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Polysiloxanes have been found to be the most important and commercial family of synthetic inorganic polymers. The unique structure of the siloxane bond provides them with unusual features such as a high bond angle, nearly inexistent torsional barrier and a semi-ionic character due to the difference of electronegativities between the silicon and oxygen atoms. Also, silicon-based polymers have been used for the delivery of pharmaceutical and diagnostic compounds involving the use of nanoparticles with different shapes and sizes, as well as hydrogels, including those based on silicon compounds. Hydrogels based on silicon polyolates are rather promising. Some of them exhibit pronounced anti-inflammatory, regenerating, and protective activity, readily penetrate the organism and facilitate drug penetration into the tissues. Due to these properties, polysiloxanes have encountered a big opportunity as an important material in the area of biomedical engineering; the big influence they have in the area of prosthetic dentistry, tissue engineering, cell growth, wounded skin treatments is noteworthy. For the reasons briefly described above, we consider the fact of doing a review about how the polysiloxanes have been used over the years as polymeric matrices that are used in several applications in the field of biomedical engineering.

In this research, we focus on the study of the operating conditions that influence on suspension process for obtaining (co)polymers of styrene with polar monomers (copolymers of styrene with acrylate of butyl (S-BA) and copolymers of styrene with vinyl acetate (S-VAc)) using the technique of conventional free radical polymerization (FRP). At higher agitation speed, the reaction performance decreases. Likewise, the influence of the molecular weight of the dispersing agent, in this case polyvinyl alcohol (PVA), influences the polymerization performance was also observed. That is, at a higher molecular weight of PVAs, there is an increase in the particle size of the bead and in the polymerization yield. Finally, there is an influence of the polar part on the copolymer both for the yield and for the particle size of the bead. When obtaining copolymers of S-VAc, the yield is lower compared to the respective styrene homopolymer and higher in the S-BA.

In the ambit of the synthesis of silicon polymers and elastomers, there are a lot of variables that affect the final properties of the material, and consequently, their applications. In this work, we synthetized polymethylhydrogensiloxane using the ring opening polymerization (ROP) with 2,4,6,8-tetramethylcyclotetrasiloxane as monomer (D4H), a synthetic aluminosilicate like catalytic species and hexamethyldisiloxane as chain blocker. We made a set of experiments, in order to find the effect on the reaction yield, the absence of crosslinking, crosslinking degree and the mechanical properties of the final polymers. We found that the factor “chain blocker addition time” is significant for yield reaction and crosslinking degree of the elastomers, obtaining a greater crosslinking degree and reaction yield when is added at the beginning of the reaction. Also, using DSC measurements, we found an endothermal signal in 553 K corresponding to the elastomer’s chains rearrangement to dissipate the heat supplied. We obtained PMHS chains up to 24,270 g/mol indicating the ability of this kind of catalysts to achieve relatively high molecular weight chains.

Pulsed-laser polymerization combined with polymer analysis by NMR and size-exclusion chromatography is used to study the radical copolymerization kinetics of isoprene (IP) with glycidyl methacrylate (GMA). The copolymer is characterized by a close-to-alternating microstructure, with the addition of IP leading to a significant decrease in the composition-averaged propagation rate coefficient. A rigorous fitting strategy is developed to fit a mixed penultimate model to the data, with the selectivity of the IP, but not the GMA, macroradical dependent on the penultimate unit.

Homo and copolymerization of isoprene (IP) with small amounts (1–10 wt %) of glycidyl methacrylate (GMA) are conducted using controlled-living radical polymerization (CRP) mediated by nitroxides (NMP) at 120 °C and 1170 kPa in solution with toluene (30 wt % solids). N-tert-butyl-N-(2-methyl-1-phenylpropyl)-O-(1-phenylethyl) hydroxylamine (TIPAL) is successfully used as a control agent (unimolecular process) although other controllers are also tested (TIPNO and OH-TEMPO in a bimolecular process using BPO as initiator). Chain extension experiments demonstrate the livingness of the synthesized materials. Several additives (acetic anhydride, camphorsulfonic acid and glucose) prove effective in accelerating the reactions. All the successful polymerizations result in first-order kinetics with respect to the monomer, yielding average molecular weights (Mn) of about 75% compared to the theoretical Mn (Mn, theo) with dispersities (Ð) ranging from 1.2 to 1.7 depending on the agent used for control. Controlled grafts of poly (isoprene-co-GMA) are also attached to polyisoprene via nitroxide chemistry. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45108.