Polymer modification substituent

A convenient alternative to protection relies on the incorporation of a labile moiety available for post-polymerization functionalization by nucleophilic substitution [84]. A more versatile approach incorporates a terminally halogenated alkyl substituent as a site for post-polymerization via nucleophilic substitution. Anthraquinone, amine, thiol and carboxylic acid derivatives have been prepared thereby. Complete conversion is possible [46, 47]. Irregular examples include conversion to iodo and thiol derivatives [85]. 

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Polymer Modification. The introduction of functional groups on polysdanes using the alkah metal coupling of dichlorosilanes is extremely difficult to achieve. Some polymers and copolymers with 2-(3-cyclohexenyl)ethyl substituents on siUcon have been made, and these undergo hydrogen hahde addition to the carbon—carbon double bond (94,98). 

A series of novel styrene- and siloxane-based silanol polymers and copolymers were synthesized by a selective oxidation of the Si—H bond with a dimethyldioxirane solution in acetone from corresponding precursor polymers. The conversion of the Si—H to Si—OH in the polymer modification proceeded rapidly and selectively. The silanol polymers obtained in situ showed no tendency for self-condensation to form siloxane crosslinks in solution. Moreover, stable silanol polymers in the solid states were obtained by placing bulky substitute groups bonded directly to the silicon atom. It was found that the properties of these novel silanol polymers and copolymers depended largely on substituents bonded directly to the silicon atom and silanol composition in the copolymers as well. 

Most observations of rate retardation in polymer modifications have been attributed to steric hindrance. In order to estimate the steric influence of the relatively bulky triethyIbenzylammonium substituent on unreacted site during quaternization, quinuclidine was chosen as nucleophile. It is well known that nucleophilicity of quinuclidine in displacement reactions is greater than that of triethylamine, since bicyclic amines are less sterically hindered. Preliminary experiments on the quaternization of chloromethylated polysulfone with quinuclidine in DMSO showed that the reaction velocity was too rapid to investigate using our experimental techniques, i.e., 85% conversion was obtained with three minutes. Therefore, we were forced to add a less polar solvent to DMSO in order to reduce the reaction rate. It was found that a 50 50 (v/v) mixture of dioxane and DMSO dissolved both chloromethylated and quaternized polysulfone so the rate could be measured in a homogeneous system. The introduction of a nonpolar solvent reduced the initial rate of triethylamine substitution fourfold (Table III, run 17). 

Analytical and Test Methods. Most of the analytical and test methods described for THF and PTHF are appHcable to OX and POX with only minor modifications (346). Infrared and nmr are useful aids in the characterization of oxetanes and their polymers. The oxetane ring shows absorption between 960 and 980 cm , regardless of substituents on the ring (282). Dinitro oxetane (DNOX) has its absorption at 1000 cm . In addition, H-nmr chemical shifts for CH2 groups in OX and POX are typically at 4.0—4.8 5 and 3.5—4.7 5, respectively (6,347,348) C-nmr is especially useful for characterizing the microstmcture of polyoxetanes. 

The same fluoroalkoxy substituents, however, are able to enhance substitutional reactivity of fluorinated polyphosphazenes by originating methatetical exchange reactions on polymers in the presence of new nucleophiles and under appropriate experimental conditions. Thus, a series of exchange reactions at phosphorus atoms bearing the trifluoroethoxy substituents in PTFEP have been describedbyH.R. Allcock [508] (Fig. 13),Cowie [482,483] (Fig. 14), and Ferrar [509] (Fig. 15), while surface modification of PTFEP films were reported by Allcock [514,515] (Fig. 16 or 17) and by Lora [516] (Fig. 18). 

Unsaturated groups are very interesting for application development because this specific functionality opens up a broad range of possibilities for further (chemical) modification of the polymer structure, and therefore its physical and material properties. The direct microbial incorporation of other functional substituents to the polymer side chains, e.g. epoxy-, hydroxy-, aromatic-, and halogen functional groups, influences the physical and material properties of poly(HAMCL) even further [28,33,35,39-41]. This features many possibilities to produce tailor-made polymers, depending on the essential material properties that are needed for the development of a specific application. 

Almost all modifications in PF homopolymers consist of variation of substituents at position 9 of the fluorene nucleus. Recently, Beaupre and Leclerc [303] reported a new synthetic strategy to polymers 201 and 202 with the aim to modulate the 7P of the PFs (for better injection of holes from the anode in LED) by introducing donor 3,6-dimethoxy substituents into the fluorene moiety (Scheme 2.27). The d>PL of polymer 201 is relatively low (48%), but it... 

Exploiting the known reactivities of chlorocyclopropylideneacetates 1 -3, the synthesis of a compound library from polymer-bound chlorocyclopropylidene-acetic acid 1-H has been realized in a sequence of transformations as shown in Scheme 77 [127], following attachment of the acid 1-H to a resin (A), a Michael addition of nucleophile (B), nucleophilic substitution of the chlorine (C), modification of one of the substituents (D) and cleavage of the substrate to polymer bond (E). 

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