I'm not a propellor designer, but did some work on propellor acoustics in the 80s.
As you've probably found out, the aerodynamics get very problematical as you approach transonic relative Mach no.s.
The work on prop-fans in the eighties led to swept airfoils (largely for noise aswell as aerodynamics) and composite shell with titanium spar construction to help combat the twisting moments.
Hamilton Standard, as I recall, did a lot of research in this area, also Dowty, Boeing et al.
A lot of reports were published, and the RAeS library in London is a good source of information.
Ducted fans offer a way of increasing Mach number and disc loading with fewer problems.