Comonomer donor-acceptor

In this paper, we report efforts to find donor/acceptor systems, comprised of at least one multifunctional monomer, capable of sustaining rapid free-radical polymerization without the need for external photoinitiators. Although we will include in this report comonomer systems which form ground state CT complexes, we stress that the primary mechanism for generating free-radical in each case may not be via excitation of ground state CT complexes. 

Control of the charge injection and transport by introduction of electron donor-acceptor substituents (or comonomers and end-capping groups)... 

This paper summarizes chemical grafting techniques explored in this laboratory that have potential biomedical application. These reactions, initiated by ceric ions, persulfate-bisulfite redox systems, or the presence of comonomers forming donor-acceptor complexes, were carried out in an aqueous environment under conditions which, with suitable modifications, might be tolerated in vivo. Grafting onto tissue surfaces by means of ionizing radiation will not be discussed since techniques for avoiding undesirable side reactions have not yet been developed. 

Donor-acceptor polymerization takes place on reacting rat skin with equimolar amounts of methacrylate (or isodecylacrylate), zinc chloride, and styrene even for as short a period as 20 mins. With a large excess of zinc chloride, polymer formation on collagen takes place with the maleic anhydride-styrene comonomer system. In the reactions where donor-acceptor polymerization occurred, yields were of the same order as those obtained solely with CAN initiator. 

First, from e.g. strong donor — acceptor complex between comonomers or even a betaine structure. This intermediate undergoes faster ion-coupling than the corresponding ion-molecule reaction. 

Through the hybrid incorporation and copolymerization of various conjugated units, the electronic and electrochromic properties of the resulting polymers can be varied to cover colors across the entire visible spectrum. In this manner, the advantages of different conjugated vmits (i.e., low oxidation potential or solubilizing substituents) can be utilized while playing on the interaction of the comonomers (i.e., with the donor-acceptor systems). 

Stille coupling has been used by Li et al to synthesize the donor-acceptor co-polymer P23 consisting of dithienyl-DPP and fused thienothiophene (TT) units. OFET devices fabricated from this polymer showed a high hole mobility of 0.94 cm V s due to significant intermolecular %-% donor-acceptor interactions between TT and DPP fused heterocyclic units.Additionally, a stannyl derivative of dithienothiophene has been recently co-polymerized by Shahid et al. with bis(5-bromo-2-thiophenyl)- and bis(5-bromo-2-selenophe-nyl)-DPP comonomers. Both polymers exhibited ambipolar characteristics in OFET devices. The thiophene-based co-polymer analog showed a higher... 

Network properties. The UV-cured materials obtained by crosslinking polymerization of mixed donor-acceptor monomers or by crosslinking copolymerization of multifunctional allyl monomer with an acceptor comonomer in presence of 1 wt-% of TPO (diphenyl-(2,4,6)-tri-methylbenzoyl)phoshine oxide) as photo-initiator were placed between glass lids allowing for the formation of 1 mm-thick samples after... 

Scherowsky and Beer (63 included a fluorescent dye in a FLC polymer by copoly-merization. As shown in formula 46. the fluorcacent dye consists of a donor-acceptor substituted naphthalidmide. 46b, with the bexyloxy group as donor, exhibits the same phase-transition temperatures as the bomopolymer, when containing S wt% dye comonomer. The spontaneous polarization of 46b b reduced of about 20% compared with the bomopolymer (in maximum from 15S to 115 nOcm ). The tilt angle b less than 10% (e.g., from 36 to 33 at 110 C). The response time of the fluorescent copolymer 46b b distinctly shorter, as shown in Figure 44. It reaches values below 1 ms... 

Some pairs of very strongly electron-donor and electron-acceptor monomers, such as p-methoxystyrene and dimethyl cyanofumarate, undergo spontaneous alternating copolymerizations without any added free-radical initiator, although heat may be required [Hall and Padias, 1997, 2001]. Initiation involves reaction of the comonomer pair to form a diradical,... 

---