Groups, crosslinking

The ability of Ca2+ to crosslink groups and so stabilize proteins against thermal denaturation or hydrolytic attack is well illustrated by thermolysin, which involves four Ca2+ and a catalytic Zn2+. The function of the calcium is to stabilize the protein structure.404 Calcium also protects surface protein of the neural retina from tryptic cleavage.405... 

A chemical crosslinking also seems possible in the acrylonitrile polymerization by a copolymerization activity of the nitrile group (20). In fact, we found a certain extent of acid hydrolysis in acrylonitrile-styrene popcorn copolymers, which could be an indication for crosslinking groups such as ... 

Since we are considering the simplest case where each unit has one cross-linkable moiety, ws is also a fraction of the crosslinkable groups in the 5-meric chains. 

Since the crosslinking density a is the probability of any unit to be cross-linked, the number of additional crosslinked units on an, v-mcric chain, crosslinked to the first chain, is expected to be equal to a. multiplied by the number of remaining crosslinkable groups (.v— 1). Thus, the expected number of additional chains crosslinked to the. v-meric chain, which is crosslinked to the first randomly chosen chain, is a(s— 1). Averaging over all chain sizes will give the average expectance of additional chains v. 

Title Process for Preparing Poly(Arylene Ethers) with Pendant Crosslinkable Groups... 

Another innovation in in-situ microencapsulation is aminoplast shellwalls containing base-cleavable ester moiety [15]. Polyols reacted with diacids that contain thiol or hydroxy functionality produce crosslinking groups. These crosslinking groups along with urea-formaldehyde prepolymer are dissolved into the pesticide and the in-situ microencapsulation process is completed. The resultant microcapsules may contain an insecticide that is safer to handle under acidic conditions yet will rapidly release the insecticide in the alkaline gut of an insect. Alternately, base could be added to the spray tank to rapidly release capsule contents prior to application. 

Silicon centers with two or three crosslinked groups were successfully resolved in our experiments, but a silicon with only one crosslink is difficult to resolve finm a silicon that has not undergone hydrolysis. Additionally, silicon atoms substituted with SiO—H and SiO-C bonds resonate at very similar frequencies, so it is not possible to directly examine the extent of hydrolysis itself. One can at best calculate the extent of hydrolysis of the alkoxy groups by examining the extent of crosslinking. 

One possible version of the LCT concept involves the design and preparation of new monomers consisting of a rigid rodlike central unit, a characteristic of conventional liquid crystals, capped at both ends with well known crosslinking groups. The crosslinking groups were chosen from the common functionalities used for thermoset materials such as epoxy, maleimide, acetylene, etc. This... 

Table I. Interlayer Distances Found for Crosslinking Groups.

A much longer and more efficient tricyanofuran-based NLO chromophore has also been introduced into the NLO dendrimers 21 (Scheme 13), 22, and 23 (Scheme 14) in which the crosslinkable groups were functionalized at either the acceptor side or at the donor-end positions. It provides great potential not only to further enhance the macroscopic E-O activity but also to achieve the combination of desirable properties. 

Secondly, however, the carbon nanotube may be covalently functionalized with monomer units, initiator molecules or crosslinking groups, which leads to a significantly better interaction with the matrix. 

To improve their mechanical properties, chemically crosslinkable groups, including trimethoxysilane (Ho et al, 2006), cysteamine (Robb et al, 2007), acrylate (Cheng et al, 2007) and dimethylmaleimido (Harmon et al, 2003 Ruckling et al, 2002), can be introduced to the PNIPAAm chain by copolymerizing NIPAAm with functionalized monomers. After copolymerization, these crosslinkable groups exist on the polymer chains as functional groups. 

---