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A method for limiting the transmission of light through a material is disclosed. In the method, a layer composed of a hyperbranched polymer formed via a copolycyclotrimerization reaction is interposed between a light source and the material. Also provided is a method for emitting light comprising exciting the hyperbranched polymer. In addition, methods for limiting the transmission of light and for emitting light using hyperbranched polymers formed by homopolycyclotrimerization reactions are disclosed. A new class of hyperbranched polymers produced by copolycyclotrimerization is also disclosed.

A series of hyperbranched poly(ferrocenylene)s containing elements (E) of groups 14 [E = Si (hb-1), Ge (hb-2)] and 15 [E = P (hb-3), Sb (hb-4)] are prepared in good isolation yields (up to 82 wt\%) by the salt-eliminative polycoupling of dilithioferrocene with tri-(REC1(3)) or tetrachlorides of the elements (ECl4). While the polymers with no or small R groups are insoluble or partially soluble, those with long alkyl chains (R = CnH2n+1 with n >= 8) are completely soluble and film forming, The polymers exhibit solution properties characteristic of hyperbranched macromolecules: e.g. hb-1(18) shows a low intrinsic viscosity ([eta] = 0.02 dL/g) despite its high absolute molecular weight (M-w = 5 x 10(5)). Spectroscopic analyses reveal that the polymers possess rigid skeleton structures with extended conjugations, with their absorption spectra tailing into the infrared region (> 700 nm). The polymers show good thermal stability with T-d up to similar to 400 degrees C and can be graphitized into iron-containing ceramics when pyrolyzed at high temperatures, with char yields up to similar to 60 wt\%. While calcinations of the Si-containing polymers (hb-1) at 1000 degrees C under nitrogen give ceramics containing mostly alpha-Fe nanoparticles, those of Ge-(hb-2) and Sb-containing polymers (04) are completely transformed into their iron-alloys. The ceramics from the P-containing polymers (hb-3) show diffraction patterns of iron phosphides. Iron silicide nanocrystals of "large" sizes are obtained when the pyrolysis of hb-1 is conducted at a high temperature of 1200 degrees C under argon. This ceramic is highly magnetizable (M-s up to similar to 51 emu/g) and shows near-zero remanence and coercivity; in other words, it is an outstanding soft ferromagnet with a high magnetic susceptibility and practically nil hysteresis loss.

Organometallic polymers consisting of three-dimensionally alternating ferrocene and silyne units are synthesized in high yields by a one-pot procedure of coupling reactions. The hyperbranched polymers are electronically conjugated, with their absorption spectra extending into the infrared region. The polymers ceramize when pyrolyzed, with higher temperatures favoring the formation of ceramics with larger metallic nanoclusters. The ceramics containing iron silicide nanocrystals exhibit outstanding soft ferromagnetisms with excellent magnetic susceptibilities and practically nil hysteresis losses.

At present time techniques in preparing advanced ceramic materials with high electrical conductivity and magnetic susceptibility are rare. This new invention relates to hyperbranched organometallic polymers, which are useful as precursors to certain ceramic materials, processes for the preparation of such polymers and the preparation of ceramic materials from such polymers, ceramic materials and their use as ferromagnetic materials and electrically conductive materials. This Hyperbranched organometallic polymers are synthesized through the polymerization of dilithioferrocene and trichloroalkylsilanes. Pyrolysis of the hyperbranched polymers yields mesoporous, conductive, and magnetic ceramics. The three-dimensional structure of the hyperbranched polymers serves as shielding nets to keep the atom inside thereby enabling the high-yield production of the ceramic materials. Most of the hyperbranched polymer presursors of the invention are soluable in common solvents, melt at relatively low temperatures and can be processed into robust engineering forms such as thin films, which is different from the crosslinking polymer presursors as they are inherent intractable. The high iron content and the nanodimension of the iron clusters endow the ceramics with high electrical conductivity and superparamagnetic susceptibility. The saturation magnetizability of the ceramics is much higher than that from the linear polymers and the hysteresis loss is virtually zero, which means the ceramics are excellent soft ferromagnetic materials.

A simple process for fast fabrication of thin films with biomimetic morphological structures from a group of linear homopolymers is developed. Natural evaporation of tetrahydrofuran, chloroform, and hexane-dichloromethane solutions of poly(phenylacetylene)s that contain amino acid and ethylene glycol moieties under ambient conditions instantly produces three-dimensional porous films with structural patterns reminiscent of honeycombs and radiolarian shells. Morphological analysis by optical and electronic microscopy suggests that vesicles of the amphiphilic polymers serve as building blocks in the self-organization to the biomimetic structures.

While polymerizations of 1-phenyl-1-propyne (PP) and 1-phenyl-1-butyne (PB) initiated by WCl6-Ph4Sn at room temperature yield small amounts of polymers (0.05-5.3%) with low molecular weights (M(n) 8000-15000) and high polydispersity indexes (PDI up to 109), addition of C60 into the initiator mixture dramatically boosts its catalytic activity, producing polymers with high M(n)s (up to 171 000) and low PDIs (down to 2.2) in high yields (up to 99.5%). The resultant polymers are soluble, stable, and film-forming. GPC, IR, NMR, UV, and XRD analyses reveal that the polymers consist of polyacetylene chains and covalently bound C60 cages (up to 9.1 wt %). Whereas photoluminescence of C60-containing polyPPs is faint, C60-containing polyPBs emit strong blue light (λ(max) = 456 nm) readily observable with the naked eye under normal laboratory lighting. Compared with the parent C60, both two groups of the fullerene polyacetylenes show better optical limiting performance, and their THF solutions, with higher linear transmittance, attenuate the power of intense 532 nm optical pulses to lower saturation fluence.

photoconduction under visible light illumination is investigated using xerographic discharge technique in the photoreceptors of the following substituted polyacetylenes: -[HC=C(C6H5-p-R)](n)-, -[HC=C(3-C4H2S-beta -R')](n)-, and -{HC=C[(CH2)(m)-R'']}(n)-, where p = CH3 (2), CO2(CH3)(3) (4), Br (5); and R'' = CO2(CH2)(6)OCO-Biph-OC9H19 (m = 2; 6), 9-carbazolyl (m =3; 7), OCO-Biph-OC9H15 (m = 9; 8), In the undoped state, 2-4 and 6-8 show much higher photosensitivity than poly(phenylacetylene)(R = H; 1). The polyacetylenes with electron-donating and/or hole-transporting substituents perform better than do those with electron-accepting ones. The liquid crystalline polyacetylene 6 exhibits very high photosensitivity, probably because of the crystalline aggregates of its mesogenic pendants. C-60 acts as a photoconductivity enhancer when doped to amorphous 3 but functions as a quencher when mixed with liquid crystalline 6. While 3 shows low photosensitivity in the undoped state, doping with I-2 and sensitization with crystal violet dramatically increase its photosensitivity up to 41.2 x 10(-3) lx(-1) sec(-1). Copyright (C) 2000 Society of Chemical Industry.

Two short chains of C2H4On hydrocarbons terminated with Cl atom were introduced into phenylacetylene and their polymerizations were described using organorhodium complexes as catalysts. The self-assembly of the polymers was analyzed as well as their application for controlling carbazole crystal growth. Phenylacetylene with pendant groups was successfully polymerized in high yields with high molecular weight by organorhodium catalysts. The polymers showed better thermal stability than the parent polyphenyl acetates.

Pyrolysis of hyperbranched poly[1,1'-ferrocenylene(methyl)silyne] (5) yields mesoporous, conductive, and magnetic ceramics (6). Sintering at high temperatures (1000-1200 degrees C) under nitrogen and argon converts 5 to 6N and 6A, respectively, in similar to 48-62\% yields. The ceramization yields of 5 are higher than that (similar to 36\%) of its linear counterpart poly[1,1'-ferrocenylene(dimethyl)silylene] (1), revealing that the hyperbranched polymer is superior to the linear one as a ceramic precursor. The ceramic products 6 are characterized by SEM, XPS, EDX, XRD, and SQUID. It is found that the ceramics are electrically conductive and possess a mesoporous architecture constructed of tortuously interconnected nanoclusters. The iron contents of 6 estimated by EDX are 36-43\%, much higher than that (11\%) of the ceramic 2 prepared from the linear precursor 1. The nanocrystals in 6N are mainly alpha-Fe2O3 whereas those in 6A are mainly Fe3Si. When magnetized by an external field at room temperature, 6A exhibits a high-saturation magnetization (M-s similar to 49 emu/g) and near-zero remanence and coercivity; that is, 6A is an excellent soft ferromagnetic material with an extremely low hysteresis loss.

Most of the existing metal carbonyl catalysts for acetylene polymerizations need to be preactivated by chlorine-containing additives or by UV irradiation in halogenated solvents. In this work, we developed a series of "simple" metal carbonyl catalysts of general structure M(CO)(x)L-y (M = Mo, W), none of which require additives or pre-photoirradiation, most of which are air- and moisture-stable, and some of which work well in nonhalogenated solvents. The acetonitrile complexes M(CO)(3)(NCCH3)(3) initiated polymerizations of a variety of mono- and disubstituted acetylenes at room temperature. The arene and diene complexes W(CO)(3)(mes) and Mo(CO)(3)(nbd) (mes = mesitylene, nbd = 2,5-norbornadiene) are tolerant of polar groups and effected polymerizations of functional acetylenes containing ester, ether, and cyano groups. The halogenated complexes MI2(CO)(3)(NCCH3)(2) catalyzed polymerizations of phenylacetylene in toluene. The chlorine-containing acetylene monomers ClC drop CC6H5 and ClC drop CC6H13 were readily polymerized by the Mo complexes in nonhalogenated solvents such as toluene and dioxane, giving polymers with high molecular weights (M-w up to 883 x 10(3)) in high yields (up to 100\%).

Two optically active poly(phenylacetylene) derivatives bearing D-glucose and D-galactose appendages are synthesized by Rh complexes. The two polymers are chiral, showing high [α]D20 and molar ellipticity (more than 104) in the π→π* region in the CD spectra. Solvent dependence of [α]D20 and molar ellipticity further suggest that a chiral helical conformation is adopted by the two polymers.

A group of optically active polymenthoxyalkynes is synthesized. Their thermal and chiroptical properties are investigated to gain information on the structure-property relationship of the chiral polymers. The polymerization of the functional menthoxyalkynes using WCl6-Ph4Sn as catalyst and 1,4-dioxane as solvent are fulfilled in high yields and polymers have relatively low PDI. The polymers and monomers exhibit strong Cotton effects but the former have higher molar ellipticity value. The polymenthoxyalkynes with a biphenyl moiety in the side chain intervening between the backbone and the chiral center has an induced circular dichroism arising from the twisted or helix structure of the backbone.

Polyacetylene is a prototypical conducting polymer and substituted polyacetylene have also attracted much interest. Introduction of pendant groups to the polyacetylene backbone has led to discoveries of new phenomena and to the development of new materials possessing unique properties. A group of chiral menthoxyalkynes is synthesized. Polymerizations of the acetylene monomers produced optically active polymenthoxyalkynes.

Hyperbranched polyphenylenes were synthesized using a new methodology. Polymers of terminal diynes underwent postpolymerization in the solid state. Since the as-prepared polymer at low temperature was soluble, the crosslinking reaction in the film state made the polymer a promising candidate for coating materials. The nature of the catalysts played a key role in determining the molecular structures of the polymers.