Photonic Crystal Hydrogel Based On Acryloyl Phenylboronic Acid:Preparation And Saccharide Responsive Performance

Responsive photonic crystals have drawn great attention for their potential application prospectin physical or chemical sensors,intelligent display and optical devices.As an important research branch of photonic crystals,sugar-responsive photonic crystal hydrogel has been greatly developed in the last few decades,such as applied in carbohydrate concentration detection,carbohydrate identification and drug release.However,it still has obvious disadvantage in sugar-responsive photonic crystal hydrogel,for example,lower polymerization rate,poor stability,lower mechanical strength and so on.In order to solve these problems,we prepared a kind of free-standing Fe3O4@PVP/PNIPAM photonic crystals hydrogel film and found that it not only have thermoresponsive ability but also have sugar-responsive ability.The detail results are given as follow:Four kinds of acryloylphenylboronic acid were synthesized as monomers,and then these monomers were grafted onto the surface of Au resonators through ATRP method.Atomic force microscopy?AFM?was adopted to confirm that these acryloyl phenylboronic acid monomers had been successfully grafted onto the surface of Au resonators.Subsequently,QCM-D adsorption experiment implied that these films were able to absorb three kinds of monosaccharide.The fructose showed the largest adsorptionquantity,followed the glucose and galactose.The films which being composed of the monomers with the thiourea units,e.g.3-?acryloylthioureido?phenylboronic acid and 4-?acryloylthioureido?phenylboronic acid,showed the better adsorbent ability for monosaccharide than that without thiourea units,e.g.3-acrylamidophenylboronic acid and 4-acrylamidophenylboronic acid.A possible explain lies that the thiourea units can cooperate with the PBA units and participate in the sugar recognition process through H-bonding interactions.Thefree-standingFe₃O₄@PVP/PNIPAMthermoresponsiveand sugar-responsive photonic crystals hydrogel films were fabricated by the catalytic in situ polymerization reaction by adopting PNIPAM,acryloylphenylboronic acid and monodisperse superparamagnetic Fe₃O₄@PVPCNC particles which was synthesized by solvothermal method.The results of thermoresponsivemeasurement indicated thatthe content of functional monomer in these photonic crystals hydrogels had even no influence to the thermoresponsive performance when their percentage is low.And with the increase of thispercentage,the stereo-hindrance effect of these functional groups would reduce the flexibility of polymer chain,which would cause the decreasing of tunable bandgap range.The results of sugar-responsivemeasurement indicated that the content of functional monomer in these photonic crystals hydrogels had a slightly shift when their percentage is low while it was transferred to the sugar solution.And with the increase of thispercentage,as thesugar solution swells the hydrogel film,the diffraction redshifts owing to the increased osmotic pressure.Otherwise it showed a different blueshifts in the glucose solution which means the hydrogel film was shrinked.The photonic crystals hydrogel contain various monomers also displayed a different performance,the Poly?PNI-co-3-ATPBA?photonic crystals hydrogel which contain the thiourea units showed the largest deviation in the sugar solution.