HUBUNGAN DUKUNGAN KELUARGA DENGAN TINGKAT DEPRESI PADA NARAPIDANA NAPZA DI RUTAN KELAS IIB KAJHU ACEH BESAR

Banda Ace

Nanostructured polyamide by reactive blending. 2. Transition from nanovesicles to cucumber-like core-shell nanoobjects

peer reviewedPolyamide 12 (PA 12) has been nanostructured by reactive blending with 20 wt% of a symmetric anhydride end-capped polystyrene-b-polyisoprene (PS-b-PIP-anh) The liposome-like nanovesicles which are originally formed in the polyamide matrix (PA 12) are converted into cucumber-like core-shell nanoobjects upon increasing the volume fraction of PS by addi-j tion of homo PS of a molecular weight lower than the PS block. The key effect of the molecular weight of homoPS with respect to the PS bloc,k has been emphasized. The same nanoobjects can be prepared by direct blending of PA12 with 20 wt% of an asymmetric reactive PS-b-PIP-anh diblock with the same molecular weight and a higher PS content compared to the symmetric diblock. The interesting point is that the thickness of the rubbery envelope of the core-shell nanoobjects changes with the method used for their preparation at constant PA12/ PS/PIP composition, as result of a change in the molecular weight of the shell forming block

Nanostructured polyamide by reactive blending. 1. Effect of the reactive diblock composition

Reactive blending of phthalic anhydride end-capped polystyrene-b-polyisoprene diblock (PS-b-PIP-anh) with 80 wt % of polyamide 12 (PA12) results in the very rapid formation of a PS-b-PIP-b-PA triblock copolymer, which self-assembles with formation of characteristic nanoobjects, within the polyamide matrix. For instance, a vesicular nanostructure is formed in the particular case of a symmetric, lamellar-forming diblock copolymer. This morphology actually complies with the lower curvature possible for ABC lamellae diluted in a continuous C phase under shear. In contrast, when the diblock composition is typically asymmetric (at constant molecular weight), vesicles disappear in favor of a core-shell morphology with a cucumber-like suborganization. This spontaneous nanostructuration of the PA12 matrix is quite general. Indeed substitution of an amorphous primary amine end-capped styrene/acrylonitrile random copolymer (SAN-NH2) for PA12 results in exactly the same phase morphology upon reactive blending with PS-b-PIP-anh

Nanostructured PMMA: from lamellar sheets to double-layered vesicles

PMMA was nanostructured by similar to100 nm liposome-like vesicular objects by melt blending with 20 wt % of a symmetric poly(styrene)-b-poly(isoprene)-b-poly(methyl methacrylate) (PS-b-PIP-b-PMMA) triblock copolymer in the dry-brush regime. Whenever the blend was prepared by casting toluene solution, thus under zero-shear conditions, a continuous network of lamellar copolymer sheets was formed in PMMA, which however underwent a transition to the aforementioned vesicles upon application of large amplitude oscillatory shear

Probing of the reaction progress at a PMMA/PS interface by using anthracene-labeled reactive PS chains

The progress of the interfacial reaction of polystyrene chains end-capped by a primary amine (PS-NH2) and PMMA chains end-capped by an anhydride (PMMA-anh) has been monitored by SEC-UV, by using anthracene-labeled polystyrene chains (anth-PS-NH2) as a probe. Assemblies of an anth-PS-NH2 layer and a PMMA-anh layer were annealed at 200 degreesC for various periods of time. The interfacial reaction rate depends on the molecular weight (MW) of the reactive precursors in relation to the gammaN value of the chains. For chains of low gammaN (chiN = 6), the reaction is faster because the interface becomes more diffuse with time, as observed by TEM and AFM, consistent with compatibilization of the weakly immiscible polymers by the copolymer formed in-situ. For chains of higher molecular weight and chiN (10, instead of 6), the interface is much sharper and the residence time at the interface of the symmetric diblock copolymer of higher molecular weight is also increased, which dramatically restricts the progress of the interfacial reaction under the annealing conditions used in this work

Formation of polyamide 12-polyisoprene core-shell particles in polystyrene by reactive blending

Polyamide 12 (PA12)-polyisoprene (PIP) particles with a thermoplastic core and a rubbery shell have been prepared in a thermoplastic matrix (PS) by reactive blending. For this purpose, an anhydride-end-capped PS-b-PIP diblock (PS-b-PIP-anh) has been reacted with PA12 chains end-capped (50% of them) by a primary amine and dispersed in PS. A PS-b-PIP-PA12 triblock has been formed at the interface between the PS matrix and the dispersed PA12 microdomains. Thus, the phase morphology consists of PA12 core-PIP shell particles dispersed in PS. The nonreacted PA12 with respect to PS-b-PIP-anh dictates the size of the polyamide (core) domains, and the reactive diblock (mainly the molecular weight of the PIP block) imposes the shell thickness and modulates the core size by its capacity to compatibilize PA12 and the thermoplastic matrix