PBMA

Barton et al.1X7 have reported that primary radical termination between PBMA and cyanoisopropyl radicals (7) involves largely disproportionation. 

Kobetaki et a/. 89 642 have examined the combination of conventional free radical and NMP to prepare PBMA-Woci-PS and the combination of anionic and NMP to prepare PB-6/oc -PS. 

PBMA with PMMA 255.257 PF. with PMAN 257 PMAN with PS- 257 cumene hydroperoxide, as initiator 92 cumy I dilhiobcrzoulc see ditliioberzome R A FT agents... 

SFE has also been used to analyse phenanthrene in PET and PMMA [404]. Nazem and Taylor [405] used SFE to determine antioxidant (Irganox 1010/1076, Irgafos 168) recovery from variously TEGDMA cross-linked polymethacrylates (PMMA, PEMA, PBMA). 

GFR Glass-fibre reinforced PBMA PBT Poly(butyl methacrylate) Poly(butylene terephthalate)... 

The divinyl compound approach has been extensively covered in previous reviews. However, an interesting example for the synthesis of A2B2 4/z-stars, where A is either PI or PBd and B is PMMA or PBMA, has recently been prepared [177]. Following polymerization of the diene in hexane by s-BuLi,... 

Poly(butyl methacrylate) (PBMA) began to be used as a picture varnish in the early 1930s. It encountered a considerable success because of its resistance to yellowing, adequate flexibility, no dirt pick-up and good solubility in nonpolar hydrocarbon solvents. Products based on PBMA, such as Elvacite 2044 and Elvacite 2045 by Du Pont, were abandoned when it was discovered that under light exposure they cross-link to an unexpected extent becoming insoluble [64]. From this point of view acrylic copolymers based on methyl and ethyl acrylates/methacrylates show a much better long-term stability. 

This analysis leads to the conclusion that equation 1 is obeyed well by certain anthracene/polymer combinations, but there are significant deviations for others. DMA/PEMA (poly(ethyl methacrylate)) and DPA/PBMA (poly(butyl methacrylate)) fit equation 1 exactly, while DPA/PEMA (both with and without sensitizer) and DPA/PDPS (poly(diphenylsiloxane)) deviate the actual reaction proceeds more slowly with dose than predicted, and the deviation increases as the dose increases. 

The parameter [3 is related to the contrast. If (3A> > 1, equation 1 reduces to that of a simple first order reaction (such as CEL materials are usually assumed to follow (6)). If 3A< < 1, the reaction becomes second order in A In a similar manner, the sensitized reaction varies between zero order and first order. For the anthracene loadings required by the PIE process (13,15), A is close to 1M, so (3 > > 1 is required for first order unsensitized kinetics. Although in solution, 3 for DMA is -500, and -25 for DPA (20), we have found [3 =3 for DMA/PEMA, and (3=1 for DPA/PBMA. Thus although the chemical trends are in the same direction in the polymer as in solution, the numbers are quite different, indicating a substantial... 

Carboxyl terminated PSt (PSt-COOH) and carboxyl-terminated PBMA (PBMA-COOH) were also prepared by radical polymerization using 3-mercaptopropionic acid (MPA) as a chain transfer agent and purihed by precipitation in a large excess of MeOH [24,25]. The polymer product was obtained as a white powder by lyophilization. 

Micelle solutions of PlPAAm-Ci8H35 was prepared by direct dissolution of the polymer in cold water (4°C) due to its good water solubility [23]. Each solution of PIPAAm-PSt, PlPAAm-PBMA, and PIPAAm-PLA was prepared by dissolving each copolymer in DMF, A-ethylacetamide, and DMAc, respectively. The solutions were put into a dialysis bag (MWCO = 13,000) and dialyzed against distilled water at 10°C, 20°C, and 4°C, respectively, for 24 hours. The micelles were purified with ultrafiltration membrane of 200,000 molecular weight cut off at 4°C. The aqueous solution was lyophilized to leave a white powder of micelles. 

Polymeric micelles with selected chemistries and molecular architecture of block copolymers, such as PIPAAm-CigHgs, PIPAAm-PSt, PIPAAm-PBMA, and PIPAAm-PLA micelles, showed the same LCST and the same thermoreponsive phase transition kinetics as those for PIPAAm irrespective of the hydrophobic segment incorporation. This confirms two points (a) that hydroxyl groups or amino goups of PIPAAm termini completely react with the hydrophobic segment end groups and (b) that the block copolymers form core-shell micellar structures with hydrophobic iimer cores completely isolated from the aqueous phase. 

Figure 2 Plot of the ratio of intensities (/1//3) of the vibrational bands in the pyrene fluoreseenee speetrum as a funetion of temperature for PIPAAm (a), PIPAAm-CigHjs and PIPAAm-PBMA (b), = 340 nm, [pyrene] = 1.6 x 10 M, l°C/min, [polymer] = 5,000 mg/L.

ADRIAMYCIN (ADR) INCORPORATION INTO PIPAAm-PBMA MICELLES... 

PIPAAm-PBMA block copolymers form a micellar structures by selfassociation of the hydrophobic PBMA segments in water, a good solvent for PlPAAm chains below the LCST but a nonsolvent for the PBMA chains. This amphiphilic system produces stable and monodispersed micelles from polymer/A-ethylacetamide (good solvent for the both polymer blocks) solutions dialyzed against water. Hydrophobic dmgs can be physically incorporated into the iimer micelle cores with PBMA chains by hydrophobic interactions between the hydrophobic segments and dmgs. 

Figure 4 Drug (ADR) release from thermoresponsive PIPAAm-PBMA micelles containing ADR [27]. 

Shown in Figure 6 is in vitro cytotoxic activity of PIPAAm-PBMA micelles loaded with ADR or micelles without ADR at 29°C (below the LCST) and at 37°C (above the LCST) compared with that of free ADR. In vitro cytotoxic activity was measured using bovine aorta endothelial cells. Bovine aortic endothelial cells were obtained as previously reported using dispase for cell dissociation from freshly harvested bovine aorta [13]. The cells plated at a density of 3 x cells/well, were exposed with free ADR or micelles loaded with ADR at below and above the LCST for 5 days. In order to assay cytotoxicity of the free ADR or micelles loaded with ADR, culture medium was replaced with 10% FBS-supplemented phenol red-free DMEM containing 10% alamar Blue, a dye that is subject to reduction by cytochrome c activity and changes the color from blue to red [38]. After 4-hour incubation, reduction of the dye was estimated by absorbance at 560 and 600 nm. PIPAAm-PBMA polymeric micelles loaded with ADR showed higher cytotoxic activity than that of free ADR at 37°C (above the LCST)... 

Figure 6 In vitro cytotoxicity of free ADR (0.1 jxg/mL) and thermoresponsive PIPAAm-PBMA micelles containing ADR (0.1 jxg/mL) against bovine aorta endodieUal cells at 29°C (below the LCST) and 37°C (above the LCST). Incubation time 4 days.

Chart 2.6 Structure of block copolymer based on PEO and poly(benzyl methacrylate) (PBMA) containing /3-D-galactose unit. 

Cloud point curves measured for the blends of STHFS with PMMA, PEMA and PBMA, all had LCST, as expected for blends with specific interactions, and depended strongly on the degree of PS modification. For example, the lowest... 

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