Polysilane-poly copolymers

When neat 18a is heated in an evacuated sealed tube at 130°C for 1 hour 19a is obtained quantitatively. The polymer 19a is soluble in THF and the sample purified from THF-hexane is a yellow fibrous material with A/vv = 5.2 X 10 and A/n = 3.4 x 10, and readily forms amber, free-standing films by casting from toluene solution. By this ROP method, symmetrically and unsymmetrically substituted poly(ferrocenylsi-poly(ferrocenylsilanes) (19) [71,72] and polysilane-poly(ferrocenylsilane) copolymers, (20) [73] have been prepared. The ROP of [l]ferrocenophane with unsymmetrically methylated cyclopentadienyl rings (21) to investigate the C—Si bond cleavage mechanism in the thermal ROP gives a polymer (22) in which three types of silicon environment exist, showing that... 

Rulkens, R., Resendes, R., Verma, A. et al. (1997) Ring-opening copolymerization of cyclotetrasilanes and sificon-bridged [ 1 ]fenocenophanes Synthesis and properties of polysilane-poly(ferrocenylsilane) random copolymers. 

Polymerization ofiVIasked Disilenes. A novel approach, namely, the anionic polymerization of masked disilenes, has been used to synthesize a number of poly(dialkylsilanes) as well as the first dialkylamino substituted polysilanes (eq. 13) (111,112). The route is capable of providing monodisperse polymers with relatively high molecular weight M = lO" — 10 ), and holds promise of being a good method for the synthesis of alternating and block copolymers. 

In a continuing study of substituent effects on the spectra of polysilane derivatives, we have succeeded in the preparation of the first soluble poly(diarylsilane) homopolymers. Materials of this type have traditionally proved to be insoluble and intractable. Very recently, West and co-workers have reported the preparation of some soluble copolymers which contain diphenylsilylene units (48,49). 

Dendrimers, or arborols, or cascade, or cauliflower, or starburst polymers, were first synthesized in the early 1980s [3,4]. In 1985 Tomalia et al. [5] and Newkome et al. [6] presented the first papers dealing with dendrimers. A multitude of dendrimers have been presented in the literature ranging from polyami-doamine [7,8],poly(propylene imine) [9,10], aromatic polyethers [11-13] and polyesters [14, 15], aUphatic polyethers [16] and polyesters [17], polyalkane [18-19], polyphenylene [20], polysilane [21] to phosphorus [22] dendrimers. Combinations of different monomers as well as architectural modifications have also been presented. For example, chirality has been incorporated in dendrimers [23,24]. Copolymers of linear blocks with dendrimer segments (dendrons) [25-27] and block-copolymers of different dendrons have been described [28]. 

Linear polysilane polymers, properly called poly(silylene)s, can be obtained as homopolymers or copolymers. Continuation of the polysilane chain consumes two of the four valences of each silicon atom the other two are taken up by pendent groups, which may be the same (5.1) or different (5.2). Copolymers (5.3), which contain two or more kinds of silicon atoms, can be made up from units like those in 5.1 or 5.2. A typical example is the copolymer of Me2Si and PhMeSi units,... 

Semi-empirical understanding of PM-transition characteristics and main chain stiffness of rod-like polysilanes thus leads to the new idea that minute structural modification of the achiral and chiral alkyl side groups could critically modify the transition characteristics, as indeed demonstrated in a series of 16-based copolymers, poly ((S)-3,7-dimethyloctyl-3-methylbutylsilane)-co-((S)-3,7-dimethyloctyl-2-methylpropylsilane) (22) and poly ((S)-3,7-di-methyloctyl-3-methylbutylsilane)-co-((P)-3,7-dimethyloctyl-2-methylpropyl-silane) (23) (see Scheme 5). 

Comb-like graft copolymers with polysilane backbone and poly(IBVE) branches were reported by Matyjaszewski and Hrkach [61]. The IBVE monomer was grafted from triflated poly(methylphenyl silylene) at -30 °C using acetone as a... 

The use of polysilanes as photoinitiators of radical polymerization was one of the hrst means whereby they were incorporated within block copolymer structures [38 0], albeit in an uncontrolled fashion. However the resulting block copolymer structures were poorly defined and interest in them principally lay in their application as compatibilisers for polystyrene (PS) and polymethylphenylsilane blends PMPS. The earliest synthetic strategies for relatively well-defined copolymers based on polysilanes exploited the condensation of the chain ends of polysilanes prepared by Wurtz-type syntheses with those of a second prepolymer that was to constitute the other component block. Typically, a mixture of AB and ABA block copolymers in which the A block was polystyrene (PS) and the B block was polymethylphenylsilane (PMPS) was prepared by reaction of anionically active chains ends of polystyrene (e.g. polystyryl lithium) with Si-X (X=Br, Cl) chain ends of a,co-dihalo-polymethylphenylsilane an example of which is shown in Fig. 2 [43,44,45]. Similar strategies were subsequently used to prepare an AB/ABA copolymer mixture in which the A block was poly(methyl methacrylate) (PMMA) [46] and also a multi- block copolymer of PMPS and polyisoprene (PI) [47]. 

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