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A series of novel hybrid poly(acetoxylstyrene-co-isobutylstyryl-POSS)s (PAS−POSS) and poly(vinylpyrrolidone-co-isobutylstyryl-POSS)s (PVP−POSS) are synthesized and characterized. The POSS content in these hybrids can be controlled by varying the monomer feed ratio. The polyhedral oligosilsesquoixane (POSS) moiety can effectively increase the T g of the resultant organic/inorganic hybrid polymer at a relatively high POSS content and produce the hybrid copolymer with narrower molecular weight distribution. The FTIR spectra are used to investigate the structure−property relationship of these hybrid polymers, and the T g enhancement mechanism is discussed in detail.

We have investigated the phase behavior of poly(4-vinylphenol-b-styrene) (PVPh-b-PS) when respectively blended with poly(4-vinylpyridine) (P4VP), poly(methyl methacrylate) (PMMA), and PVPh homopolymers by mediated hydrogen bonding strengths with the PVPh block of the copolymer. The Fourier transform infrared spectroscopic result indicates that the PVPh-b-PS/P4VP blend has a much higher fraction ( f H ) of hydrogen-bonded PVPh blocks for a significantly higher miscibility compared with the blends with PMMA and PVPh homopolymers. Consequently, the PVPh-b-PS/P4VP blend, behaving as a neat diblock copolymer, exhibited a series of order-order phase transitions from the lamellar, gyroid, hexagonally packed cylinder to body-centered cubic structures when the P4VP content increases from 6 to 71% (volume fraction), as evidenced consistently by transmission electron microscopy and small-angle X-ray scattering. In contrast, both the PVPh-b-PS/PMMA and PVPh-b-PS/PVPh blends maintained essentially the lamellar structure upon a similar volume fraction increase in the homopolymers; the lamellar structure, however, was distorted to different extents at higher volume fractions of the additives, depending on the hydrogen bonding strength. On the basis of the results, the ratio of interassociation equilibrium constant (K A ) over self-association equilibrium constant (K B ), K A /K B , is introduced as a convenient guide in estimating the phase behavior of similar polymer blends featuring hydrogen bonding interactions between the homopolymer additive and copolymer: with a K A /K B ratio much larger than unity, the blend system tends to behave as a neat copolymer; with a K A /K B ratio significantly smaller than unity, phase separation instead of order-order phase transitions can be expected for the blend above certain volume fraction of homopolymer additive.

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