Nanophase‐separated poly(2‐hydroxyethyl methacrylate)‐l‐polyisobutylene (PHEMA‐l‐PIB) amphiphilic conetworks were obtained by crosslinking α,ω‐bismethacrylate‐terminated polyisobutylene (PIB) via copolymerization with silylated 2‐hydroxyethyl methacylate, followed by the hydrolysis of the silylether groups. Morphology development of a sample containing 64% PIB was monitored by means of transmission electron microscopy (TEM), atomic force microscopy (AFM), and small‐angle X‐ray scattering. For comparison, the morphology of a sample containing 53% PIB was investigated by AFM. The dry conetworks exhibited hydrophilic and hydrophobic phases with average 8–10‐nm domain sizes and were swellable in water as well as in heptane. Swelling amphiphilic conetworks with aqueous cadmium–chloride solution followed by exposure to H2S resulted in nanosized CdS clusters located in the amphiphilic conetworks, that is, for the first time, new inorganic–organic hybrid materials composed of CdS semiconducting nanocrystals and PHEMA‐l‐PIB amphiphilic conetworks were prepared. © 2001 John Wiley & Sons, Inc. J Polym Sci B Part B: Polym Phys 39: 1429–1436, 2001
Covalently surface-attached coatings and free-standing membranes of some 20 µm in thickness were prepared by photocopolymerization of a bitelechelic methacrylate-terminated poly-(dimethylsiloxane) (PDMS) and silyl-protected 2-hydroxyethyl acrylate. After cleaving the silyl groups, the resulting amphiphilic conetworks exhibit two nanoseparated phases in bulk as well as on their surface as shown by atomic force microscopy (AFM). Thereby, the surface structure is controlled by the chemical nature of the surface covering material. Comparing the swelling behavior of 1D swelling of the coatings with the 3D swelling of the membranes revealed perfect interconnectivity of the hydrophilic phase in all compositions prior to and after water treatment. The hydrophobic PDMS phase, on the other hand, is not interconnected in dry state at compositions with less than 80 wt % PDMS. Diffusion experiments indicate that the PDMS phase reorganizes upon swelling and becomes continuous at PDMS contents of about 50 wt % and more.
An isotactic polypropene (i-PP) prepared with a metallocene catalyst system and two random copolymers of propene and ethene with 2.8 and 5.7 wt % ethene, respectively (PP-co-E-2.8, PP-co-E-5.7), were isothermally crystallized during simultaneous small- and wide-angle X-ray scattering (SAXS, WAXS) in synchrotron measurements. Identical measurements were carried out after adding 0.3 wt % N,N‘-dicyclohexyl-2,6-naphthalene dicarboxamide, a β nucleating agent (β-NA). All samples form the γ-modification to a certain extent. WAXS data show that the α-modification is predominant in i-PP, PP-co-E-2.8, and PP-co-E-5.7 isothermally crystallized without β-NA at temperatures below 125 °C. Adding β-NA leads to significant amounts of the β-modification at all crystallization temperatures in all three samples. Thus, the three modifications can be tailored by the crystallization regime of the nucleated samples. The simultaneous occurrence of the three modifications has also implications on the SAXS data. The formation of the γ-modification in addition to the α-modification does not lead to a one-dimensional correlation function K(z) with two distinct long periods or lamella thicknesses. In contrast, the formation of the β-modification results in a long period which can be distinguished from that of the other modifications after generating K(z).
Amphiphilic conetworks (APCN) are new materials composed of covalently bonded otherwise immiscible hydrophilic and hydrophobic polymer chains. The amphiphilic nature of these new crosslinked polymers is indicated by their swelling ability in both hydrophilic and hydrophobic solvents. Special synthetic techniques have been developed for the preparation of these new unique materials, such as poly(2‐hydroxyethyl methacrylate)‐l‐polyisobutylene (PHEMA‐l‐PIB), poly(methacrylic acid)‐l‐polyisobutylene (PMAA‐l‐PIB) and poly(N,N‐dimethylaminoethyl methacrylate)‐l‐polyisobutylene (PDMAEMA‐l‐PIB) (‐l‐ stands for linked by). Due to their unique architecture, macrophase separation of the immiscible components is prevented by the chemical bonding in the conetworks. As a results, phase separation leads to nanodomains with usually 2‐20 nm domain sizes as shown by AFM measurements. The nanophase separated morphology may also lead to smart temperature responsive gels with high mechanical stability, such as in the case of poly(N,N‐dimethylaminoethyl methacrylate)‐l‐polyisobutylene APCNs as discovered during these studies. In another approach, poly(2‐hydroxyethyl methacrylate)‐l‐polyisobutylene and poly(methacrylic acid)‐l‐polyisobutylene APCNs were prepared by a special two‐step process. The new PMAA‐l‐PIB polyelectrolyte APCNs possess smart (intelligent) reversible pH‐responsive properties in aqueous media. These unique conetwork structures and properties of these new emerging materials may lead to numerous new potential applications, such as smart materialk products, sustained drug release matrices, biomaterials, nanohybrids, nanotemplates etc.
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