[Study on thermo-sensitive intelligent targeting type drug carriers (I) porous membranes with grafted thermo-sensitive gates].

Thermo-responsive intelligent membranes with linear grafted poly(N-isopropylacrylamide) (PNIPAM) gates on the inner pore surface were prepared, and experiments were carried out on the thermo-responsive gating characteristics. Plasma-graft pore-filling polymerization was used to graft PNIPAM into the pore of the porous flat membranes. The experimental results showed that PNIPAM-grafted PVDF (PNIPAM-g-PVDF) membranes were featured with thermo-responsiveness due to the thermo-responsive swollen-shrunken property of PNIPAM chains grafted on the inner pore surface of the membrane. At temperatures below the lower critical solution temperature (LCST), the linear grafted PNIPAM chains on the inner pore surface were in the swollen state, and the pores in the membrane were closed; in contrast, the grafted PNIPAM chains were in the shrunken state at temperatures above the LCST, and therefore the pores in the membrane were open. The LCST of the thermo-sensitive gates could be adjusted by adding acrylamide (AAM) in the N-isopropylacrylamide (NIPAM) monomer solution, the LCST of the poly(NIPAM-co-AAM) gates increased simply with the increase of the AAM fraction.