Koki Fukaya, Hiroshi Sekiguchi, Ryoko Nakano, Shigeru Yao Dep. Chem. Eng. Fukuoka Univ. A block copolymer composed of a monomer having a long alkane side chain and another monomer having a functionality such as a hydrophobic property becomes a side chain crystalline block copolymer (SCCBC) which crystallizes at the side chain of the former. We had found the SCCBC has an adsorption function to polyethylene surface by crystalline supramolecular interaction strongly. By using the SCCBC, we can modify surface property of PE chemically and easily. Polytetrafluoroethylene (PTFE) is also known as a polymer material with super hydrophobicity and super-soil resistance, and used in many fields. In addition, the porous membrane is well known as a functional material having both super hydrophobicity and water vapor permeability. However, it is expensive and also a material that has problems in process ability and strength. In this time, we had polymerized a new chemical structural and triblock type SCCBC that is composed with a monomer having fluorocarbon side chain as a functional monomer by RAFT living radical polymerization method. We found that this Fluorinated SCCBC (F-SCCBC) has an ability that can modify PE surface to super hydrophobic. We also found that when applied the F-SCCBC to porous membranes, the porous membrane becomes to have both super hydrophobic and water vapor permeability like PTFE membrane.