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Abstract: Thermosensitive copolymers poly(NIPAm-co-NNPAm) of N-isopropylacrylamide (NIPAm) with N-n-propylacrylamide (NNPAm) were synthesized by free radical copolymerization using potassium persulfate (KPS) and sodium sulfite (Na2SO3) as initiator. FTIR and 1H NMR confirmed the structure of the copolymer poly(NIPAm-co-NNPAm). The dynamic mechanical analysis and dynamic contact angle were determined. The lower critical solution temperature (LCST) of copolymers was investigated by DSC. The results indicated the LCST decreased with the higher NNPAm contents. The phase transition of the copolymer solution occurred at body temperature within 30s and the copolymers changed into soft solids. The copolymer could be used as a new nonadhesive liquid embolism material for the intervenient therapy of the cerebral arterio-venous malformation (AVM). [Copyright &y& Elsevier]

Poly(N-isopropylacrylamide) (PNIPAAm) was grafted to methylcellulose (MC) with various feeding ratios using ammonium persulfate and N,N,N′,N′-tetramethyl ethylene diamine as an initiator. FTIR results confirm the formation of PNIPAAm-g-MC copolymers. The temperature responsiveness of copolymer gels was investigated by turbidimetry, dynamic contact angle (DCA), differential scanning calorimetry and dynamic mechanical analysis (DMA). The results indicate that PNIPAAm-g-MC hydrogels are strongly temperature responsive. At lower contents of MC, the lower critical solution temperature (LCST) is decreased, whereas further increasing MC contents raises the LCSTs. It is observed that the phase transition of the hydrogels occurs reversibly within 1 min, and near body temperature, a rigid gel can be generated in a certain range of MC content. What is more, the incorporation of MC prevents the syneresis of copolymer hydrogel. DMA measurement reveals that the storage moduli (E′) of the gels increase upon increasing MC contents, and moreover the values of E′ go up markedly above LCST. The copolymer hydrogels hold a promise as a blood vessel barrier by tuning gelation temperature, gelation time and mechanical strength. [Copyright &y& Elsevier]