  Effect of microstructures and interactions on segmental dynamics in
polyethylene glycol (PEG) solution in water is probed with macro-scale
oscillatory rheology and micro-scale diffusion of a fluorescent probe. PEG
solution fluorescence recovery after photobleaching (FRAP) curves have immobile
fractions which increase with PEG concentration, for PEG volume fraction (c) >
0.2, indicating structuring. PEG solution micro-scale diffusion coefficients
follow Rouse scaling D {\ alpha} c^(-0.54) for c < 0.8, resembling unentangled
neutral polymers in good solvent. Addition of nanoclay bentonite (B) in PEG
matrix slows down probe diffusion 3-7 times, with heterogeneous dynamics. With
addition of carboxymethyl cellulose (CMC) in PEG matrix, probe diffusion is
homogeneous with negligibly small enhancement in diffusion time. The macroscale
storage modulii for PEG, PEG+B, and PEG + CMC solutions scale as viscous
fluid-like, followed by short elastic plateau. Beyond the elastic plateau, the
scaling is a concentration-dependent power law greater than the Rouse scaling
of 0.5 for 0.1<c<0.2 PEG solutions. We identify a time scale {\tau}_b due to
intermolecular interactions in PEG, such that for {\omega}>{\tau}_b^(-1) ,
Rouse scaling is recovered. Addition of CMC to PEG also restores Rouse scaling.
Addition of B gives contributions from both polymer matrix and network of B
particles, leading to departure from pure Rouse behaviour. Static
microstructural studies reveal clay aggregation due to depletion interactions
on increasing the concentration of clay particles in PEG matrix, which leads to
a non-monotonic concentration dependence of storage modulus with c.
