click to edit text styles Progress Diagram Phase 1 Edit your company slogan Phase 2 Phase 3 Click to edit text styles Block Diagram Edit your company slogan TEXT TEXT TEXT TEXT TEXT TEXT TEXT TEXT Click to edit text styles Table Edit your company slogan 90 45 34.6 46.9 45 38.6 46.9 46.9 34.6 27.4 38.6 38.6 90 27.4 2002 East 2003 West North 27.4 2002 2003 East West 2002 North Click to edit text styles 3-D Pie Chart Edit your company slogan TEXT TEXT TEXT TEXT TEXT TEXT Add your company slogan
