EFFECT OF MOLECULAR WEIGHT OF PEO ON THE STRUCTURE AND PROPERTIES OF PDMAEMA/PEO HYDROGELS

A new kind of binary hydrogels composed of poly(dimethylaminoethylmethacrylate) (PDMAEMA) and poly(ethylene oxide) (PEO) with varying weight average molecular weights ((M)w = 5 × 104, 1 × 105 and 2.5 × 106) were prepared by y-irradiation technology. The properties of PDMAEMA/PEO hydrogels obtained were evaluated in terms of gel fraction, gel strength, thermal characterization and swelling behavior. The gel strength and swelling degree of the hydrogels could be improved obviously after adding PEO into the PDMAEMA system, while the degree of improvement decreased with increasing (M)w of PEO. The temperature sensitivity of PDMAEMA/PEO was retained only in the sample with PEO of (M)w = 5 × 104, and the pH sensitivity was retained in samples with PEO of (M)w = 5 × 104 and 1 × 105. When DMAEMA/PEO mixtures containing PEO of (M)w = 5 × 104 were irradiated, the main reaction could be the cross-linking of DMAEMA, and the linear PEO molecular chains could penetrate into the cross-linked network of PDMAEMA. With increasing Mw of PEO, some side reactions were induced, such as grafting of DMAEMA onto PEO molecules, the scission or cross-linking of PEO.

Effect of Molecular Weight of Peo on the Structure and Properties of Pdmaema/Peo Hydrogels

 A new kind of binary hydrogels composed of poly(dimethylaminoethylmethacrylate) (PDMAEMA) and poly(ethylene oxide) (PEO) with varying weight average molecular weights ( = 5 ? 104, 1 ? 105 and 2.5 ? 106) were prepared by γ-irradiation technology. The properties of PDMAEMA/PEO hydrogels obtained were evaluated in terms of gel fraction, gel strength, thermal characterization and swelling behavior. The gel strength and swelling degree of the hydrogels could be improved obviously after adding PEO into the PDMAEMA system, while the degree of improvement decreased with increasing of PEO. The temperature sensitivity of PDMAEMA/PEO was retained only in the sample with PEO of = 5 ? 104, and the pH sensitivity was retained in samples with PEO of = 5 ? 104 and 1 ? 105. When DMAEMA/PEO mixtures containing PEO of = 5 ? 104 were irradiated, the main reaction could be the cross-linking of DMAEMA, and the linear PEO molecular chains could penetrate into the cross-linked network of PDMAEMA. With increasing of PEO, some side reactions were induced, such as grafting of DMAEMA onto PEO molecules, the scission or cross-linking of PEO.