ABSTRACT
In this study, the stereocomplexation between a novel stereospecific cyclic vinyl polymer, that is, cyclic syndiotactic poly(methyl methacrylate) (st-PMMA), with the complementary linear isotactic (it-) PMMA was investigated. Surprising new insight into the effects of the topology (i.e., end groups), size, and tacticity of the assembling components on stereocomplex formation was obtained. Characterization of the stereocomplexes revealed that the self-assembly of cyclic st-PMMAs and linear it-PMMAs resulted in the formation of an unprecedented "polypseudorotaxane-type" supramolecular assembly. This stereocomplex exhibited remarkably different physical properties as compared to the conventional PMMA triple-helix stereocomplex as a result of the restricted topology imposed by the cyclic st-PMMA assembling component.
Subject(s)
Azides/chemistry , Polycyclic Compounds/chemistry , Polymethyl Methacrylate/chemistry , Azides/chemical synthesis , Click Chemistry , Cyclization , Models, Molecular , Molecular Structure , Polycyclic Compounds/chemical synthesis , Polymethyl Methacrylate/chemical synthesis , StereoisomerismABSTRACT
Bromoisobutyramide (BrIBAM)-modified silica templates facilitate the formation of bio-functional thin films made of a range of biopolymers (e.g., polypeptides, nucleic acids or polysaccharides). Upon template removal, non-covalent free-standing biopolymeric assemblies (e.g., hollow capsules or replicated spheres and fibers) are formed without the need for covalent cross-linking.
Subject(s)
Amides/chemistry , Biomimetics/methods , Biopolymers/chemistry , Hydrocarbons, Brominated/chemistry , Biopolymers/classification , Cross-Linking Reagents/chemistry , Flow Cytometry , Microscopy, Electron, Scanning , Microscopy, Fluorescence , Microspheres , Propylamines , Silanes/chemistry , Silicon Dioxide/chemistryABSTRACT
The continuous assembly of polymers (CAP) via atom transfer radical polymerisation (ATRP) is reported as an efficient approach for the preparation of dense, cross-linked, nanoscale engineered films as surface coatings, hollow capsules and replica particles. These films can be reinitiated to allow the preparation of thicker films without loss of film growth efficiency while maintaining similar film density.
Subject(s)
Nanostructures/chemistry , Nanotechnology/methods , Polymerization , Polymers/chemistry , Free Radicals/chemistry , Silicon Dioxide/chemistryABSTRACT
The efficient formation of low polydispersity core cross-linked star (CCS) polymers via controlled/living radical polymerization (LRP) and the arm-first approach was found to be dependent on the mediating catalyst system. The Ru catalyst, Ru(Ind)Cl(PPh3)2 Cat. 1, and tertiary amine co-catalyst were used to synthesize highly living poly(methyl methacrylate) (PMMA) macroinitiators, which were then linked together with ethylene glycol dimethacrylate (EGDMA) to form PMMA(arm)PEGDMA(core) CCS polymers. The quantitative and near-quantitative synthesis of CCS polymers were observed for low to moderate molecular weight macroinitiators (M(n) = 8 and 20 kDa), respectively. Lower conversions were observed for high-molecular weight macroinitiators (M(n) ≥ 60 kDa). Overall, an improvement of between 10 and 20% was observed when comparing the Cat. 1 system to a conventional Cu-catalyzed system. This significant improvement in macroinitiator-to-star conversion is explained in the context of catalyst system selection and CCS polymer formation.
Subject(s)
Methacrylates/chemistry , Polyethylene Glycols/chemistry , Polymers/chemistry , Polymethyl Methacrylate/chemistry , Catalysis , Gels/chemistry , Molecular Structure , Molecular Weight , Polymerization , Polymers/chemical synthesisABSTRACT
This communication details the successful synthesis of low polydispersity core cross-linked star (CCS) polymers via DPE-mediated polymerisation. We demonstrate the ability to produce poly(methyl methacrylate) and poly(acrylonitrile) CCS polymers that are currently inaccessible via the two most common non-metal-based controlled radical polymerisation techniques (NMP and RAFT polymerisations).