dialog.component.html

<h1 matDialogTitle>Withdraw</h1>
<form [formGroup]="form">
  <div mat-dialog-content>
    <mat-form-field>
      <input matInput placeholder="Remark" [formControl]="form.controls['remark']" required>
      <mat-error *ngIf="form.controls['remark'].hasError('required') && form.controls['remark'].touched"
        class="mat-text-warn">You must include remark.</mat-error>
    </mat-form-field>
  </div>
  <br>
  <div mat-dialog-actions>
    <button type="button" mat-raised-button color="primary" [disabled]="!form.valid">Submit{{ btn_name}}</button>
    &nbsp;
    <span fxFlex></span>
    <button mat-raised-button color="accent" (click)="dialogRef.close(false)">No Thanks!</button>
  </div>
</form>