Studies on the block copolymerization of <scp>D</scp>,<scp>L</scp>‐lactide and poly(ethyle glycol) with aluminium complex catalyst

Deng, Xianmo; Xiong, Chengdong; Cheng, Lijun; Huang, Henghui; Xu, R. P.

doi:10.1002/app.1995.070550806

Cited by 49 publications

(23 citation statements)

References 3 publications

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“…For multiblock copolymers of P(LA-co-GA) and PEO, the NHD rate traced by weight loss became higher with an increase in P(LA-co-GA) and PEO block lengths, whereas that monitored by molecular weight was similar in both cases when compared at a similar ratio of P(LA-co-GA) to PEO. For the NHD of PDLLA-b-PEOb-PDLLA or PDLLA-poly(tetramethylene ether glycol) block copolymers under uncontrolled pH in an NaCl solution, the degradation rate traced by viscometry decreased with an increase in the content of relatively hydrophobic polyethers [209,216].…”

Section: Molecular Structurementioning

confidence: 99%

Hydrolytic Degradation

Tsuji

2010

Poly(Lactic Acid)

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Section: Molecular Structurementioning

confidence: 99%

Hydrolytic Degradation

Tsuji

2010

Poly(Lactic Acid)

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“…Deionized water (15-30 ml) was pumped onto the spin-coated polymer surface at a rate of 1 ml Á s À1 . Images (20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30) were recorded. The contact angles were calculated by averaging measurements from a series of images.…”

Section: Advancing Contact Anglementioning

confidence: 99%

“…stannous octoate, SnO, SnO 2 , Sb 2 O 3 , PbO, GeO 2 , SnCl 2 , zinc powder, and NaH. [13,[19][20][21][22][23][24][25][26][27][28] Among these catalysts, stannous octoate is the most frequently mentioned in literature because it leads to high yield and high molecular weights. [21,27] There have been several reports of the synthesis of PLA and PEG diblock and triblock copolymers together with some detailed information on the bulk microstructure and their physical properties.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and Characterization of Block Copolymers of Polyoxyethylene and Polylactide with Different Architectures

Mai

Abbot

Norton

et al. 2009

Macro Chemistry & Physics

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Diblock and triblock copolymers were prepared from polyethylene glycol (PEG, $\overline M _{\rm n}$ = 2 000), L‐lactide and D,L‐lactide. A novel method was developed to prepare high‐molecular‐weight multiblock copolymers by transesterification of a PEG/succinic acid polyester with poly(L‐lactide). Molecular weights were monitored by GPC and overall composition was checked by 1H NMR. Crystallinity, bulk microstructure, and the glass transition were investigated by DSC and simultaneous SAXS/WAXS/DSC, and surface properties by measurement of advancing contact angle. It is found that the crystallization of the poly(ethylene oxide) (PEO) block is very much affected by the position of the PEO block in the copolymer and by the length and the state of the polylactide block. Both DSC and WAXS showed that the crystallization of PEG2000 block was very much suppressed when covalently bonding to polylactide (PLA) blocks. These methods also confirmed good miscibility between amorphous PLA and PEG blocks. The preparation of fiber by electrospinning demonstrates the target application of the multiblock copolymers in tissue engineering.magnified image

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“…Comonomers are often introduced to control the distribution of water. Hydrophilic moieties, typically poly(ethylene glycol) (PEG), also called poly(ethylene oxide) (PEO), are often incorporated into a polymer to increase the water uptake and accelerate degradation [3–4]. Incompatibility between hydrophobic and hydrophilic segments can lead to phase separation [5].…”

Section: Introductionmentioning

confidence: 99%

Study of nanoscale structures in hydrated biomaterials using small-angle neutron scattering

Luk¹,

Murthy²,

Wang³

et al. 2012

Acta Biomaterialia

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Distribution of water in three classes of biomedically relevant and degradable polymers was investigated using small-angle neutron scattering. In semicrystalline polymers, such as poly(lactic acid) and poly(glycolic acid), water was found to diffuse preferentially into the noncrystalline regions. In amorphous polymers, such as poly(D,L-lactic acid) and poly(lactic-co-glycolic acid), the scattering after 7-days of incubation was attributed to water in microvoids that form following the hydrolytic degradation of the polymer. In amorphous copolymers containing hydrophobic segments (desaminotyrosyl-tyrosine ethyl ester) and hydrophilic blocks (poly(ethylene glycol) PEG), a sequence of distinct regimes of hydration were observed: homogeneous distribution (~ 10 Å length scales) at <13 wt% PEG (~ 1 water per EG), clusters of hydrated domains (~50 Å radius) separated at 24 wt% PEG (1 to 2 water per EG), uniformly distributed hydrated domains at 41 wt% PEG (~ 4 water per EG), and phase inversion at > 50 wt% PEG ( > 6 water per EG ). Increasing PEG content increased the number of these domains with only a small decrease in distance between the domains. These discrete domains appeared to coalesce to form submicron droplets at ~60 °C, above the melting temperature of crystalline PEG. Significance of such observations on the evolution of μm size channels that form during hydrolytic erosion is discussed.

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Studies on the block copolymerization of D,L‐lactide and poly(ethyle glycol) with aluminium complex catalyst

Cited by 49 publications

References 3 publications

Hydrolytic Degradation

Hydrolytic Degradation

Synthesis and Characterization of Block Copolymers of Polyoxyethylene and Polylactide with Different Architectures

Study of nanoscale structures in hydrated biomaterials using small-angle neutron scattering

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