Yes, I have recently done exactly what you are trying to do. You simply need to declare a template variable #picker
and bind the button click event to picker.open()
<button ion-button icon-right (click)="picker.open()">
<ion-datetime #picker pickerFormat="DD MMMM YYYY" [min]="datePickerMin" [(ngModel)]="datePicker" (ionChange)="changeDate()"></ion-datetime>
<ion-icon name="calendar"></ion-icon>
</button>