We have synthesized poly(methyl methacrylate- b-4-vinylpyridine) (PMMA- b-P4VP) and poly(styrene- r-vinylphenol) (PS- r-PVPh) copolymers by using anionic and free radical polymerizations, respectively. Well-defined micelles through hydrogen bonding have been prepared by mixing PMMA- b-P4VP diblock copolymer and PS- r-PVPh random copolymer in a single solvent. Block copolymers were mixed with random copolymers, with various [N]/[OH] ratios (4/1, 2/1, 1/1, and 1/4) in which "[N]/[OH]" represents the molar ratio of pyridine groups on P4VP to hydroxyl groups on PVPh. The presence distribution of PVPh/P4VP and PVPh/PMMA hydrogen bonding depends on the feeding ratio of PVPh to P4VP. When the PVPh content is lower than that of P4VP, hydrogen bonding occurs only between PVPh and P4VP; with excess PVPh, additional hydrogen bonding between PVPh and PMMA would occur. Furthermore, the effect of the solvent quality on the self-assembly behavior of PMMA- b-P4VP/PS- r-PVPh blends is investigated by considering tetrahydrofuran (THF) and dimethylformamide (DMF) as common solvents. We can mediate the strength of hydrogen bonding in blend systems by adopting different solvents and inducing different morphology transitions. 相似文献
The intermolecular interaction between poly(vinylphenol) (PVPh) and polycaprolactone (PCL) and the crystallization behavior of PCL in PCL/PVPh blends with different compositions and under different conditions were investigated by Fourier transform infrared spectra (FTIR) and differential scanning calorimetry (DSC). It has been shown that the PCL in the blends with different blend ratios all exists in crystalline state after solution casting, even though the crystallinity decreases with increasing PVPh content. For the melt crystallized samples, PCL in its 80/20 PCL/PVPh sample can still crystallize. The crystallinity is, however, lower than that of the solution cast sample. For blends containing 50% or 20% PCL, the as-cast samples are semicrystalline and can change to compatible amorphous state after heat treatment process. FTIR analysis shows the existence of hydrogen bonding between PCL and PVPh and the fraction of hydrogen bonds increases remarkably after heat treatment process. 相似文献
We report a new approach toward preparing self-assembled hydrogen-bonded complexes having vesicle and patched spherical structures from two species of block copolymers in nonselective solvents. Two diblock copolymers, poly(styrene-b-vinyl phenol) (PS-b-PVPh) and poly(methyl methacrylate-b-4-vinylpyridine) (PMMA-b-P4VP), were synthesized through anionic polymerization. The assembly of vesicles from the intermolecular complex formed after mixing PS-b-PVPH with PMMA-b-P4VP in THF was driven by strong hydrogen bonding between the complementary binding sites on the PVPH and P4VP blocks. In contrast, well-defined patched spherical micelles formed after blending PS-b-PVPh with PMMA-b-P4VP in DMF: the weaker hydrogen bonds formed between the PVPh and P4VP blocks in DMF, relative to those in THF, resulted in the formation of spherical micelles having compartmentalized coronas consisting of PS and PMMA blocks. 相似文献
The sulfonated poly(ether sulfone) (SPES) was successfully prepared using chlorosulfonic acid as a sulfonating agent. Diglycidylether of bisphenol-A (DGEBA) epoxy resins were modified with different contents of SPES, and the thermal and mechanical interfacial properties of DGEBA/SPES blends were investigated. As a result, the surface free energy of the blends was increased by the addition of SPES. DSC measurements revealed that the curing reaction was delayed with the increase of SPES content. Whereas, the thermal stabilities of the blends were slightly decreased as the SPES content increased. Meanwhile, the glass transition temperature and fracture toughness of the blends were increased with increasing SPES content, due to the improved intermolecular interactions, such as hydrogen bonding, between the hydroxyl group of DGEBA and the sulfonic group of SPES in the blends. The agreement could be observed by SEM which revealed phase separated morphology of DGEBA/SPES blends. 相似文献
Summary: Random copolymers of poly(styrene-co-4-vinylpyridine) (S4VP) and poly (styrene-co-2-hydroxyethyl acrylate) (SHEA) of different compositions were prepared and characterized. An investigation of the effects of solvent and densities of the interacting species incorporated within these copolymers showed that novel and various hydrogen bonding interpolymer complexes of different structures were elaborated when these copolymers are mixed together. The specific interactions that occurred within the SHEA copolymers and the elaborated complexes were evidenced by FTIR qualitatively from the appearance of a new band at 1604 cm−1 and quantitatively using appropriate spectral curve fitting in the carbonyl and pyridine regions. The intermolecular hydrogen bonding interactions that occurred between the hydroxyl groups of the SHEA and the nitrogen atom of the pyridine groups in the S4VP are stronger than the self-associations within the SHEA. In the solid state, a DSC analysis showed that the variation of the glass transition temperatures of these materials with the composition behaved differently with the densities of interacting species and were analyzed quantitatively. A thermal stability study of the synthesized copolymers and of their different mixtures carried by thermogravimetry confirmed a similar behaviour. 相似文献
Epoxy resin (ER)/poly(ethylene oxide) (PEO) and/or poly(e-caprolactone) (PCL) blends cured with 1,3,5-trihydroxybenzene (THB) were prepared via the in situ curing reaction of epoxy monomers in the presence of PEO and/or PCL, which started from the initially homogeneous mixtures of DGEBA, THB and PEO and/or PCL. The miscibility and the intermolecular specific interactions in the thermosetting polymer blends were investigated by means of differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR). The two systems displayed single and composition-dependant glass transition temperatures (T gs), indicating the full miscibility of the thermosetting blends. The experimental T gs of the blends can be well accounted for by Gordon-Taylor and Kwei equations, respectively. The T g-composition behaviors were compared with those of poly(hydroxyether of bisphnol A) (Phenoxy) blends with PEO and PCL. It is noted that the formation of crosslinked structure has quite different effects on miscibility and intermolecular hydrogen bonding interactions for the thermosetting polymer blends. In ER/PEO blends, the strength of the intermolecular hydrogen bonding interactions is weaker than that of the self-association in the control epoxy resin, which is in marked contrast to the case of Phenoxy/PEO blends. This suggests that the crosslinking reduces the intermolecular hydrogen bonding interactions, whereas the intermolecular hydrogen bonding interactions were not significantly reduced by the formation of the crosslinking structure in ER/PCL blends. 相似文献
This paper describes a new approach towards preparing self‐assembled hydrogen‐bonded complexes that have vesicle and patched spherical structures from two species of block copolymer in non‐selective solvents. The assembly of vesicles from the intermolecular complex formed after mixing polystyrene‐block‐poly(4‐vinyl phenol) (PS‐b‐PVPh) with poly(methyl methacrylate)‐block‐poly(4‐vinylpyridine) (PMMA‐b‐P4VP) in tetrahydrofuran (THF) is driven by strong hydrogen bonding between the complementary binding sites on the PVPh and P4VP blocks. In contrast, well‐defined patched spherical micelles form after blending PS‐b‐PVPh with PMMA‐b‐P4VP in N,N‐dimethylformamide (DMF): weaker hydrogen bonds form between the PVPh and P4VP blocks in DMF, relative to those in THF, which results in the formation of spherical micelles that have compartmentalized coronas that consist of PS and PMMA blocks.
Miscibility with a linear Tg–composition relationship was proven for blend of poly(butylene adipate-co-butylene terephthalate) [P(BA-co-BT)] with poly(4-vinyl
phenol) (PVPh). In comparison to the blends of PBA/PVPh and poly(butylene terephthalate) (PBT)/PVPh, the Kwei’s Tg model fitting on data for the P(BA-co-BT)/PVPh blend yields a q value between those for the PBA/PVPh and PBT/PVPh blends. The q values suggest that the interaction strength in the P(BA-co-BT)/PVPh blend is not as strong as that in the PBT/PVPh blend.
Upon mixing the PVPh into the immiscible blend of PBA and PBT, the ternary PBA/PBT/PVPh blends only exhibits partial miscibility.
Full-scale ternary miscibility in whole compositions is not possible owing to the significant ∆χ effect (χij – χik). The wavenumber shifts of the hydroxyl IR absorbance band indicates that the H-bonding strength is in decreasing order—PBT/PVPh
> P(BA-co-BT)/PVPh > PBA/PVPh—and shows that the BA segment in the copolymer tends to defray interactions between P(BA-co-BT)
and PVPh in blends. 相似文献