How to disable a input in angular2

In ts is_edit = true to disable...

<input [disabled]="is_edit=='false' ? true : null" id="name" type="text" [(ngModel)]="model.name" formControlName="name" class="form-control" minlength="2">

I just simply want to disable a input based on true or false.

I tried following:

[disabled]="is_edit=='false' ? true : null"
[disabled]="is_edit=='true'"
[disabled]="is_edit"