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PubMed2000

Biomechanical performance of silicone and latex external condom catheters.

Standard in vivo biomechanical performance tests and a pilot clinical study of latex external condom catheters (ECCs) and silicone ECCs demonstrated the superior performance of the silicone ECC over that of the latex ECC. The silicone ECC has a self-adhesive that binds more securely to human skin than the self-adhesive of latex ECC. In addition, the moisture vapor transmission through silicone is significantly greater than through latex. The aggressive self-adhesive of the silicone ECC significantly reduced ECC catheter pop-off compared to that of latex ECC. Silicone ECC removal can be facilitated by the application of a warm, wet cloth to the exterior surface of the silicone ECC, which significantly reduces its self-adhesive force. Constant, gentle traction is then applied to the silicone catheter outlet end to achieve atraumatic silicone ECC removal. On the basis of the results of these standardized tests and pilot study, the silicone ECC is recommended for incontinent men without obstructive uropathy.

Adhesives↗
PubMedDate not supplied

[Study on the influence of silicone oils of various viscosities on anterior eye structures].

Intraocular silicone oil tamponade plays important role in the treatment of complicated retinal detachments. Aim of present study was an investigation of the effects of different silicone oil fluids on the anterior chamber structures. Standard silicone oils with 100, 990, 3690 mPa.s viscosity and highly purified silicone oil with viscosity 5000 mPa.s were used. Corneal silicone oil impregnation was observed in corneas which were in contact with silicone oil with 100 mPa.s. viscosity. Silicone oil impregnation of uveal structures was observed in all cases after the 4 months follow-up. "Posterior collagenous layer" was observed subendothelial in eyes injected with various silicone oil fluids including highly purified one. Results of our investigation show that use of highly purified silicone oil does not allow to reduce the side effects on ocular structures caused by emulsification or a barrier to the nutrition and exchange of products of metabolism provided by silicone oil bubble.

Animals↗
PubMed1994

Silicone gel filled breast implants and connective tissue disease: an overview.

OBJECTIVE: To review the literature examining the association of silicone gel filled implants and connective tissue disease. METHODS: Computerized literature searches and manual review of bibliographies. RESULTS: Numerous concerns have arisen regarding the safety of silicone gel filled breast implants. The structure of these prostheses is reviewed. Silicones are not biologically inert. Injectable as well as implantable silicones have proven capable of eliciting inflammatory and fibroproliferative responses. Silicone leakage from silicone gel filled implants is well documented as is distant migration of silicone in the host. In the past decade, over 60 cases of connective tissue disease following mammoplasty with silicone gel filled implants have been reported. About half of these patients developed scleroderma or scleroderma-like illnesses. This reported overrepresentation of scleroderma compared to other rheumatic diseases mimics the Japanese experience with injectable silicones. Possible biological rationale for the association is presented. CONCLUSION: The physical and biological properties of silicone gel filled implants and their behavior in vivo is compatible with the hypothesis that they may contribute to the development of connective tissue disease. The association seems most likely with scleroderma; however, there is as yet inadequate epidemiological data to definitively establish causality.

Animals↗
PubMedDate not supplied

Magnetic resonance study of virgin and explanted silicone breast prostheses. Can proton relaxation times be used to monitor their biostability?

The development of sensitive and non invasive magnetic resonance (MR) techniques for monitoring the fate of silicones in breast prostheses in vivo requires detailed knowledge of the MR properties of these silicones. To characterize changes in the proton dynamics, relaxation time measurements (T1 and T2) were obtained on virgin and explanted breast prostheses using both spectroscopic and imaging techniques in a magnetic field of 1.5 Tesla. Averaged transverse relaxation times (T2) were observed to depend neither on the measurement technique employed (virgin silicone, T2 = 160 +/- 5 msec with imaging and 154 +/- 9 msec spectroscopically) nor on the effect of being implanted in the body for various periods of time ranging from 4 months to 17 years (explanted silicone, T2 = 164 +/- 16 msec with imaging and 159 +/- 25 msec spectroscopically). Average longitudinal relaxation times (T1) were also found to be similar for virgin and explanted prostheses (virgin silicone T1 = 899 +/- 32 msec, explanted silicone T1 = 879 +/- 75 msec, measured with imaging), but appeared to depend on the measurement technique employed (virgin silicone T1 = 764 +/- 17 msec, explanted silicone T1 = 765 +/- 23 msec, measured spectroscopically). Although the measured relaxation times did not reveal any differences between virgin and explanted prostheses, marginal differences were detected between the relaxation times of explanted prostheses from different manufacturers. More reference data on standard silicone products may be required before changes in implanted silicone can be assessed using proton magnetic relaxation times.

Biocompatible Materials↗
PubMed1990

Silicon facilitation of copper utilization in the rat.

An eight-week, 2 x 4 factorial rat experiment using two levels of dietary copper and four levels of dietary silicon was conducted to further delineate a previously observed silicon-copper interaction in which silicon appears to mimic copper in its effect on the composition of the aorta. Dietary copper concentrations were 1.4 (deficient) and 5.4 (adequate) mg/kg diet, and silicon concentrations were 5, 135, 270, and 540 mg/kg diet. Compared with the lowest level of silicon and copper, weight gains were 15.5% higher for rats fed 540 mg silicon/kg diet and 14.3% higher for those fed 5.4 mg copper/kg diet. The growth-promoting effects of silicon and copper were additive. Evidence that silicon elevated the copper status of copper-deficient rats includes an increase in packed-cell volume by 540 mg silicon/kg diet in the otherwise packed-cell volume-depressed, copper-deficient rats, accompanied by a trend toward higher hemoglobin values and lower relative heart weights. In the copper-adequate rats, evidence that 540 mg silicon/kg diet elevated their copper status includes a two-fold increase in the blood-plasma copper concentration, a three-fold increase in ceruloplasmin activity, and an increase in cardiac, renal, and hepatic copper concentrations. In addition, 540 mg silicon/kg diet resulted in higher aortic dry mass and aortic elastin content in both copper-deficient and copper-adequate rats. While dietary silicon concentrations of 135, 270, and 540 mg/kg diet were all effective in increasing aortic elastin in the copper-adequate rats, only 540 mg silicon/kg diet increased aortic elastin in the copper-deficient rats. These data indicate that some of the metabolic effects attributed to silicon may be manifested through a silicon-facilitated increase in copper utilization.

Journal Article↗
PubMed1998

In vitro and in vivo microbial adhesion and growth on argon plasma-treated silicone rubber voice prostheses.

Patients who undergo a total laryngectomy usually receive a silicone rubber voice prosthesis for voice rehabilitation. Unfortunately, biofilm formation on the esophageal side of voice prostheses limits their lifetime to 3-4 mon on average. The effects of repeated argon plasma treatment of medical grade, hydrophobic silicone rubber on in vitro adhesion and growth of bacteria and yeasts isolated from voice prostheses, as well as in vivo biofilm formation are presented here. In vitro experiments demonstrated that initial microbial adhesion over a 4 h time span to plasma-treated, hydrophilized, silicone rubber was generally less than on original, hydrophobic silicone rubber, both in the absence and presence of a salivary conditioning film on the biomaterial. Growth studies over a time period of 14 d at 37 degrees C in a modified Robbins device, showed that fewer Candida cells adhered on plasma-treated, hydrophilized silicone rubber as compared to on original, hydrophobic silicone rubber. For the in vivo evaluation of biofilm formation on plasma-treated silicone rubber voice prostheses, seven laryngectomized patients received a partly hydrophilized "Groningen Button" voice prosthesis for a planned evaluation period of 4 wk. After removal of the voice prostheses, the border between the hydrophilized and the original, hydrophobic side of the prostheses was clearly visible. However, biofilm formation was, unexpectedly, less on the original, hydrophobic sides, although the microbial compositions of the biofilms on both sides were not significantly different. Summarizing, this study demonstrates that in vitro microbial adhesion and growth on silicone rubber can be reduced by plasma treatment, but in vivo biofilm formation on silicone rubber voice prostheses is oppositely enhanced by hydrophilizing the silicone rubber surface. Nevertheless, from the results of this study the important conclusion can be drawn that in vivo biofilm formation on voice prostheses is controlled by the hydrophobicity of the biomaterials surface used.

Journal Article↗
PubMed2005

A continuous-wave Raman silicon laser.

Achieving optical gain and/or lasing in silicon has been one of the most challenging goals in silicon-based photonics because bulk silicon is an indirect bandgap semiconductor and therefore has a very low light emission efficiency. Recently, stimulated Raman scattering has been used to demonstrate light amplification and lasing in silicon. However, because of the nonlinear optical loss associated with two-photon absorption (TPA)-induced free carrier absorption (FCA), until now lasing has been limited to pulsed operation. Here we demonstrate a continuous-wave silicon Raman laser. Specifically, we show that TPA-induced FCA in silicon can be significantly reduced by introducing a reverse-biased p-i-n diode embedded in a silicon waveguide. The laser cavity is formed by coating the facets of the silicon waveguide with multilayer dielectric films. We have demonstrated stable single mode laser output with side-mode suppression of over 55 dB and linewidth of less than 80 MHz. The lasing threshold depends on the p-i-n reverse bias voltage and the laser wavelength can be tuned by adjusting the wavelength of the pump laser. The demonstration of a continuous-wave silicon laser represents a significant milestone for silicon-based optoelectronic devices.

Journal Article↗
PubMed1998

Silicon Crystals in Water of Autoclaved Glass Bottles.

Crystals were detected in glass bottles containing autoclaved (standard cycle: 1218 C, 17 lb/in2, for 20 min) tap water. Bottles were fitted with a sipper tube and stopper. Crystals were observed twice at approximately a 6-month interval. Analysis of crystals and crystal-laden water by transmission electron microscopy and inductively coupled plasma and energy X-ray analysis revealed that the crystals were silicon. Subsequently, procedures and processes involved with preparation of water bottles were analyzed to determine the source or factors involved with silicon contamination. Analyses of silicon concentrations were performed on samples of tap water (0.88 to 1.20 ppm), tap water autoclaved in polycarbonate (0.89 to 1.20 ppm) and glass water bottles (0.84 to 11.0 ppm), glass and polycarbonate bottles after purposeful contamination of tap water with various amounts of alkaline detergent (1.10 to 1.70 ppm), and on steam condensate from the autoclave (0.23 and 0.47 ppm) to ascertain the source of silicon. Water from autoclaved glass bottles had greater concentrations of silicon, compared with unautoclaved tap water. Siliconized rubber stoppers and stainless-steel sipper tubes were excluded as sources of silicon contamination. Autoclaving glass bottles with stopper pieces did result in crystal formation, despite only modest increases in silicon concentration. Detergent contamination did not influence silicon concentrations. Analysis of the data indicated that autoclaving glass water bottles can lead to increases in silicon concentration and, under some circumstances, crystals may form.

Journal Article↗
PubMed1995

The effect of silicone-gel on the immune response.

Silicone materials have been used in medical applications for at least 30 years. Despite this long history of use the question whether silicones can mediate an immunological reaction that may be detrimental to the host remains unanswered. Most studies on the biocompatability of silicones conclude that silicones are chemically stable compounds, which however are often capable of eliciting a benign chronic inflammatory response. Recently, our laboratory has conducted a series of animal experiments aimed at determining the immunological adjuvancy potential of silicone-gel taken from commercial breast implants. Our previous studies have indicated that silicone-gel is a potent humoral (antibody) adjuvant. Our present studies have found that silicone-gel is capable of eliciting auto-antibodies to rat thyroglobulin and bovine collagen II. However this immune response did not produce any histological evidence of thyroiditis or arthritis. Theories to explain why silicone-gel behaves as an adjuvant are discussed along with discussion of the hypothesis on the desirability of replacing silicone-gel with a more hydrophilic material in bioimplants.

Adjuvants, Immunologic↗
PubMed1987

Acute and latent pneumonitis after subcutaneous injections of silicone in transsexual men.

We evaluated 13 transsexual men who were hospitalized for symptoms resulting from illicit subcutaneous injections of silicone. Patients with acute silicone pneumonitis were admitted because of fever, bilateral pulmonary infiltrates, and hypoxemia (mean PaO2, 58 +/- 14 mm Hg). Most patients in this group had received new silicone injections within hours of admission, but one presented with the same clinical syndrome a few hours after a brawl. The alveolitis of acute silicone pneumonitis was characterized by increased numbers of alveolar macrophages, neutrophils, and eosinophils (p less than 0.05 compared with those in normal persons with a similar smoking history). Evidence of alveolar hemorrhage was also present in some cases. Alveolar macrophages contained large, pleomorphic, cytoplasmic inclusions, which were identified as silicone by atomic absorption and infrared spectrometry. Patients with latent silicone pneumonitis underwent clinical study at much longer times after the silicone fluid injections because they developed local inflammatory phenomena at the sites of previous injections. Pulmonary function studies usually showed slight restrictive changes, and bronchoalveolar lavage disclosed abnormalities similar to those found in patients with acute silicone pneumonitis, although to a lesser degree. Thus, illicit silicone fluid injection carries a serious respiratory risk since it can induce pneumonitis, followed in some patients by respiratory failure.

Acute Disease↗
PubMed1980

Tissue effects of new silicone mammary-type implants in rabbits.

Two new types of silicone mammary-type implants designed to reduce silicone leakage by a gel barrier or to insulate tissue from silica in standard implants (by silicone coating) were placed in rabbits. Standard-type silicone implants were placed as controls. Capsules histologically similar to those that occur in humans occurred around many implants, although no grossly visible capsular contraction occurred. Inflammation was minimal around all types of implants, and the capsules appeared similar. Myofibroblasts were seen around implants within the first three weeks only. Scanning electron microscopy with energy-dispersive x-ray analysis was used to positively identify silicon in tissues around the implants. Silicon was found in tissues from 55% of the standard and 60% of the silicone-coated implants, while it was found in only 10% of capsules around implants containing a gel barrier layer. We conclude that both kinds of new implants incite minimal reaction in rabbits, and that a gel barrier can reduce silicone leakage from silicone implants.

Animals↗
PubMed1996

The epidemiology of scleroderma among women: assessment of risk from exposure to silicone and silica.

OBJECTIVE: To investigate the relationship between exposure to silicone (including breast implants) and silica and the development of scleroderma (systemic sclerosis, SSc) among women. METHODS: A population based case-control study was conducted among women in Michigan. 274 confirmed cases of SSc diagnosed between 1985 and 1991 were identified by contacting rheumatologists, hospitals, and a scleroderma support group. These cases and 1184 controls were interviewed by telephone to ascertain past exposures to silicone or silica. RESULTS: Silicone in the form of breast implants was not associated with significantly increased risk of SSc (adjusted odds ratio, 1.30; 95% confidence interval, 0.27 to 6.23). Among 20 other potential silicone exposure surveyed, self-reported exposure to silicone based glues, sealants, and caulks, manufacture or repair of windows or windshields, repairing or frequently using photocopy machines, consumption of simethicone-containing antacids, and implanted medication delivery pumps were significantly associated with SSc. However, blinded assessment of all job and hobby descriptions in terms of their potential for silicone exposure failed to support the first 3 associations, antacid consumption may have been confounded by esophageal dysmotility before the diagnosis of SSc, and other silicone containing device categories (pacemakers, central nervous system shunts, other shunts and catheters) were not significantly associated with SSc. Surgically implanted metallic fixation devices were associated with significantly reduced risk for SSc. No association was detected between SSc and silica dust exposure. CONCLUSION: Consistent with other studies, we found no increased risk of SSc among women with silicone breast implants, equivocal evidence of risk from other silicone exposures, and no evidence of risk from silica exposure.

Adolescent↗
PubMed1984

The biologic basis for the clinical application of the silicones. A correlate to their biocompatibility.

The polysiloxanes (silicones) are a group of inert and inorganic compounds that were introduced over two decades ago. The pure form, termed medical-grade silicone, has a wide variety of clinical applications. Almost all surgical fields have used a product made of silicone. Silicone has been found to be an inert material, with minimal reaction of the biologic system to its presence. However, multiple clinical problems still exist due to certain applications of silicone products. The problems are related to its surface properties; In the blood thrombi form around silicone implants that may dislodge and cause symptoms around the implants. Scar formation may occur, and internal wound healing problems in the breast cause spherical contracture. In the eyes, where transparencies are needed, as in the intraocular lens implant, the scar interfaces with the visual image transmissions. Some of these internal problems relate to the hydrophobic nature of the silicone surface and have been resolved in part by adsorbing a wetting agent, such as povidone, to the surface. Such obviation has gained wide clinical application in surface coating of the intraocular lens. In search of an ideal implantable material, silicone, the most applicable, is still far from being called the ideal implant. Perhaps with the changes of its surface properties, such as introducing wetting agents to its surface, a new dimension in clinical applications will open the horizons of silicone in the 1980s.

Animals↗
PubMed1997

A review of the possible health implications of silicone breast implants.

BACKGROUND: The silicone gel breast implant has long been an important method of reconstruction for the mastectomy patient. Because of concerns about possible health implications of the implant, the Food and Drug Administration banned its use for augmentation mammaplasty and limited its use in the mastectomy patient to a research protocol study. This article reviews the recent literature about the possible health hazards of the silicone implant. METHODS: In this review of the literature, specific attention was directed toward structural failure of the device as well as the diagnosis of rupture, tissue response to silicone, systemic immunologic response to silicone, the relationship of silicone to connective tissue diseases, and the association of the silicone implant with breast carcinoma in both the augmentation mammaplasty patient and the patient undergoing postmastectomy reconstruction. A total of 88 works were reviewed. RESULTS: The literature fails to support an association between silicone gel breast implants and systemic diseases. Although implants may cause local symptoms, rupture over time, or be associated with an immunologic reaction, comprehensive epidemiologic studies have concluded that there is no connection between breast implants and the known connective tissue diseases or between the implants and breast carcinoma. There is no increase in the risk of recurrence in mastectomy patients reconstructed with implants and no delay in the detection of recurrences. Recent laboratory studies in animals suggest that silicone may have anticarcinogenic effects. CONCLUSIONS: Silicone gel breast implants may rupture and cause local symptoms, but they have not been demonstrated to be a systemic health hazard for patients who have undergone augmentation mammaplasty or postmastectomy reconstruction.

Breast Implants↗
PubMed1996

Contribution of vascular catheter material to the pathogenesis of infection: depletion of complement by silicone elastomer in vitro.

We previously have shown that vascular catheters made of silicone elastomer carry a greater risk of subcutaneous infection with Staphylococcus aureus than do polyurethane (PU), polyvinylchloride (PVC), or Teflon catheters. We further have shown that there is greater inflammation surrounding silicone catheters than there is surrounding catheters made of the other materials, suggesting that silicone produces a greater chemotactic gradient than do the other materials. This study used a functional complement opsonization assay and radioimmunoassays to compare the relative abilities of silicone, polyurethane, and polyvinylchloride to activate complement. Serum incubated in silicone catheters for 24 h had less than 30% of the opsonizing ability of fresh serum while > or = 78% of the opsonizing ability remained with serum incubated in PU or PVC catheters. Measurement of C3a des Arg, C4a des Arg, C5a des Arg, and SC5b-9 demonstrated that the loss of opsonizing ability was due to 10-fold greater alternate pathway complement activation by silicone than by PU or PVC. This finding suggests that excessive complement activation by silicone may explain the greater inflammation seen around silicone catheters in vivo and also might play a role in silicone's creating a greater risk of infection.

Catheterization↗
PubMed1996

Silicone gel and octamethylcyclotetrasiloxane (D4) enhances antibody production to bovine serum albumin in mice.

The purpose of the present study was to determine whether components of silicone breast implants [silicon (polydimethylsiloxane) oil, silicone gel, and octamethylcyclotetrasiloxane (D4)] potentiate the antibody response to bovine serum albumin (BSA) in mice. Seventy A/J mice were divided into seven groups which received the following: group I--phosphate buffer solution (PBS); group II--20 centistoke (cs) silicone oil; group III--50% silicone gel homogenized in silicone oil; group IV--incomplete Freunds' adjuvant (IFA); group V--IFA mixed with an equal volume of silicone oil; group VI--D4; and group VII--IFA mixed with an equal volume of DA. Each 0.1 mL of treatment material(s) was mixed or emulsified with an equal 0.1-mL volume of 250 micrograms/mL BSA in PBS solution. Antibodies to BSA were measured using an enzyme-linked immunosorbent assay. Our study demonstrates for the first time that both D4 and the silicone gel potentiate antibody production to BSA in mice. Histopathologic evaluation of the injection sites reveals granulomas for mice injected with IFA and D4 preparations. Whether D4 or silicone gel acts as an adjuvant against self-antigens has yet to be determined.

Adjuvants, Immunologic↗
PubMed1999

Chemical characterization of silicon-substituted hydroxyapatite.

Bioceramic specimens have been prepared by incorporating a small amount of silicon (0.4 wt %) into the structure of hydroxyapatite [Ca10(PO4)6(OH)2, HA] via an aqueous precipitation reaction to produce a silicon-substituted hydroxyapatite (Si-HA). The results of chemical analysis confirmed the proposed substitution of the silicon (or silicate) ion for the phosphorus (or phosphate) ion in hydroxyapatite. The Si-HA was produced by first preparing a silicon-substituted apatite (Si-Ap) by a precipitation process. A single-phase Si-HA was obtained by heating/calcining the as-prepared Si-Ap to temperatures above 700 degrees C; no secondary phases, such as tricalcium phosphate (TCP), tetracalcium phosphate (TeCP), or calcium oxide (CaO), were observed by X-ray diffraction analysis. Although the X-ray diffraction patterns of Si-HA and stoichiometric HA appeared to be identical, refinement of the diffraction data revealed some small structural differences between the two materials. The silicon substitution in the HA lattice resulted in a small decrease in the a axis and an increase in the c axis of the unit cell. This substitution also caused a decrease in the number of hydroxyl (OH) groups in the unit cell, which was expected from the proposed substitution mechanism. The incorporation of silicon in the HA lattice resulted in an increase in the distortion of the PO4 tetrahedra, indicated by an increase in the distortion index. Analysis of the Si-HA by Fourier transform infrared (FTIR) spectroscopy indicated that although the amount of silicon incorporated into the HA lattice was small, silicon substitution appeared to affect the FTIR spectra of HA, in particular the P-O vibrational bands. The results demonstrate that phase-pure silicon-substituted hydroxyapatite may be prepared using a simple precipitation technique.

Biocompatible Materials↗
PubMed2005

Biostability and macrophage-mediated foreign body reaction of silicone-modified polyurethanes.

In this study, the effect of soft segment chemistry on the phase morphology and in vivo response of commercial-grade poly(ether urethane) (PEU), silicone-modified PEU (PEU-S), poly(carbonate urethane) (PCU), and silicone-modified PCU (PCU-S) elastomers were examined. Silicone-modified polyurethanes were developed to combine the biostability of silicone with the mechanical properties of PEUs. Results from the infrared spectroscopy confirmed the presence of silicone at the surface of the PEU-S and PCU-S films. Atomic force microscopy phase imaging indicated that the overall two-phase morphology of PEUs, necessary for its thermoplastic elastomeric properties, was not disrupted by the silicone modification. After material characterization, the in vivo foreign body response and biostability of the polyurethanes were studied using a subcutaneous cage implant protocol. The results from the cage implant study indicated that monocytes adhere, differentiate to macrophages which fuse to form foreign body giant cells on all of the polyurethanes. However, the silicone-modified surfaces promoted apoptosis of adherent macrophages at 4 days and high levels of macrophage fusion after 21 days. These results confirm that the surface of a biomaterial may influence the induction of apoptosis of adherent macrophages in vivo and are consistent with previous cell culture studies of these materials. This study validates the use of our standard cell culture protocol to predict in vivo behavior and further supports the hypothesis that interleukin-4 is the primary mediator of macrophage fusion and foreign body giant cell formation in vivo. The impact of these findings on the biostability of polyurethanes is the subject of current investigations. Attenuated total reflectance-Fourier transform infrared analysis of explanted specimens provided evidence of chain scission and crosslinking at the surface of all of the polyurethanes. The silicone modification did not fully inhibit the oxidative biodegradation of the polyether or polycarbonate soft segments; however, the rate of chain scission of PEU-S and PCU-S seemed to be slower than the control polyurethanes. To verify this finding and to quantify the rate of chain scission in order to predict long-term biostability, an in vitro environment that simulated the microenvironment at the adherent cell-material interface was used to accelerate the biodegradation of the polyurethanes. Polyurethane films were treated in vitro for up to 36 days in 20% hydrogen peroxide/0.1M cobalt chloride solution at 37 degrees Celsius. Characterization with attenuated total reflectance-Fourier transform infrared and scanning electron microscopy showed soft segment and hard segment degradation consistent with the chemical changes observed after long-term in vivo treatment. The biostability ranking of these four materials based on rate of chain scission and surface pitting was as follows: PEU < PEU-S PCU < PCU-S. The silicone modification increased the biostability of the PEU and PCU elastomers while maintaining the thermoplastic elastomeric properties.

Biocompatible Materials↗