title: How to disable a text area or mat-form-field
body: <p>I am using Angular (4) + Angular Material and Reactive Forms for my Form Field. How can I disable that? I tried to google for things like <strong>disabled="true"</strong> or something like that. May can you show me the right syntax? That must be easy. Thanks!</p>
  
  <p>my example:</p>
  
  <pre><code>&lt;mat-form-field class="xxx-form-full-with"&gt;
      &lt;textarea matInput placeholder="My description" formControlName="xxx"&gt;&lt;/textarea&gt;
  &lt;/mat-form-field&gt;
  </code></pre>