This document discusses the use of radiation for the preparation of hydrogels. It begins by defining hydrogels as polymer networks that are hydrophilic and absorbent, similar to natural tissue. Two common types of radiation used are gamma rays and electron beams. Common polymers used in preparation include PVAL, PVP, PEO, and PAA. The principle of preparation involves irradiating an aqueous polymer solution, which causes cross-linking between polymer chains and formation of a gel. The method involves alternately irradiating the polymer solution with gamma rays and electron beams to create radicals and new covalent bonds, cross-linking the polymers into a semi-solid hydrogel. Applications of hydrogels include use in bi

1. P R E S E N T E D B Y :
V I S H A K H A K U M A R
1 3 M S G 0 0 2 5
Use of Radiation for the
Preparation of Hydrogels

2. Hydrogel / Biogel
 Hydrogel is a network of polymer chains that are
hydrophilic, sometimes found as a colloidal gel in
which water is the dispersion medium.
 They are highly absorbent and possess a degree of
flexibility very similar to natural tissue.
 Nowadays for medical purposes, a special type of
hydrogel called ‘stimuli responsive hydrogel’ is being
prepared which has the ability to respond to changes
in temperature, pH, and pressure by adding suitable
ions to it during preparation.

3. Gamma Rays Electron Beams
 Electromagnetic
radiation
 Highly ionizing and
have high energy levels
 Can easily pass through
human tissues and
cause damage
 Can be stopped by
using lead shields
 Observed as a stream
of electrons in a
vacuum tube
 Can pass through thin
metal foils like
aluminium
 Prolonged exposure is
harmful but not to the
extent of gamma rays
Types of radiation used in hydrogel preparation

4. Common Polymers Used in Biogel Preparation
 PVAL- Poly Vinyl Alcohol
 PVP- Poly Vinyl Pyrrolidone
 PEO- Poly Ethylene Oxide
 PAA- Poly Acrylic Acid
 The choice of polymer depends on the extent of
water retention capacity required by the hydrogel.

5. Principle of Hydrogel Preparation
 When a polymer is irradiated in aqueous solution, it
leads to cross-linking of the macromolecular chains
forming larger, branched, soluble polymers.
Continuation of the linking and cross-linking process
results in increasing the size of the branched polymer
with decreasing solubility and ultimately forms a gel.
 This system does not require either monomers or cross-
linking agents and unwanted processes like homografting
of monomer on a polymer chain that may lead to
branched structures is lessened. Hydrogels formed in
this way are also suitable for biomedical use with no need
of further purification.

6. Method
 An aqueous solution of the polymer of choice is taken in
a suitable heat resistant vessel and irradiated alternately
with gamma rays and electron beams.
 This results in the formation of macroradicals, mostly
hydrated electrons, hydroxyl radicals and hydrogen
atoms.
 The macroradicals undergo recombination which
initiates the cross-linking reaction and new covalent
bonds are formed between the polymer chains.
 Cross-linking results in the formation of a semi-solid
substance. Irradiation is continued after time intervals
until the gel obtains a favourable texture and to ensure
maximum bonds have been formed.

7. Overall Method

8. Applications

9. References
 Hydrogel: Preparation, characterization, and applications-
Enas M. Ahmed; July 2013
 Radiation and industrial polymers- A. Bhattacharya;
September 2010
 Radiation synthesis and modification of polymers for
 Biomedical Applications ; Final results of a co-ordinated
research project- J.M. Rosiak, I. Janik, S. Kadlubowski, M.
Kozicki, P. Kujawa, P. Stasica, P. Ulanski, Z.S. Nurkeeva, M.T.
Razzak, D. Darwis, Zainuddin, Sukirno- 1996 to 2003
 Radiation Chemistry In The Field Of Biomaterials- Adolphe
Chapiro
 Synthesis of hydrogels by irradiation of polymers in aqueous
solution - J.M. Rosiak, P. Ulan ski
 Hydrogels and their medical applications- Janusz M.
Rosiak, Fumio Yoshii b

10. Acknowledgement