Highly crosslinked core

The first elastomeric protein is elastin, this structural protein is one of the main components of the extracellular matrix, which provides stmctural integrity to the tissues and organs of the body. This highly crosslinked and therefore insoluble protein is the essential element of elastic fibers, which induce elasticity to tissue of lung, skin, and arteries. In these fibers, elastin forms the internal core, which is interspersed with microfibrils [1,2]. Not only this biopolymer but also its precursor material, tropoelastin, have inspired materials scientists for many years. The most interesting characteristic of the precursor is its ability to self-assemble under physiological conditions, thereby demonstrating a lower critical solution temperature (LCST) behavior. This specific property has led to the development of a new class of synthetic polypeptides that mimic elastin in its composition and are therefore also known as elastin-like polypeptides (ELPs). 

Hollow phosphazene microcaspules can be prepared by the reaction of poly(dichlorophosphazene) with hexamethylenediamine on the surface of a amino-silanized silica particle. Subsequent reaction of the product particles with an HF/NH4 solution that dissolves the silica from within the partcles, leaving a hollow shell. Polymer (50), which was resistant to degradation under the conditions used to remove the core, is highly crosslinked. 

Cationic polymer-based nanogels are nanosized swollen cationic hydrogel particles composed of chemically or physically crosslinked polymer net-works/ The highly hydrated properties and tightly crosslinked core makes these systems superior in colloidal stability. These properties make these nanogels suitable for encapsulation of therapeutic nucleic acids in the core for carrier systems for delivery, in comparison to macroscopic hydrogels or nanoparticles. ... 

The core-shell particles were prepared by seeded semi-continuous emulsion polymerization under monomer-starved conditions. A detailed experimental procedure for similar latices is given by Winnik et al. [20] and Kruger et al. [21]. The seed was prepared by batch emulsion polymerization. After synthesizing the PBMA core a highly crosslinked PnBA-shell with MAA comonomer... 

These polymers appear to be amorphous as they soften at 100-120 C, are resilient up to 215-240 C and are plastic above 260 C, a much different behavior from highly crystalline PPS. Lenz et al. postulated that the structure of the Macallum polymer is a crosslinked core with attached, more or less extended, linear chains. However, any linear PPS chains should be crystalline unless they are very short. 

He reported that polymers prepared in this manner generally contained more than one sulfur atom per repeat unit (x in the range 1.2-2.3). In addition the polymerization reaction was highly exothermic and difficult to control, even on a small scale.7 Certainly Macallum s work sparked an interest in polyphenylene sulfide (PPS) and triggered a series of investigations that eventually led to the commercial production of PPS. In 1954 Macallum sold his patents to Dow Chemical Co. where this polymerization scheme was studied further. However, the problems associated with the severe polymerization conditions and control of the exothermic reaction remained largely unsolved.9 Lenz and coworkers at Dow have studied the mechanism of the Macallum polymerizationlO and the structure of the polymer produced, ii The structure postulated consists of a crosslinked core to which are attached more or less extended, linear chains. 

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