I have to have a layer (shapefile) with a polygon that has a 100-m buffer zone around each polygon of my original file. With the QGIS Buffer (fixed distance) tool, I get polygons that include the original polygon. But I only want the outside for each polygon.
If the buffer for polygon A intersects the buffer for polygon B, I don't want to lose that part of the "outside" buffer (so I can't use the différenciation symétrique tool (sorry, I'm on a French version of software and I don't know it's equivalent in English). Alternative would be a smart intersection that is polygon-to-polygon based on an ID to get rid of the inner part.

My original datafile is the green and the buffers are underneath in blue.   Just the buffer layer that I tried in blue.

I'm also open to R solutions.

I have to have a layer (shapefile) with a polygon that has a 100-m buffer zone around each polygon of my original file. With the QGIS Buffer (fixed distance) tool, I get polygons that include the original polygon. But I only want the outside for each polygon.
If the buffer for polygon A intersects the buffer for polygon B, I don't want to lose that part of the "outside" buffer (so I can't use the différenciation symétrique tool (sorry, I'm on a French version of software and I don't know it's equivalent in English). Alternative would be a smart intersection that is polygon-to-polygon based on an ID to get rid of the inner part.

My original datafile is the green and the buffers are underneath in blue. 

Just the buffer layer that I tried in blue.