Creating Materials at runtime
http://forum.unity3d.com/threads/create-materials-at-runtime.72952/

//通过Shader.Find()创建材质

floor.renderer.material = new Material (Shader.Find(" Diffuse"));

//设置材质参数

floor.renderer.material.SetTextureScale("Tiling", new Vector2(,));

floor.renderer.material.mainTexture = Resources.Load("Floor") as Texture2D;

Shader.Find()
http://docs.unity3d.com/ScriptReference/Shader.Find.html

Shader.Find()

需要注意的问题是，如果Shader是自己写的，则必须放置在Resources下面，否则在Android/iOS环境下，则会出现找不到Shader的问题。

When building a player, a shader will only be included if it is assigned to a material that is used in any scene or if the shader is placed in a "Resources" folder.

We should put the custom shaders into the 'Resources/Shaders/' folder, otherwise, when we built an android apk, shit happens.