Nonionic triblock copolymer

Pluronic-g- polyethyleneimine (Pluronic-g-PEI) Graft-copolymer, branched PEI segment grafted with nonionic triblock copolymer In vitro and in vivo transfections and oligonucleotide delivery (Nguyen etal., 2000)... 

The nonionic triblock copolymer polyethylene oxide-polypropylene oxide polyethylene oxide (PEO-PPO-PEO) has been widely used in medicine and has shown low toxicity. Wanka et al. [91] studied aggregation behavior of PEO-PPO-PEO polymeric micelles. In this study, the hydrophobic core of this micellar system consisted of dehydrated poly(oxy-propylene) groups which were surrounded by an outer shell of hydrated poly(oxyethylene) groups. The feasibility of using PEO-PPO PEO micelles as a topical ocular carrier for gene delivery was addressed in an in vivo study on nude mice and albino rabbits [92], Each animal eye was treated with a topical application (10 pL for mouse and 50 pL for rabbit) of 0.08 mg/mL of plasmid and 0.3% (w/v) PEO-PPO-PEO polymeric micelles. After 2 days of three times per day topical delivery, the reporter expression was detected in the treated eyes... 

The typical procedure (42) involved mixing 4 g of nonionic triblock copolymer L123 (BASF), 20 g of water, and 80 g of 2M HC1. To this solution, 8 g of tetraethylorthosilicate was added at room temperature. The mixture was then stirred at room temperature for 24 h. The solid product was recovered by filtration. The polymer template was removed by calcination at 500°C for 5 h. 

The effect of addition of NaCl to a nonionic triblock copolymer templated silica synthesis was investigated by Alfredsson et who showed that NaCl made the aqueous solution more polar and thus a worse solvent... 

Pore size in EISA materials can be adjusted by changing the size of the surfactant micelles with both small cationic surfactants and larger nonionic triblock copolymer surfactants used to prepare films. While triblock copolymer surfactants of the EO-PO-EO family can be used to make... 

Figure 2.16 Typical nitrogen adsorption-desorption isotherms at 77K for (a) MCM-41 materials templated with alkyltrimethylammonium bromide surfactants with hydrophobic tails of different lengths as indicated (volumes adsorbed for C12, C14, C16 and C18 were incremented by 200, 400, 600 and 800 ml(STP) g, respectively) and (b) nonionic triblock copolymer templated SBA-15 silicas synthesised at different temperatures (volumes adsorbed for 353 K and 373 K were incremented by 200 and 400 ml(STP) respectively). The hysteresis loops observed in this case are typical of the larger mesopores in these materials. Desorption points are represented by closed symbols. Reprinted with permission from Morishige, K. Tateishi, M., Accurate relations between pore size and the pressure of capillary condensation and the evaporation of nitrogen in cylindrical pores, Langmuir, 22, 4165 169. Copyright (2006) American Chemical Society...

Poly(ethylene oxide)/Poly(propylene oxide)/ Poly(ethylene oxide) Triblock Copolymer Pluronic is a trade name for poloxamers, which are nonionic triblock copolymers of PEO chains on the two ends of the molecules with a poly(propylene) oxide (PPO) chain in the middle. The PEO chain is hydrophilic, while the PPO chain is hydrophobic. The polymer properties can be tailored depending on the content ratio of the constituents. Due to the combined hydro-phobic and hydrophilic properties in the structure (amphiphilic), it can be used as a stabilizer and a surfactant. It also can enhance miscibility and water absorption of polymers, and it has low toxicity itself. Pluronic has been used in drug delivery devices for controlled release purposes [220]. 

Ke, Y., C. L. McGraw, R. L. Hunter and J. A. Kapp, 1997, Nonionic triblock copolymers facilitate delivery of exogenous proteins into the MHC class I and class II processing pathways. Cell Immunol 176 113-121. 

In a thorough and critical examination of the work on the kinetics of micellization of nonionic triblock copolymers published during 1996-2001, Thum et al. noticed the claim that the fast relaxation time associated with the single monomer/micelle exchange exists in two different time domains, namely, 10 to 10 sec (TJ) and 10 sec (UAS) for the same tiiblock copolymers. No satisfactory explanations could be found in the literature. In order to resolve this serious... 

Thurn, T., Couderc-Azouani, S., Bloor, D.M., Holzwarth, J.F., Wyn-Jones, E. Ultrasonic relaxation in micellar solutions of nonionic triblock copolymers. Langmuir 2003, 79(10), 4363 370. 

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