Search results for "copolymer"

N-Isopropylacrylamide andN-Isopropylmethacryl-amide: Cloud Points of Mixtures and Copolymers

2001

The cloud point curve of aqueous solutions of poly(N-isopropylacrylamide), poly(N-isopropylmethacrylamide) and their statistical copolymers were determined turbidimetrically. All the Systems demix upon heating at the cloud point temperature and mix reversibly upon cooling. The cloud points are independent of the total concentration of the solutions (dilute range) and of the sample thickness. Mixtures of the homopolymers poly(N-isopropylacrylamide) and poly(N-isopropylmethacrylamide) in water (ternary systems) exhibit two cloud points, which are nearly the same as the cloud points of the two binary systems homopolymer/water. A quantitative correlation was found between the cloud point temper…

Morphology of PEO/PDMS blends during shear: Coexistence of two droplet/matrix structures and additive effects

2005

Abstract The morphologies of blends of polyethyleneoxide (PEO 37) and poly(dimethylsiloxane)s (PDSM), with viscosity ratios, λ , of approximately one (PDMS 230) or 2.8 (PDMS 314, being the component of higher viscosity) and interfacial tensions on the order of 10 mN/m, were investigated at 70 °C as a function of shear rate (up to 10 s −1 ) and of time. For the system PEO 37/PDMS 230 we have also studied the influence of the compatibilizer dimethyl–ethyleneoxide–copolymer (PDMS- co -PEO), which is only reasonably soluble in PEO. To investigate the morphologies we have used an optical shear cell in combination with a light microscope. The most important observation consists in the formation o…

On the use of PET-LCP copolymers as compatibilizers for PET/LCP blends

1996

Copolyesters of poly[ethylene terephthalate) (PET) with a liquid crystalline polymer (LCP), SBH 1:1:2, have been synthesized by the polycondensation, carried out in the melt at temperatures up to 300 degrees C of sebacic acid (S), 4,4'-dihydroxybiphenyl (B), and 4-hydroxybenzoic acid (H) in the presence of PET. The PET-SBH copolyesters have been characterized by differential scanning calorimetry, scanning electron microscopy, X-ray diffraction, etc., and the relationships between properties and preparation conditions are discussed. The copolyesters show a biphasic nature, which is more evident for the products synthesized with a thermal profile comprising relatively lower temperatures (220-…

Soluble Hyperbranched Poly(glycolide) Copolymers

2010

A series of (hyper)branched poly(glycolide) copolymers has been prepared by copolymerization of glycolide (GA) with 2,2-bis(hydroxymethyl)butyric acid (BHB) via combined ROP/AB2-polycondensation. Polymerization was conducted in bulk and catalyzed by stanneous-2-ethyl hexanoate (Sn(Oct)2). The branched topology of the resulting polyesters was studied in detail by 1D- and 2D-NMR spectroscopy and confirmed by the synthesis and characterization of model compounds. The AB2 monomer BHB was incorporated either as a dendritic or focal unit, but hardly in linear or terminal mode. As expected for multifunctional polycondensation, SEC measurements showed polydisperse products with polydispersity index…

Hyperbranched Polylactide Copolymers

2006

A series of hyperbranched poly(l-lactide) (PLLA) copolymers were prepared by copolymerization of dilactide with 2,2-bis(hydroxymethyl)butyric acid (BHB) as an AB2 comonomer via a combined ring-open...

Tuning of the photoinduced charge transfer process in donor-acceptor "double cable" copolymers

2003

The covalent linking of acceptor molecules to electron donating conjugated polymer is an approach for the development of new photoactive materials for the fabrication of organic photoelectric conversion devices. With this strategy we have designed a polyalkylthiophene copolymer series containing in the side chain anthraquinone molecules as electron acceptor. The peculiar features of the copolymers are the good processability and the ease in tailoring the content of acceptor moieties. Their potential use as photoactive materials is investigated in terms of the photoinduced charge transfer properties, studied by FTIR photoinduced absorption and Light Induced Electron Spin Resonance spectrosco…

Shear Modulus of an Irreversible Diblock Copolymer Network from Self-Consistent Field Theory

2019

Using self-consistent field theory, we investigate the stretching-induced microphase separation in an irreversibly cross-linked polymer network composed of diblock copolymer chains and estimate its...

¿Conjugated? Copolymers from a Pechmann Dye Derivative

2016

Conducting Polymer with Orthogonal Catechol and Disulfide Anchor Groups for the Assembly of Inorganic Nanostructures

2017

To combine several inorganic components with organic material in a controlled special and permanent manner still remains a difficult issue. Two specifically functionalized block copolymers were synthesized separately and combined in a second step. A heterofunctional poly(ethylene glycol) (PEG) block copolymer bearing a single amino unit, a short PEG spacer, and multiple catechol functionalities was obtained via anionic ring-opening polymerization (AROP). Using the reversible addition–fragmentation chain transfer (RAFT) radical polymerization technique, a semiconducting block copolymer with carbazole side groups was obtained. The second polyacrylate block contained reactive ester groups and …

Ester-functionalized poly(3-alkylthiophene) copolymers : synthesis, physicochemical characterization and performance in bulk heterojunction organic s…

2013

Abstract The introduction of functional moieties in the donor polymer (side chains) offers a potential pathway toward selective modification of the nanomorphology of conjugated polymer:fullerene active layer blends applied in bulk heterojunction organic photovoltaics, pursuing morphology control and solar cell stability. For this purpose, two types of poly(3-alkylthiophene) random copolymers, incorporating different amounts (10/30/50%) of ester-functionalized side chains, were efficiently synthesized using the Rieke method. The solar cell performance of the functionalized copolymers was evaluated and compared to the pristine P3HT:PCBM system. It was observed that the physicochemical and opt…