Version: 2017.1
public ParticleSystem.CollisionModule collision ;


Access the particle system collision module.

Particle system modules do not need to be reassigned back to the system; they are interfaces and not independent objects.

using UnityEngine;
using System.Collections;

public class ExampleClass : MonoBehaviour { void Start() { ParticleSystem ps = GetComponent<ParticleSystem>(); var coll = ps.collision; coll.enabled = true; coll.bounce = 0.5f; } }