Synthesis And Characterization Of Infrared Sensitive Poly (N-Isopropyl Acrylamide) Microgels

Environmental sensitive microgel is a special group in microgel family.Their state and performance can quick change or reaction with the change of temperature,light,PH value,and other environment factors.They are intelligent polymer materials.These materials can be used as the carrier of medicine for targeting release,or they can be used in the probe of various sensors.So,they have a broad prospect of application.This paper is focus on synthesis and characteristic research of these kinds microgels.First,a micro soap or soap free,free radical dispersion emulsion polymerization was used,and N-isopropyl acrylamide was used as main monomer,2-acrylamido-2-methyl-1-propanesulfonic acid was used as ionic comonomer,N,N'-methylene-bis-acrylamide as crosslinker to synthesize the microgel,in order to get a uniform size,regularly arrayed,temperature and infrared sensitive microgel.Test shows,the Low critical solution temperature was about 31.5?.The paper also proved the temperature and light sensitivity of the microgel by using a temperature gradient method to test the absorption and photo permeability of light.Second,add carboxyl group contained group comonomer,like acrylic acid as the comonomer,in order to make controlled particle sized PNIPAM microgel.Test results showed a temperature sensitivity of ~ 29 mK was achieved through the use of the hydrogel copolymer NPs with size of 120-nm,which is higher than big ones'.It means Small NPs have better IR sensitivity than large NPs.At the same time,with the carboxyl group comonomer added into the molecular chiain of the PNIPAM,it can be close combined on Au foil surface and get a kind of Monolayer-protected clusters(MPC)through esterification or amidation reaction.Nano Au foil has the property of Surface Plasmon Resonance(SPR).When it combined with PNIPAM microgel,a red shift phenomenon will appear with the changing of temperature.This phenomenon can also represent the environmental sensitive of PNIPAM.Test results showed SPR could also be detected,and the red shift could be found in the LCST temperature range.