Macroporous temperature-sensitive poly(N-isopropylacrylamide) (PNIPAAm) hydrogels have been successfully synthesized by using poly(ethylene glycol) (PEG) as the pore-forming agent. Scanning electron microscope graphs reveal that the macroporous network structure of the hydrogels can be adjusted by applying different molecular weights of PEG during the polymerization reaction. The surface roughness of the hydrogels is also investigated using atomic force microscopy, and the results indicate that the surface of the PEG-modified gel is much rougher compared to that of the conventional PNIPAAm gel. The newly invented macroporous hydrogels exhibit much better properties as temperature-sensitive intelligent polymers. For instance, at a temperature below the lower critical solution temperature (LCST), they absorb larger amounts of water and show obviously higher equilibrated swelling ratios in the aqueous medium. Particularly, due to their unique macroporous structure, the PEG-modified hydrogels show a tremendously faster response to the external temperature changes during deswelling and reswelling processes as the temperature cycles across the LCST. They can also shrink and lose water with dramatically rapid rates at temperatures above the LCST. The macroporous PNIPAAm gel has potential applications in controlled release of macromolecular active agents.

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Novel fluorinated main-chain liquid crystalline/crystalline polymers were prepared through thin film polymerization. Two polymer systems were studied:  one from 2,6-acetoxynaphthoic acid (ANA), acetoxyacetanilide (AAA), and 4,4‘-(hexafluoroisopropylidene)bis(benzoic acid) (6F acid) and the other from ANA, hydroquinone diacetate (HQAT), and 6F acid. The surface energy was estimated using contact angles of water, glycerol, and diiodomethane. A small amount of −C(CF3)2− in the main chain lowered the surface energy, and the fluorocarbons were preferentially enriched at the air−polymer interface, causing low surface energy and large water contact angles. These results agreed with XPS data. Since the −O−Ar−O− unit in the HQAT moiety is more rigid than the −O−Ar−N− unit in the AAA moiety, LC texture formed more easily in the ANA/HQAT/6F acid system than in the ANA/AAA/6F acid system. Contrarily, the fluorocarbons enriched more preferentially at the surface in the ANA/AAA/6F acid system than in the ANA/HQAT/6F acid system. Moreover, the hydrogen bonding originating from the amide group hindered further decrease of surface energy with an increase in 6F acid content in the ANA/AAA/6F acid system.