3.2　Polymer Characterization

The surface morphologies of the nonimprinted polymer and cordycepin-molecularly imprinted polymer were characterized by scanning electron microscopy.As shown in Figure 3(a)and(b)，the surface of nonimprinted polymer was smooth and homogeneous，whereas the cordycepin-molecularly imprinted polymer was rough and multiporous，probably caused by the removal of the template molecular from the polymer.

Infrared spectra of alpha-methylacrylic acid，glycol dimethyl acrylate，the cordycepin-molecularly imprinted polymer，and the nonimprinted polymer are shown in Figure 3.Glycol dimethyl acrylate had a peak around 1725 cm—1 due to the carbonyl stretching vibration.The adsorption peaks at 1635 cm—1 and 1637 cm—1 were the carbon-carbon double bond stretching vibrations.The hydroxyl groups from alpha-methylacrylic acid and glycol dimethyl acrylate were confirmed by adsorption peaks at 3064 cm—1 and 2931 cm—1.In the cordycepin-molecularly imprinted polymer spectrum，the peak around 1635 cm—1 due to the carbon-carbon double bond decreased significantly，showing that the alphamethylacrylic acid and glycol dimethyl acrylate were highly polymerized.The spectrum of the nonimprinted polymer showed a strong absorption peak at 1730 cm—1，which indicated that the carboxyl group was not involved in the chemical reaction between the functional monomer and cross-linking agent，and the carbonyl groups and methyl group were preserved in the cordycepin-molecularly imprinted polymer.(https://www.daowen.com)

Figure 3　Scanning electron micrographs of(a)the nonimprinted polymer and(b)the cordycepin molecularly imprinted polymer