نتایج جستجو برای: copolymers

تعداد نتایج: 8591  

2015
Daniel Görl Xin Zhang Vladimir Stepanenko Frank Würthner

New synthetic methodologies for the formation of block copolymers have revolutionized polymer science within the last two decades. However, the formation of supramolecular block copolymers composed of alternating sequences of larger block segments has not been realized yet. Here we show by transmission electron microscopy (TEM), 2D NMR and optical spectroscopy that two different perylene bisimi...

Journal: :Acta pharmaceutica 2004
Aleksandra Porjazoska Katerina Goracinova Kristina Mladenovska Marija Glavas Maja Simonovska Emilija Ivanovska Janjević Maja Cvetkovska

Poly(DL-lactide-co-glycolide) (PDLLGA) and poly(L-lactide-co-glycolide) (PLLGA) copolymers were prepared by bulk ring opening polymerization of lactide and glycolide and characterized by GPC, FTIR, 1H NMR and DSC. Copolymers with different molar masses at a constant lactide/glycolide ratio were used for preparation of bovine serum albumin (BSA)-loaded microparticles by the double emulsion w/o/w...

1997
Jeffrey Mecham Thomas C. Ward James F. Wolfe James E. McGrath

(ABSTRACT) Linear thermoplastic polyesters are commonly used in high volume applications such as food containers, films and textile fibers. The physical and mechanical properties of these materials are well documented and are a function of chemical structure and morphology (e.g. semi-crystalline, amorphous, etc.). Polyesters, as are many organic polymers, are quite flammable. Polydimethylsiloxa...

2017
Yuushou Nakayama Kazuki Aihara Zhengguo Cai Takeshi Shiono Chikara Tsutsumi

Although the copolymerizations of l-lactide (LA) with seven- or six-membered ring lactones have been extensively studied, the copolymerizations of LA with four-membered ring lactones have scarcely been reported. In this work, we studied the copolymerization of LA with β-propiolactone (PL) and the properties of the obtained copolymers. The copolymerization of LA with PL was carried out using tri...

2018
Ana Rey-Rico Magali Cucchiarini

Lineal (poloxamers or Pluronic®) or X-shaped (poloxamines or Tetronic®) amphiphilic tri-block copolymers of poly(ethylene oxide) and poly(propylene oxide) (PEO-PPO-PEO) have been broadly explored for controlled drug delivery in different regenerative medicine approaches. The ability of these copolymers to self-assemble as micelles and to undergo sol-to-gel transitions upon heating has endowed t...

2010
David Valade Frédéric Boschet Bruno Améduri

Fluorinated copolymers bearing ammonium groups were prepared by radical copolymerization of fluorinated olefins (chlorotrifluoroethylene, hexafluoropropylene) with different vinyl ethers (2-chloroethyl, cyclohexyl, n-butyl, and ethyl vinyl ethers) followed by the cationization of these copolymers with trimethylamine. Copolymers were obtained in high yield (generally > 85 %), with molecular weig...

2003
Li Guang

Segmented polyesteramides have been synthesized from N,N'-bis(p-carbomethoxybenzoy)butanediamine as crystalline segments and mixtures of poly(tetramethylene oxide) (mol. wt. 1000) and 1,5-pentanediol as soft segments. The polymerization was carried out in the melt at 250°C for I h while vacuum was applied. The melting behaviour of the copolymers was studied by differential scanning calorimetry....

2015
Shota Somekawa Kazunari Masutani Atsushi Mahara Yoshiharu Kimura Tetsuji Yamaoka

The ability to control the micelle size of poly(lactic acid) and poly(ethylene glycol) (PLA–PEG) block copolymers is important for controlling their circulation in blood cell recognition, drug release and therapeutic effects. We successfully controlled the micelle size by changing the block number of copolymers (multiblock index). PLA–PEG multiblock copolymers with multiblock indexes ranging fr...

2015
J. P. MacDonald M. P. Parker B. W. Greenland D. Hermida-Merino I. W. Hamley M. P. Shaver

Four alkyl substituted β-lactones were investigated as monomers in ring opening polymerisation to produce a family of poly(3-hydroxyalkanoate)s. Homopolymers were synthesised using a robust aluminium salen catalyst, resulting in polymers with low dispersity (Đ < 1.1) and predictable molecular weights. ABA triblock copolymers were prepared using poly(L-lactic acid) as the A block and the aforeme...

2014
R. CHITRA E. KAYALVIZHY P. JEYANTHI P. PAZHANISAMY

7-Acryloyloxy-4-methylcoumarin (ACU) monomer was polymerized with N-cyclohexylacrylamide (NCA) in different feed ratio using AIBN (Azobisisobutyronitrile) as initiator in DMF. The copolymers were characterized by H NMR spectroscopy and the copolymer compositions were determined by H NMR analysis. The reactivity ratios of monomers were determined using linear methods like Fineman-Ross and Kelen-...

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