Page 217 - AWSAR 2.0

We have varied the polymer concentration, crosslinker concentration, crosslinker type, charge density and surfactant addition and studied its impact on mechanical strength of the hydrogels. Let me explain some important findings that we came across here. When polymer concentration was increased, the strength of the hydrogels also increased systematically. This is expected because as we increase the polymer concentration, the number of crosslinked junctions in the network also increase. Owing to this, the strength of the hydrogels increased. Next, we kept the polymer concentration constant and varied the crosslinker concentration. According to the theory, (A: Is there a name of the theory? Do you mean “Theoretically”) we know that when crosslinker concentration increases then there should be an increase in crosslinking points and the strength of the hydrogels should increase. But what we found was that this was only true till an optimal range.
After this range, it was seen that the strength of the hydrogels decreased.
“Next, we studied the
effect of different types of
crosslinkers. Three different
crosslinkers were used and
the effect of these crosslinkers
on the strength and structure
of hydrogels was examined.
The strength of the hydrogels
was seen to depend on the
type of crosslinkers used.
Some produced harder gels
as compared to others. So we
concluded that the crosslinking mechanism also plays a great role and by choosing a right crosslinker higher strength hydrogels can be produced. We also varied the charge density of the hydrogel. We saw that as the charge density of the hydrogel increased, the strength of the hydrogel decreased. We, thus, concluded that
Ms. Mithra K. || 193
increasing the charges in the hydrogel leads to a decrease in the strength, which may be because of increasing hydrophilicity. We also studied the effect of adding surfactants on the structure of hydrogels. We varied the surfactant concentration and surfactant type and studied its interaction with hydrogels. When surfactant concentration was varied the strength of the hydrogel decreased. We also saw that different types of surfactants had different effect on gel strength. The extent of interaction of surfactants with hydrogel varied with different surfactants. Some surfactants interacted to a greater extent than some surfactants in which the effect was negligible. This behaviour was seen to depend on the charge of the surfactant,” Kavya detailed
“All of this is quite interesting. We have gained so much knowledge on this material that now even we can give a lecture on it,” joked Priya.
“So what’s the principle behind this gel lifter,” asked Karan.
“It’s actually quite easy,” said Kavya. “You apply the gel on any rough surface and it captures the image. Then you have to photograph the image to get the fingerprint.”
“That was indeed easy,” said Priya. “Now we can easily solve the case once we get the fingerprint.”
“But before we leave we would like to know what else do you plan on doing?” said both
detectives in unison.
“Actually this is one part of the research.
We also study the diffusion mechanism inside hydrogels. As diffusion plays an important role in many of the natural processes like how nutrients and proteins move inside cells and tissues. So it is highly beneficial to study the
Usually ‘polymers’ are used to prepare hydrogels. A polymer is a long-chain molecule consisting of a unit, which is repeated thousands of times (‘mer’ means many times hence polymer). A hydrogel is formed when these polymers are knotted together through crosslinking.