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A new kind of binary hydrogels composed of poly（dimethylaminoethylmethacrylate）（PDMAEMA）and poly（ethylene oxide）（PEO）with varying weight average molecular weights（（?）

w

=5×10

4

1×10

5

and 2.5×10

6

）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 （?）

w

of PEO.The temperature sensitivity of PDMAEMA/PEO was retained only in the sample with PEO of （?）

w

=5×10

4

and the pH sensitivity was retained in samples with PEO of （?）

w

=5×10

4

and 1×10

5

.When DMAEMA/PEO mixtures containing PEO of （?）

w

=5×10

4

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 （?）

w

of PEO

some side reactions were induced

such as grafting of DMAEMA onto PEO molecules

the scission or cross-linking of PEO.