Crosslinking using

Crosslinking using reactions of multifunctional reagents with side groups of polymers is most frequently applied to PVA, some biopolymers containing OH-groups, partly hydrolyzed PAAm, polyamines, and other polymers. These reactions are reviewed in Ref. [52],... 

Equations 22 and 23 can be solved numerically using the method described in Ref. 5. For oligomers, the probability generating functions are calculated by the appropriate sums. For random copolymers analytical expressions for and t can be written for a polymer or crosslinker using the appropriate Schulz-Zimm parameters (5) ... 

Attempts to obtain permanently hydrophilic surfaces by other types of crosslinking chemistry were not successful. The other methods investigated included forming ionic crosslinks, using cured... 

Fig. 26. Tan 3 of a crosslinking PBD (Mw = 18 000) as a function of reaction time [31]. Parameter is the frequency co. The polymer is vulcanized at the pendant vinyl units with a bifunctional silane crosslinker using a platinum compound as catalyst. The curves intersect at the gel point resulting in...

Crosslinking using diazonium compounds usually creates deeply colored products characteristic of the diazo bonds. Occasionally, the conjugated molecules may turn dark brown or even black. The diazo linkages are reversible by addition of 0.1 M sodium dithionite in 0.2 M sodium borate, pH 9.0. Upon cleavage, the color of the complex is lost. 

Figure 5.14 PDPH reacts with thiol-containing compounds through its pyridyl disulfide end to form reversible disulfide linkages. Its hydrazide end then may be subsequently conjugated with an aldehyde-containing molecule to form hydrazone bonds. Glycoproteins may be crosslinked using this approach after periodate activation to...

The crosslinker used to form the bond between the antibody and toxin must be able to survive in vivo and not be cleaved by enzymatic or reductive means before reaching the targeted cells. 

Clear unsaturated oils are vulcanised at room temperature with sulphur monochloride to give a white, friable solid which is nonstaining and suitable for use in coloured compounds. Crosslinking using sulphur monochloride produces a white factice, but care had to be taken in its use, for if not used when fresh it develops a high level of acidity which affects compound cures severely. The acidity can be removed by steaming the factice just prior to use. Modem white factices contain a small addition of alkali to counteract any developed acidity. 

The Effect of Crosslinker Concentration on the Rate of Polymerization. Ethylene glycol dimethacrylate is used most frequently as the crosslinker for HEMA formulations useful in contact lens manufacturing. To demonstrate the effect of crosslinker concentration on the curing rate, formulations derived from HEMA/Glycerine/BME at 85/15/0.17, while varying EGDMA (from 0.34 to 0.68), the peak times were about the same (3.73 and 3.61 minutes respectively). This is reasonable due to the similarity in molecular structure of the crosslinker and the monomer, and the low amount of crosslinker used. The possible presence of other crosslinker, such as the dimerization product of HEMA, is even less a factor to be considered in polymerization kinetics, due to low concentration (normally much less than 0.1 %, in-house information). 

The first resist used to fabricate solid-state devices was a negative resist based on cyclized poly(cis-1,4-isoprene) which is crosslinked using a photoactive bis-... 

The statistical theory of crosslinking used in the last section also gives the theoretical concentration of elastically-active chains, N, which in turn determines the rubbery modulus E = 3NRT (R is the gas constant and T is the absolute temperature). At 70% reaction one calculates E - 2 x 10 dyn/cm1 2 3 4 5 6 7 8 9 10, in agreement with the apparent level in Figure 1. 

Drug substance Monomer and crosslinker used to prepare the polymer Mobile phase References... 

Effects of Curing Agent Type. Epoxide-Cured Propellant. Carboxyl-terminated polybutadiene is a linear, difunctional molecule that requires the use of a polyfunctional crosslinker to achieve a gel. The crosslinkers used in most epoxide-cured propellants are summarized in Table IV and consist of Epon X-801, ERLA-0510, or Epotuf. DER-332, a high-purity diepoxide that exhibits a minimum of side reactions in the presence of the ammonium perchlorate oxidizer, can be used to provide chain extension for further modification of the mechanical properties. A typical study to adjust and optimize the crosslinker level and compensate for side reactions and achieve the best balance of uniaxial tensile properties for a CTPB propellant is shown in Table V. These results are characteristic of epoxide-cured propellants at this solids level and show the effects of curing agent type and plasticizer level on the mechanical properties of propellants. 

Monomers, (IV), which were crosslinkable using free radical polymerization with azoisobutyronitrile or with ring-opening metathesis polymerization catalyst, C12Ru(=CHC6H5)[P(C6H11)3] were prepared by Liaw et al. (4) and used in thermosets. 

Acrylic Crosslinkers. Butanediol diacrylate (IV) (BDDA) is a popular crosslinker used in the preparation of many polymers used for inks, paints, and plastics. Low-levels of impurities can adversely affect product properties. As previously discussed, K+IDS provides a powerful qualitative technique, but yields poor quantitative data when analyzing volatile chemicals. BDDA is amenable to analysis by GC, unfortunately any higher-molecular-weight adducts exceed the volatility range amenable to GC. Moreover, BDDA is not chromophoric thereby HPLC characterization is also difficult. 

Cai, K., Itoh, Y., and Khorana, H. G. (2001). Mapping of contact sites in complex formation between transducin and light-activated rhodopsin by covalent crosslinking Use of a photoactivatable reagent. Proc. Natl. Acad. Sci. USA 98, 4877-4882. 

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