We report a lower critical solution temperature (LCST) behavior of binary systems consisting of poly(benzyl methacrylate) (PBnMA) and solvate ionic liquids: equimolar mixtures of triglyme (G3) or tetraglyme (G4) and lithium bis(trifluoromethanesulfonyl)amide. We evaluated the critical temperatures (Tcs) using transmittance measurements. The stability of the glyme-Li+ complex ([Li(G3 or G4)]+) in the presence of PBnMA was confirmed using Raman spectroscopy, pulsed-field gradient spin-echo NMR (PGSE-NMR), and thermogravimetric analysis to demonstrate that the complex was not disrupted. The interaction between glyme-Li+ complex and PBnMA was investigated via 7Li NMR chemical shifts. Upfield shifts originating from the ring-current effect of the aromatic ring within PBnMA were observed with the addition of PBnMA, indicating localization of the glyme-Li+ complex above and below the benzyl group of PBnMA, which may be a reason for negative mixing entropy, a key requirement of the LCST.