Speciality polymers.pptx

speciality polymers are the class of some high perfomance polymers ,including plastic,polymers,fluids,membranes,smart hydrogels,and elastomers that are designed to meet the critical requirement that engineers face everyday in key industries including plastic, automobiles, aeronautics, smart devices, health care, pharmacy, energy production and storage. this article is a short but diversified study of post grad. students in the area of speciality polymers, the types and applications in engineering, technology ,life sciences and research. it include diverce applications of iconic polymer metal composites liquid crystal polymers ,synthetic polymer membranes, smart hydrogels, and dendritic polymers.

1. Speciality polymers chitosan

2. Chitin; a brief history ⚫ 1811 Chitin was first discovered by Professor Henri Braconnot , who isolated it from mushrooms and name it " Fungine ". 1823 Antoine Odier found chitin while studying beetle cuticles and named "chitin" after Greek word "chiton" (tunic, envelope). 1859 Rought discovered chitosan, a derivative of chitin. ⚫ 1920s Production of chitin fibers from different solvent systems. 1930s Exploration of synthetic fibers. 1950s The structure of chitin and chitosan was identified by X-ray diffraction, infrared spectra, and enzymatic analysis. 1970s "Re-discovery" of the interest in chitin and chitosan. ⚫ 1977 1 international conference on chitin/chitosan

3. What is chitin? Chitin is a natural polysaccharide.Structure similar to cellulose with hydroxyl group replaced by acetamino group.N -acetyl-glucosamine units in B-(1-4) linkage. Found in the exoskeleton as well as in the internal structure of shells of shrimp .and crustaceans.. Chitin has 3 polymorphic form:a-chitin , B-chitin, y-chitin

4. Chitosan Chitosan a biopolymer derived from crab shells which is insoluble in common organic solvents has been converted to the organo soluble N- phthaloylchitosan ( Phch )by reaction with phthalic anhydride to dimethyl formide (DMF) Chitin is a highly abundant carbohydrate polymer occuring primarily in crab shells. Chitosan has been shown to help plant's absorb fertilisers better, releasing nitrogen and acting as a biostimulant for the crop, leading to increased yields. Coastal gardener's have long known about the benefits of mixing crustaceans shells with leaves, bark and other mulch to make fertilisers . Crab shells were used to produce chitosan via the three stages of deprotenisation , deminiralisation and deacetylation using sodium hydroxide and hydrochloric acid. Chitosan have several beneficial property such as bio compatibility, bio degradability, hydrophilicity and anti bacterial. The % of chitin present in crab shell is 15-30%. Specialty polymer provide fast track customized solutions from high flow specialised formulations for small complex geometry to replacing metal in structural components where strength rigidity and aesthetic are important.

5. Preperation of chitosan • Produced commercially by deacetylation of chitin. • The degree of deacetylation (%DD) can be determined by NMR spectroscopy.the %DD in commercial chitosan ranges from 60 to 100%.

6. Properties of Chitosan • Unique characteristics of chitin and chitosan: Biocompatible Biodegradable Non- toxicRemarkable affinity to proteins Ability to be functionalized Renewable Abundant Antimicrobial properties Mechanism still unknown hypotheses:- binding to cell-wall phospholipids of Gram-negative bacteriamodification of cell-wall permeability and loss of material inhibition of certain enzyme

7. Water binding capacity-Measured using a modified method of Knorr.It carried out by weighing a centrifuge tube containing 0.5 g of sample, adding 10 ml of water and mix it on a vortex mixer for 1 min.. Contents were left at ambient temperature (29°C) for 30 min. After the supernatant was decanted, the tube was weighed again.

8. Fat binding capacity- . It also measured by using a modified method of Knorr.⚫ Carried out by weighing a centrifuge tube containing 0.5 g of sample, adding 10 mlof oil (soybean oil) and mixing on a vortex mixer for 1 min. The contents were left at ambient temperature for 30 min. After the supernatantdecanted , the tube was weighed again

9. Viscosity- • The viscosity of chitosan increases with increasing chitosan concentration, decreasing temperature, and increasing degree of deacetylation

10. Moisture content and Solubility .It absorbs moisture from atmosphere.Particle size distribution: <30 mm ⚫ determined by the gravimetric method Solubility- Sparingly soluble in water. • Practically insoluble in ethanol and other organic solvents. Solubility is affected by degree of deacetylation. PH: 4.0-6.0 Density: 1.35-1.40 g/cm³ Glass transition temperature: 203°

11. Reactive moieties of Chitosan- OH: esterification, etherification, oxidation, elimination, protection reactions. NH2: amidation , reduction, mono-, di- and trialkylation (electrophile subsitution ), protection reactions.

12. Biomedical Applications Wound DressingWound dressings are used to protect wound skin form insult, contamination and infection Chitin-based wound dressings -Increase dermal regeneration - Accelerate wound healing - Prevent bacteria infiltration - Avoid water loss ⚫ Chitin surgical threads - strong, flexible, decompose after the heals Anticoagulation Anticoagulation is essential for open- heart surgery and kidney dialysis Preventing blood from clotting during the surgery Sulfated chitosan derivatives havegood anticoagulant activity

13. Biomedical applications Tissue Engineering Tissue engineering research is based on the seeding of cells onto porous biodegradable matrix Chitosan can be prepared in porous forms permitting cell growth into complete tissue Orthopedic Applications Bone is a composite of soft collagenand hard hydroxyapatite (HA) Chitin-based materials are suitable candidate for collagen replacement (chitin-HA composite) Mechanically flexible, enhanced bone formation Temporary artificial ligaments for the knee joint

14. Drug delivery Hydrogels Hydrogels are highly swollen, hydrophilic polymer networks that can absorb large amounts of water pH-sensitive hydrogels have potential use in site- specific drug delivery to gastrointestinal tract (GI) Chitosan hydrogels are promising in drug deliverysystem Microcapsules- Microcapsule is defined as a spherical empty particle with size varying from50 nm to 2 mm Chitosan-based microcapsules aresuitable for controlled drug release.

15. Biotechnology applications Enzyme immobilization Specific, efficient, operate at mild conditions Unstable, sensitive after isolation and purification Chitin and chitosan-based materials are suitableenzyme immobilizers- Biocompatible- Biodegradable-High affinity to protein -Reactive functional group Gene Delivery Viral gene delivery/Non-Viral gene delivery Viral: high transfection efficiency, dangerous Non-Viral: low transfection efficiency, safer Chitosan-DNA complexes can be optimized to enhance the transfection efficiency