Compositional analysis of biodegradable polyphosphoester copolymers using nmr spectroscopic methods

Zhao

J of Applied Polymer Sci

et al. 2010

Myosin XVA is an unconventional myosin which has been implicated in autosomal recessive nonsyndromic hearing impairment (ARNSHI) in humans. In Myo15A mouse models, vestibular dysfunction accompanies the autosomal recessive hearing loss. Genomewide homozygosity mapping and subsequent fine mapping in two Turkish families with ARNSHI revealed significant linkage to a critical interval harboring a known deafness gene MYO15A on chromosome 17p13.1‐17q11.2. Subsequent sequencing of the MYO15A gene led to the identification of a novel missense mutation, c.5492G → T (p.Gly1831Val) and a novel splice site mutation, c.8968 − 1G → C. These mutations were not detected in additional 64 unrelated ARNSHI index patients and in 230 Turkish control chromosomes. Gly1831 is a conserved residue located in the motor domains of the different classes of myosins of different species. Molecular modeling of the motor head domain of the human myosin XVa protein suggests that the Gly1831Val mutation inhibits the powerstroke by reducing backbone flexibility and weakening the hydrophobic interactions necessary for signal transmission to the converter domain. © 2007 Wiley‐Liss, Inc.

Section: Introductionmentioning

confidence: 99%

Synthesis of poly(D,L‐lactic acid) modified by cholic acid via direct melt copolycondensation and its characterization

Zhao

J of Applied Polymer Sci

et al. 2010

“…Chemically-modifying PLA is another attractive route to imparting inherent ame retardancy, and while the literature is lean of such examples, reports of PLA with demonstrated or inferred ame retardancy exist. PLA copolymerized 27 or chainextended 28,29 with phosphorus compounds, for example, are desired for their potential biological activity, and such reports hint at potential ame retarding characteristics. FR-PLA via sidechain modication with halogen or phosphorus functionalities is plausible with the recent introductions of functionalized lactide monomers, [30][31][32][33][34] although, to the best of our knowledge, such techniques have not been applied to developing FR-PLA formulations.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and characterization of isosorbide-based polyphosphonates as biobased flame-retardants

et al. 2014

A new isosorbide-based polyphosphate was synthesized and applied as a flame-retardant for polylactic acid (PLA). The storage modulus and glass transition temperature of PLA/polyphosphonate blends was unaffected by the inclusion of polyphosphonate, but moderate depressions of PLA's tensile strength (16%, 28%, and 45% reduction from PLA at a polyphosphonate mass percentage of 5%, 10%, and 15%, respectively) and strain-at-break (0%, 17%, and 30% reduction from PLA at a polyphosphonate mass percentage of 5%, 10%, and 15%, respectively) were observed. Modified UL-94 flammability testing indicated that isosorbide-based polyphosphonates are effective flame retardants for PLA and are able to self-extinguish flames in less than 2 s to achieve V2 and V0 ratings at polyphosphonate mass percentage of 5% and 15%, respectively. Fire test data indicates a gas phase mechanism that can quench the flame when no external radiant heat flux is present (e.g., in modified UL-94 testing) but does not affect the material's heat release rate in forced combustion (e.g., in cone calorimetry). Use of the biobased flame retardants described herein yields flame retardant PLA containing up to 97% by mass of bio-derived content.

J of Applied Polymer Sci

“…The result was consistent very well with the fact that all three isomers of BPGF were random, chemically bonded into polymer chains. Chaubal24 et al obtained the same result as they studied the chemical structure of a polymer resulting from poly( DL ‐lactide) and EDP, they also got three peaks (−1.6, −1.9, −2.4 ppm) in 31 P spectrum of polymer. They studied this phenomenon by model compound and concluded that these results were due to different bonding sequence of P‐O bond.…”

Section: Resultsmentioning

confidence: 61%

Synthesis of unsaturated polyphosphoester as a potential injectable tissue engineering scaffold materials

Qiu¹,

Liu²,

Hu³

et al. 2006

Polyphosphoester is a kind of biodegradable polymer with excellent biocompatibility and have been used in drug delivery, tissue engineering, and other bioapplications. A novel unsaturated polyphosphoester (UPPE) based on bis(1,2-propylene glycol) fumarate (BPGF) and ethyl dichlorophosphate was synthesized by polycondensation reaction, and crosslinkable double bonds was introduced into the resulting polymer through the fumarate groups. NMR results indicate that there are three possible bonding models in polyphosphoester because of three isomers of BPGF. The GPC results express that increase in polymerization time leads to high molecular weight of polyphosphester and narrow distribution of molecular weight. After 18 h of polymer-ization reaction, the molecular weight reached to 5956 g mol Ϫ1 and the polydispersity index was 1.12. The UPPE was soluble in N-vinyl pyrrolidone and easily crosslinked by free-radical polymerization. At the constant temperature (37°C), the maximum temperature due to heat release during crosslinking reaction varied from 41.1°C to 82.30°C and the setting time was between 1.95 and 10.28 min, according to different formulas.