Poly(N-isopropylacrylamide)
Poly(N-isopropylacrylamide) (variously abbreviated PNIPA, PNIPAAm, NIPA, PNIPAA or PNIPAm) is a temperature-responsive polymer that was first synthesized in the 1950s. It can be synthesized from N-isopropylacrylamide which is commercially available. It is synthesized via free radical polymerization and is readily functionalized making it useful in a variety of applications.
It forms a three-dimensional hydrogel when cross-linked with N,N’-methylene-bis-acrylamide (MBAm) or N,N’-cystamine-bis-acrylamide (CBAm). When heated in water above 32 °C (90 °F), it undergoes a reversible lower critical solution temperature (LCST) phase transition from a swollen hydrated state to a shrunken dehydrated state, losing about 90% of its volume. Since PNIPA expels its liquid contents at a temperature near that of the human body, PNIPA has been investigated by many researchers for possible applications in tissue engineering and controlled drug delivery.
History
The synthesis of poly(N-isoproylacrylamide) first began with the synthesis of acrylamides monomer by Sprecht in 1956. In 1957, Shearer patented the first application for what would be later identified as PNIPA for the use as a rodent repellent. Early work was piqued by theoretical curiosity of the material properties of PNIPA. The first report of PNIPA came in 1968, which elucidated the unique thermal behavior in aqueous solutions. The 1980s marked an explosion in interest in PNIPAs with the realization of potential applications due to its unique thermal behavior in aqueous solutions.
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by Inara George
No Poem
by: Inara GeorgeYou’re no poem once you open your mouth
I never like what you say
A carnation to cover your lips
When you speak I fall away
The exceptions are few in between
I spend time just trying to forget
Away, will you fall away
Let’s pretend that we've never met
Keep yourself within yourself
For all that you say it never gets better
In yourself within yourself
If I was you I wouldn’t talk, I’d just keep dancing
If all your moves were words
And backsteps were things you’ve denied
You’ve said, that’s right, your dead
I’m dumb, but not deaf and blind
Keep yourself within yourself
For all that you say it never gets better
In yourself within yourself
If I was you I wouldn’t talk, I’d just keep dancing
Keep yourself within yourself
For all that you say it never gets better
In yourself within yourself
If I was you I wouldn’t talk, I’d just keep dancing