Blend to other Material on Trigger Event

heyho when i press on my gameobject i want that his current material blend in one other material and back after you pressed again pls help i tried this but it wont work some ideas ?

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class materialchanger : MonoBehaviour {

		public Material material1;
		public Material material2;
		public float duration = 2.0F;
		public Renderer rend;
		void Start() {
			rend = GetComponent<Renderer>();
			rend.material = material1;
		}
		public void clickblendshphere() {
			float lerp = Mathf.PingPong(Time.time, duration) / duration;
			rend.material.Lerp(material1, material2, lerp);
		}
	}

no ideas?