I had a dream last night 
It's really foolish, this way works!
<md-button ng-disabled="msg.payload.disabled"> {{msg.payload.disabled ? 'disabled': 'enabled'}} </md-button>
also without {{}} > see Angular expressions for more details.
Flow:
[{"id":"4ebdb7bc.0f49d8","type":"ui_template","z":"7c6a9ec3.f1512","group":"5a2c927c.ba1edc","name":"","order":2,"width":0,"height":0,"format":"<md-button ng-disabled=\"msg.payload.disabled\"> {{msg.payload.disabled ? 'disabled': 'enabled'}} </md-button>","storeOutMessages":true,"fwdInMessages":true,"templateScope":"local","x":600,"y":520,"wires":[[]]},{"id":"15210d31.669453","type":"inject","z":"7c6a9ec3.f1512","name":"","topic":"","payload":"{\"disabled\":true}","payloadType":"json","repeat":"","crontab":"","once":false,"onceDelay":0.1,"x":400,"y":480,"wires":[["4ebdb7bc.0f49d8"]]},{"id":"60b1fb0e.6a54f4","type":"inject","z":"7c6a9ec3.f1512","name":"","topic":"","payload":"{\"disabled\":false}","payloadType":"json","repeat":"","crontab":"","once":false,"onceDelay":0.1,"x":400,"y":520,"wires":[["4ebdb7bc.0f49d8"]]},{"id":"5a2c927c.ba1edc","type":"ui_group","z":"","name":"light","tab":"42b914b0.66a0ac","order":null,"disp":true,"width":"6","collapse":false},{"id":"42b914b0.66a0ac","type":"ui_tab","z":"","name":"Main","icon":"dashboard","order":1}]
