= Solution
A sufficiently phase-separated <block copolymer> can show \b[two <glass transitions>, associated approximately with its two microdomains]. Simultaneous feeding instead tends to distribute the <monomers> along each chain, giving a <statistical copolymer> and usually one composition-dependent <glass transition>. Different <monomer> reactivities could produce a gradient rather than a perfectly random sequence.
For a homogeneous mixture an approximate interpolation is the <Fox equation>, $T_g^{-1}=w_1/T_{g1}+w_2/T_{g2}$, with temperatures in kelvin. Two transitions are not guaranteed merely by block architecture: short blocks, miscibility or insufficient experimental resolution can give one broad transition. The contrast is between domain-specific segmental environments and a more uniform mixed environment.
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