Organic Side Groups Research Articles

Synthesis of poly[bis(phosphazo)phosphazenes] bearing aryloxy and alkoxy side groups

The synthesis of a new class of phosphazene polymers through the thermal ring-opening polymerization of the cyclotriphosphazene gem-(NPCl 3 ) 2 N 3 P 3 Cl 4 (1), is reported. The resultant polymer possesses controlled short-chain branching sites along the phosphazene backbone. The chlorine atoms in this polymeric intermediate were replaced by organic side groups to yield novel organic-inorganic polymers that are stable to ambient conditions

Absorption, emission and lifetimes of [2,2′ -bipyridyl]-3,3′-diol in sol-gel glasses and in polymethylmethacrylate

Spectral behaviour and quantum yields of [2,2′-bipyridyl]-3,3′ -diol (BP (OH) 2) in sol-gel glasses modified by organic sidegroups were studied and compared with the properties of BP (OH) 2 in solutions, in a plain sol-gel glass and in polymethylmethacrylate (PMMA). Fluorescence intensity of the dye in a fresh sol-gel glass is similar to that in water while the corresponding blue-shift is smaller and hints at the “cage effect”. The overall spectral behaviour of the dye in organically modified sol-gel glasses is similar to that observed in some polar solvents and in PMMA, while the fluorescence intensity is higher and lifetimes are longer. This increase is ascribed to the rigidity of the silica-polymer network in these glasses.

Ring expansion and equilibration in organophosphazenes and the relationship to polymerization

A series of cyclic trimeric phosphazenes that bear both halogen and organic side groups have been found to undergo ring expansion-equilibration reactions at elevated temperatures. Compounds N 3 P 3 F 5 CMe 3 , N 3 P 3 F 5 Ph, non-gem-N 3 P 3 F 4 (CMe 3 ) 2 , N 3 P 3 F 4 Ph 2 , N 3 P 3 Cl 4 Me 2 , N 3 P 3 Cl 4 Et 2 , N 3 P 3 Cl 3 Me 3 , and N 3 P 3 Cl 3 Et 3 yield cyclic tetramers, pentamers, hexamers, and, in some cases, heptamers, octamers, and nonamers when heated. The cyclic tetramers (NPClMe) 4 and (NPClEt) 4 also equilibrate to a range of cyclic species that range from trimer to hexamer. Several of these equilibrations also lead to the formation of high polymers. The results are discussed in terms of possible mechanisms for ring-ring equilibration and polymerization

Influence of different organic side groups on the thermal behavior of polyphosphazenes: random chain cleavage, depolymerization, and pyrolytic cross-linking

Influence of different organic side groups on the thermal behavior of polyphosphazenes: random chain cleavage, depolymerization, and pyrolytic cross-linking

Mesomorphic phases of poly(DI‐n‐alkylsiloxane)s

AbstractThe phase behavior of poly(dialkylsiloxane)s which are symmetrically substituted with ethyl, n‐propyl, and n‐butyl side groups has been investigated by solid state NMR and differential scanning calorimetry. All polymers exhibit disordering transitions before isotropization. The observation of conformational and motional changes is correlated to the different thermal transitions. Diffusive rotation of the chain segments around the molecule long axis is indicated by 29Si‐NMR below the isotropization transition. The remarkably fluid character is explained in part by the coexistence of anisotropic and isotropic motional states of the ‐OSiEt2‐ segments. Molecular motion below the upper disordering transition is restricted but still fast with respect to the 29Si‐NMR time scale. Long range reorganization processes have to be considered to explain the difference between α2‐PDES and β2‐PDES. The stepwise disordering at the onset of different motional processes, which results in the formation of a columnar liquid crystalline phase of these highly flexible chain molecules, is discussed with respect to the amphiphilic constitution of the molecules having an inorganic backbone substituted by organic side groups.

Anionic polymerization of cyclic organosilicon compounds. Review

Abstract The anionic polymerization of organocyclosiloxanes and organospirocyclosiloxanes is described and the mechanism of polymerization of organocyclosiloxanes is discussed. It is shown that in the case of monocyclic compounds polymerization involves a stage of formation of an organocyclosiloxane-catalyst molecular complex. The effect of the organic side groups on the polymerization reaction is studied. it is shown that polymerization of organospirocyclosiloxanes is a complex process and that when bulky organic radicals are involved a spirocyclosiloxane rather than a network structure is obtained.

Inorganic coordination polymers. XVIII. Observations on brittle and flexible films of {Cr[OP(CH3)(C6H5)O]2[OP(C8H17)2O]}x

AbstractFilms of {Cr[OP(CH3)(CH6H5)O]2[OP(C8H17)2O]}x, formed during the reaction of {Cr(OH)[OP(CH3)(C6H5)O]2}x with dioctylphosphinic acid, are either brittle or flexible depending on the details of the preparation of the chromium(III) bisphosphinate precursor. Both kinds of film appear to contain mainly triple‐bridged chains. Differing degrees of randomness in distribution of the two kinds of phosphinate bridges and, hence, of the internally plasticizing octyl groups along the chain account for the observed differences in flexibility, x‐ray diffraction patterns, and birefringence. The observed intrinsic viscosities of 9–18 dl/g indicate that these trisphosphinates form microgels rather than true solutions. The thermal degradation of these films proceeds by the oxidation and cleavage of the organic side groups. Addition of antioxidants to the flexible films significantly increases the longevity of their flexibility at 200°C.

CHAPTER 4: INORGANIC PHOSPHORUS POLYMERS

Abstract The term inorganic polymers comprises polymers whose main chains (linear, branched, or cross-linked) have no carbon atoms. The side groups may contain carbon. Obviously, inorganic polymers with organic side groups are particularly interesting because the physicomechanical properties required of plastics, such as plasticity, elasticity, solubility. fusibility, etc., are primarily obtained by introducing organic groups into inorganic polymer chains. In this text, reference is made to the commonly known differences between polysilicates and polysiloxanes (silicones). The great interest attached to inorganic polymers is due mainly to the search for plastics of high thermal stability. Various recent reviews summarizing the theoretical and experimental findings [G8,H6,Ll,Sl5,Y3] are available on inorganic polymers. Phosphorus-containing inorganic polymers have been included in all these monographs.