Collider.material

Description

The material used by the collider.

If material is shared by colliders, it will duplicate the material and assign it to the collider.

using UnityEngine;

public class Example : MonoBehaviour
{
    // Expose properties in the inspector for easy adjustment.
    float dynFriction;
    float statFriction;

    Collider coll;

    void Start()
    {
        coll = GetComponent<Collider>();

        coll.material.dynamicFriction = dynFriction;
        coll.material.staticFriction = statFriction;
    }
}