Adding vertical divider to material-ui AppBar component
You can use a right border in order to add a vertical divider. Use em for the border size and padding size so that your elements are responsive. You can see the result here
<Toolbar>
<Typography
type="title"
color="inherit"
style={{ borderRight: '0.1em solid black', padding: '0.5em' }}
>
Title
</Typography>
<Typography type="title" color="inherit" style={{ padding: '0.5em' }}>
Title 2
</Typography>
</Toolbar>
This can also be used for vertical menubar dividers:
<Divider orientation="vertical" flexItem />
See here: https://material-ui.com/components/dividers/