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Polyethylene-block-syndiotactic polypropylene (PE-block-sPP) crystalline-crystalline block copolymers with different block lengths have been synthesized with a stereospecific living organometallic catalyst. Samples of PE-block-sPP have been epitaxially crystallized onto crystals of p-terphenyl (3Ph) to achieve a control over the crystallization of both blocks and study the dependence of the thin film morphology on the sequential crystallization of the two blocks by cooling from the melt. The epitaxial crystallization generates oriented overgrowth of both crystals of sPP and PE, with a highly ordered single orientation of sPP lamellae and a double orientation of PE lamellae onto the (001) face of 3Ph. The final morphology depends on which polymer block crystallizes first, a sequence that depends on the block copolymer composition and block lengths. Ordered nanostructures with alternating lamellar domains are obtained and oriented by the lamellae that crystallize first. [ABSTRACT FROM AUTHOR]

A set of syndiotactic polypropylenesamples with tailored degreeof stereoregularity and uniform distribution of stereodefects, obtainedvia organometallic catalysis, was used to study the relation betweenthe syndiotactic pentad concentration and the viscoelastic plateaumodulus in the melt state. The plateau modulus was found to increasewith increasing the degree of stereoregularity, indicating that syndiotacticpolypropylenes of different stereoregularity produce a different entanglementdensity of the amorphous phase. The change in plateau modulus washighly nonlinear for large values of syndiotactic pentad contents,suggesting that the presence of even a relatively small number ofdefects along the syndiotactic backbone significantly alters the spacefilling attitude of the polymer chain in the melt. This result, whichconfirms and extends those already obtained from experiments and numericalsimulations, points out to the concept that the dynamics of macromolecularchains is largely controlled by the relative configuration of consecutivestereoisomeric centers along the chain, thus providing a link betweenchain dynamics and molecular architecture. [ABSTRACT FROM AUTHOR]

Magnetoresistive (MR) biosensors combine distinctive features such as small size, low cost, good sensitivity, and propensity to be arrayed to perform multiplexed analysis. Magnetic nanoparticles (MNPs) are the ideal target for this platform, especially if modified not only to overcome their intrinsic tendency to aggregate and lack of stability but also to realize an interacting surface suitable for biofunctionalization without strongly losing their magnetic response. Here, we describe an MR biosensor in which commercial MNP clusters were coated with gold nanoparticles (AuNPs) and used to detect human IgG in water using an MR biochip that comprises six sensing regions, each one containing five U-shaped spin valve sensors. The isolated AuNPs (satellites) were stuck onto an aggregate of individual iron oxide crystals (core) so that the resulting core@satellite magnetic particles (CSMPs) could be functionalized by the photochemical immobilization technique-an easy procedure that leads to oriented antibodies immobilized upright onto gold. The morphological, optical, hydrodynamic, magnetic, and surface charge properties of CSMPs were compared with those exhibited by the commercial MNP clusters showing that the proposed coating procedure endows the MNP clusters with stability and ductility without being detrimental to magnetic properties. Eventually, the high-performance MR biosensor allowed us to detect human IgG in water with a detection limit of 13 pM (2 ng mL -1 ). Given its portability, the biosensor described in this paper lends itself to a point-of-care device; moreover, the features of the MR biochip also make it suitable for multiplexed analysis., Competing Interests: The authors declare no competing financial interest., (© 2022 The Authors. Published by American Chemical Society.)

Highly ordered lamellar nanostructures with high orientation of lamellar microdomains have been obtained by epitaxial crystallization of crystalline diblock copolymers constituted by crystalline polyethylene (PE) linked to an amorphous block of a propene-ethene random copolymer (EP). The epitaxial crystallization onto crystals of p-chlorobenzoic acid induces formation of crystalline PE lamellae highly aligned along one direction, resulting in ordered lamellar nanostructures with perfectly aligned layers of crystalline PE alternating to amorphous layers of EP block. The periodicity of the lamellar structure can be modulated by modifying the molecular mass of the amorphous EP block. Epitaxy has been coupled with the technique of gold decoration so that the ordered nanostructures produced by epitaxy act as template for the formation of long, straight, and parallel rows of gold nanoparticles.

We set up a facile approach for fabrication of supports with tailored nanoporosity for immobilization of enzymes. To this aim block copolymers (BCPs) self-assembly has been used to prepare nanostructured thin films with well-defined architecture containing pores of tailorable size delimited by walls with tailorable degree of hydrophilicity. In particular, we employed a mixture of polystyrene-block-poly(l-lactide) (PS-PLLA) and polystyrene-block-poly(ethylene oxide) (PS-PEO) diblock copolymers to generate thin films with a lamellar morphology consisting of PS lamellar domains alternating with mixed PEO/PLLA blocks lamellar domains. Selective basic hydrolysis of the PLLA blocks generates thin films, patterned with nanometric channels containing hydrophilic PEO chains pending from PS walls. The shape and size of the channels and the degree of hydrophilicity of the pores depend on the relative length of the blocks, the molecular mass of the BCPs, and the composition of the mixture. The strength of our approach is demonstrated in the case of physical adsorption of the hemoprotein peroxidase from horseradish (HRP) using 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) with H 2 O 2 as substrate. The large surface area, the tailored pore sizes, and the functionalization with hydrophilic PEO blocks make the designed nanostructured materials suitable supports for the nanoconfinement of HRP biomolecules endowed with high catalytic performance, no mass-transfer limitations, and long-term stability.

The structure and crystallization properties of a norbornene end-functionalized syndiotactic polypropylene (sPP) macromonomer (MMsPP) with [rrrr] = 80 mol % and molecular mass Mn = 3600 g/mol and corresponding comb-like poly(macromonomer) (pMMsPP) with Mn = 100000 g/mol have been investigated using wide angle (WAXS) and small angle (SAXS) X-ray scattering, atomic force (AFM), transmission electron (TEM), and optical (OM) microscopy. The analysis reveals the tendency of the macromonomer and poly(macromonomer) to form structures characterized by layers of sPP chains alternated to layers occupied by the cyclic groups (norbornene or polynorbornene), and a small degree of interdigitation of sPP chains belonging to adjacent layers facing each other in an end-to-end arrangement. It is argued that this layering is dictated, upon crystallization, by nanophase separation of the flexible sPP chains in regions apart from those occupied by the cyclic groups coupled to formation of sPP crystals organized in the lamellar morphology. SAXS measurements indicate that in isothermally crystallized samples the layered structures are irregular and include sPP lamellar crystals of uniform thickness separated by amorphous layers whose thickness values have a multimodal distribution. These properties are intrinsic to the chemical structure of our systems and are only minimally influenced by the topological constrains of the covalent bonding of macromonomers in the corresponding comb-polymer.