Linear poly , preparative

Trilialophenols can be converted to poly(dihaloph.enylene oxide)s by a reaction that resembles radical-initiated displacement polymerization. In one procedure, either a copper or silver complex of the phenol is heated to produce a branched product (50). In another procedure, a catalytic quantity of an oxidizing agent and the dry sodium salt in dimethyl sulfoxide produces linear poly(2,6-dichloro-l,4-polyphenylene oxide) (51). The polymer can also be prepared by direct oxidation with a copper—amine catalyst, although branching in the ortho positions is indicated by chlorine analyses (52). 

Preparation of Linear Poly(ethyleneimine) by Hydrolysis of Polyoxazoline... 

Other nutshell materials have been synthesised [164]. Hydrophobic latex particles containing a crosslinked poly(VBC) core and a macroporous poly(styrene/DVB) shell were prepared from concentrated o/w emulsions. Similarly, hydrophilic porous particles of crosslinked acrylamide surrounding a linear poly(ethyleneoxide) core were formed from w/o HIPEs. The poly(VBC) cores of the hydrophobic particles were quaternised and used to bind [Co(CO)4] anions, whereas the hydrophilic latexes were employed in the immobilisation of lipase. 

A polymer-supported Sharpless epoxidation catalyst was prepared using linear poly(tartrate ester) catalyst ligands 43.65 This catalyst system was used in the reaction of tranA-hex-2-en- l-ol with titanium tc/ra-isopropoxide and tert-butyl hydroperoxide to afford the desired epoxide in high chemical yield and moderate enantiomeric excess. 

Miller, Neenan, et al.129,301 reported a general single-pot method (Scheme 6.5) for the preparation of poly(arylether) hyperbranched macromolecules (14 a-d), that are functionally analogous to linear poly(arylether) engineering plastics.129-3 1 The hyperbranched polymers were generated from phenolic A2B-type monomers (15 a-d), that were converted to the corresponding sodium phenoxides (16 a-d NaH, THF) and subjected to polymerization. 

Poly(N-alkyl-ethylene imine) can be prepared by cationic ring-opening polymerization of N-alkylaziridines however, branched polymers are obtained by this way 19>. Linear poly-MEI may be obtained by N-methylation of linear PEI by the Clarke-Eschiweiler variation of the Leukart reaction, in which an excess of formic acid is used together with formaldehyde. The reaction may be performed either on PEI, or... 

The process for preparing linear poly-p-xylylenes by pyrolytic polymerization of di-p-xylylenes has been extended to include the formation of p-xylylene copolymers. Pyrolysis of mono-substituted di-p-xylylenes or of mixtures of substituted di-p-xylylenes results in formation of two or more p-xylylene species. Copolymerization is effected by deposition polymerization on surfaces at a temperature below the threshold condensation temperature of at least two of the reactive intermediates. Random copolymers are produced. Molecular weight of polymers produced by this process can be controlled by deposition temperature and by addition of mercaptans. Unique capabilities of vapor deposition polymerization include the encapsulation of particulate materials, the ability to replicate very fine structural details, and the ability of the monomers to penetrate crevices and deposit polymer in otherwise difficultly accessible structural configurations. 

A new general synthetic method for preparing linear poly-p-xylylenes - was reported recently (6, 7, 8, 9, 10, 11, 13). This new method involves the vacuum pyrolysis of di-p-xylylene or substituted di-p-xylyl-enes at temperatures of 600°-700°C. to form p-xylylenes and the subsequent condensation and spontaneous polymerization of these reactive species to form a family of linear polymers. The over-all reaction scheme is illustrated at the top of p. 644. 

Jeong, J.H., Song, S.H., Lim, D.W., Lee, H., and Park, T.G. (2001) DNA transfection using linear poly(ethylenimine) prepared by controlled acid hydrolysis of poly(2-ethyl-2-oxazoline). Journal of Controlled Release 73 391-399. 

Noncovalent self-assembly of complementary pairs of homoditopic building blocks (AA/BB-type), such as bis(crown ether) 125 and diammonium salt 126, has afforded well-defined supramolecular oligomeric/polymeric assemblies <2003JA3522>. In dilute solutions, entropy favored the formation of the cyclic dimer, whereas high equimolar concentration (>0.5 M) of the two components led almost exclusively to linear species aggregation, as revealed by H NMR analysis and viscosity measurements. Closely related linear poly[3]pseudorotaxane supramolecular arrays have also been prepared from cylindrical bis(crown ether) 127 and bisparaquat derivative 128 <2005CC1696>. 

In a more recent patent (45), Ryan prepared poly (n-butyl acrylate)/ poly (methyl methacrylate) latex semi-IPN s of the first kind. These materials were then blended into linear poly (vinyl chloride) and became a ternary polymer mixture. 

Flexible and oxidatively stable thermosets were prepared by thermally curing linear poly(silarylene-siloxane-acetylene) elastomers at up to 450°C. Thermooxidative weight loss of 3.69% to 7.69% was observed for these crosslinked inorganic-organic hybrid polymers when isothermed at 350°C under air flow. 

Preparation of High-Temperature Elastomer Precursor, Linear Poly(Silarylene-Siloxane-Acetylene)... 

Additional fexible and oxidatively high-temperature stable elastomers were prepared by the author [1,2] by thermal curing modified linear poly(silar-ylene-siloxane-acetylene) prepolymers, (I), and (II), respectively. 

Isoelectric focusing on polyacrylamide gels, freshly prepared, or on those stored in sealed bags obtained commercially, or on in house prepared, contain a number of char -acteristics that are undesirable, or even unknown A) Gel polymerization products remain in the gel. These consist of unpolymerized acrylamide monomers, linear poly -mers, breakdown products of acrylamide such as Nitrilotrispropionamide... 

This scheme was evolved after considerable experimentation demonstrated that linear poly (ortho esters) can only be prepared if the reactivity of one alkoxy on the ortho ester group is greatly diminished relative to the other two. If this is not done, only crosslinked products are isolated. Because alkoxy groups in an... 

After investigating a number of linear poly (ortho esters) a material prepared from 3,9-(bis ethylidene 2,4,8,10-tetraoxaspiro [5,5] undecane) and 1,6-hexa-nediol was selected as the best material [42]. Figure 23 shows results of a study where both 5FU release and weight loss were determined. The data show that with this particular system, concomitant drug release and polymer erosion has been achieved. Further, because the molecular weight of the residual polymer remains unchanged, the hydrolysis process is confined to the outer surface of the device and surface erosion has been achieved. 

In the initial approach, and before the action of acidic excipients was clearly understood, the slightly acidic and relatively water insoluble salt, calcium lactate, was used with the hopes of catalyzing long term surface erosion of linear poly (ortho esters). In this work, rod-shaped devices were prepared by incorporating 30 wt% levonorgestrei and 2 wt% calcium lactate into a polymer prepared from 3,9-bis (ethylidene-2,4,8,10-tetraoxaspiro [5,5] undecane) and a 60/40 mol mixture of trans-cyclohexane dimethanol and 1,6-hexanediol and the devices were implanted into rabbits. The devices were then explanted at various time intervals and examined by scanning electron microscopy. A device ex-planted after 10 weeks is shown in Fig. 27 [25]. 

William F. Gorham. A New, General Synthetic Method for the Preparation of Linear Poly- l2,pi/Ii-xylylenes. Journal of Polymer Science Part A-1 Polymer Chemistry, 4(12) 3027-3039, 1966. 

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